critical thinking and some theories about the brain side dominance

Lesson 1.5: The Brain Dominance Theory

The next learning theory reviewed in this series is somewhat controversial. It is called the “Brain Dominance Theory,” or, technically, Lateralization of Brain Function . This theory suggests that certain approaches to thinking and learning differ according to the hemispheres, left and right, of the brain. Critics of this theory claim it is the result of pop psychology more than sound science. Indeed, common sense indicates that, of course, we utilize all parts of the brain continually–which is why I like the multi-colored graphic of the brain. It infers a kind of brain symmetry–if not of function, of form.

To utilize your own “both/and” brain power, first read the article linked above, annotating for, or taking notes on, information you want to remember and include, perhaps, in your mid-term portfolio project and for your responses to the exercises below.

UNIT 1, EXERCISE 5.1

Based on the information gleaned in the article and in # 1, design two 8 1/2 by 11 inches posters, one for each side of the brain, illustrating the same information as is on the chart, but according to how you think each kind of thinker/learner might design them. For example, the poster for “right brain” thinking/learning might be much more colorful. The student might also think of some sort of paper structure (origami?) by which to illustrate the differences. Enjoy.

UNIT 1, EXERCISE 5.2

Based on the information in the article and the chart, above, compare how friends, “R.B.” (Right Brain) and “L.B.” (Left Brain) would respond to planning a weekend getaway to the fictitious “Wilderness Resort” located in the lush, Pacific Northwest of the U.S. Activities could include: planning, packing, traveling to and from, meals, indoor/outdoor activities, and so on. Contrast R.B. and L.B. regarding at least 5 different activities. EXAMPLE : regarding packing for activities both indoor (heated pool, fully equipped exercise room, a few casino type gaming tables, dancing, etc.) and outdoor (hiking, boating, guided field trips through an old growth forest, etc.), RB takes a casual approach: whatever is clean and easy to pack. LB first checks weather forecasts and maybe the location of any poison ivy that might be growing in the forest.

An organization chart might help with this exercise:

ACTIVITY R.B. RESPONSE L.B. RESPONSE

UNIT 1, EXERCISE 5.3

1. Answer the following question (no more than about 150 words):

Though it is controversial, how do you think knowing about the Brain Dominance Theory can still help you in the learning process? As you are thinking about this subject, consider how you might enhance your current response to learning and completing assignments or tasks by trying out either new left-brain or right-brain approaches.

Left Brain vs. Right Brain: Hemisphere Function

Eagle Gamma

Freelance Writer

Eagle Gamma writes about science & technology for the BBC, the US Department of Energy, and popular magazines.

Learn about our Editorial Process

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Left and right human brain concept. Logic and creative hemispheres infographics with brain and icons of science, sense of time, language, creative, art, intuition, imagination, vector illustration

Hemispheric lateralization is the idea that both brain hemispheres are functionally different and that specific mental processes and behaviors are mainly controlled by one hemisphere rather than the other.

Left hemisphere function

The left hemisphere controls the right-hand side of the body and receives information from the right visual field, controlling speech, language, and recognition of words, letters, and numbers.

Right hemisphere function

The right hemisphere controls the left-hand side of the body and receives information from the left visual field, controlling creativity, context, and recognition of faces, places, and objects.

According to the left-brain, right-brain dominance theory, the left side of the brain is considered to be adept at tasks that are considered logical, rational, and calculating.

By contrast, the right side of the brain is best at artistic, creative, and spontaneous tasks (Corballis, 2014; Joseph, 1988).

Brain Lateralization

Brain lateralization has become a somewhat controversial topic. While evidence supports some mental capacity occurring predominantly on one side of the brain or the other, science has overturned several earlier notions relating to this topic.

Psychologists now consider functions like language, spatial processing, and certain broader tasks to have lateralization. Language uses several brain modules, many of which are situated on the left side of the brain (Taylor, 1990).

In fact, language represents one of the main areas of interest for brain lateralization and the function for which this neurological division was first found. Even the language neurons, however, may also be split among both halves of the brain (Riès et al., 2016), or located on the right side, which is more common in left-handed people (Beaumont, 2008).

The left side of the brain often contains language-processing regions such as Broca’s Area , which produces understandable sentences, as well as Wernicke’s area , which understands speech (Griggs, 2010).

Injuries to these areas result in speech pathologies, such as an inability to speak or usually listen (Broca, 1865; Pinel & Barnes, 2017). Other language functions, like associating emotions with phrases, occur on the right side of the brain (Kandel et al., 2012).

As such, language can be seen as bridging together both halves of the brain, but with some specific functionality located on one side or the other (Riès et al., 2016). Scientists have studied language, memory, and other topics through various methods, such as the “Wada test.”

This involves disabling one side of the brain chemically, then observing how the other side operates. Logical thinking, like language, often resides primarily on the left side of the brain (Dehaene, 1999).

Again, this applies more often to right-handed people, with the reverse holding true for many left-handed people. The right brain, by contrast, has more active involvement than the left in visual or spatial processing.

As such, this works while drawing, navigating around a room, or in other comparable situations. People who have right brain injuries may become clumsy or artistically inept (McGilchrist, 2019). The right brain also becomes active while recognizing faces.

As with other functionalities, there is some degree of symmetry. The left brain can also do facial recognition, but it is more perfunctory than the right brain’s work. The right brain deals with other social perception, too, like body posture (Lane & Nadel, 2002).

Another feature of the right brain is to focus one’s attention. When a person thinks about one topic, this lights up regions on the right side of the brain. Numerous other mental activities operate differently on each side of the brain.

For example, the left brain is more associated with positive emotions, while the right brain is more associated with negative emotions (Lane & Nadel, 2002). People with depression often suffer from a disproportionate ratio of right-to-left brain activity (Atchley et al., 2003; Hecht, 2010).

Comparing the left versus right sides of the brain, the left brain processes new information into an understanding of events (making it the “interpreter”), while the right brain accounts for social behaviors.

For example, the left brain may assess which actions would lead to eating food, while the right brain may nix some of these actions on the basis of social norms (one doesn’t just run through a crowd at a party to grab food).

The left brain can be seen as an analyst, breaking apart concepts into smaller, manageable chunks. By contrast, the right brain can be seen as a synthesist, developing a more cohesive view (McGilchrist, 2019).

Interestingly, the lateralization of the brain has deeper roots in the peripheral nervous systems (Craig 2005). Nerves throughout the body feed into and out of the brain.

The left brain largely receives connections from the parasympathetic system, while the right brain largely receives connections from the sympathetic system (Conesa 1995).

Together, the two halves of the brain work with the rest of the nervous system to maintain a homeostatic balance.

The two sides of the brain are connected together by several components called “commissural nerve tracts”, largely the corpus callosum.

This segment bridges the left and right brains, sharing information. In rare cases, people are born without the corpus callosum or have it surgically removed to reduce epileptic seizures.

These cases have revealed interesting information about the two halves of the brain. In people without a corpus callosum, the brain can reorganize to perform functions normally occurring on one side instead of the other.

This may even result in the person developing the use of brain regions on both sides for the same task, allowing, for example, a person to read two texts simultaneously, one on each side of the brain.

The brain can also reorganize itself under other conditions (Gómez-Robles et al., 2013). Often this involves using either a nearby region or a mirror opposite region to replace lost function. This shows how the brain structure has largely symmetrical functionality on the left versus right halves.

There are, however, some slight differences. The body is connected to the brain, so senses as well as control usually take place on the opposite side. The left brain senses and controls the right hand, the right foot, the right half of the visual field, the right ear, and so forth.

Scientists discovered this by electrically probing the brain and observing the body’s responses, which produced a map of the body’s associations in the brain.

The motor cortex produces motions for the opposite side. In right-handed people, the left motor cortex is usually larger than the right motor cortex. Left-handed people, by contrast, often have right-brain dominance.

In addition, some people are ambidextrous (able to use both sides effectively) or have mixed dominance (using the left side for some activities but the right side for others).

The brain evolved to have some asymmetry (Vallortigara & Rogers, 2005), which occurs at multiple levels, from the basic cell arrangements differing on each side to the right hemisphere sitting slightly forward of the left hemisphere (called Yakovlevian torque).

Numerous specific brain regions, like the parietal operculum or the central sulcus, have left-right asymmetry. People who have less brain asymmetry may suffer from less effective thought processes, even schizophrenia or mood disorders (Sun et al., 2015; Ribolsi et al., 2014).

Numerous other disorders also have bases in left-right brain problems (Royer et al., 2015). In one contentious theory, called bicameralism, the left-right human brain evolved only over the last three thousand years or so from having two different identities within it.

One of these minds would speak, issuing commands, while the other mind would listen, obeying. Split-brain patients often act as though they have two minds, which some neuroscientists argue may be the case (called “dual consciousness”).

For example, one side of the body may work to prevent the other side of the body from acting. This would put a more literal spin on the phrase “being of two minds.”

Roger W. Sperry, a twentieth-century neuroscientist, made numerous contributions to the understanding of the twin halves of the brain.

Sperry (1967) conducted investigations on split-brain patients, people whose left and right brains lack the normal connections between them. These people sometimes exhibit brain-side dominance, but they also display a range of distinctive behaviors from only one side or the other.

Sperry also studied animal subjects, rewiring their nervous systems to send signals to the opposite side of the body. This showed how some mental features have hard wiring on one side of the brain while other mental features can adapt to function correctly on either side of the brain.

Sperry’s work revealed that the left side of the brain contains critical modules for producing sentences but that the right side of the brain retains some language capacities, such as understanding the social context of speech. The psychology of left brain versus right brain dominance indicates that humans have brains with overlapping yet distinct halves.

Critical Evaluation

How lateralized are brain functions? Not nearly as much as people often think. While one’s brain lateralization can affect personality, this only has a small part in the overall development of an individual.

People generally use both sides of the brain equally. There are, however, numerous specific brain regions on either the left or right side, which can have powerful effects.

For example, a person who had part of the right prefrontal lobe removed became incapable of valuing long-term rewards over short-term considerations, while people with regions of the left brain removed exhibit different symptoms (Lane & Nadel, 2002).

The two sides of the brain have somewhat different contributions in many ways: how one thinks, how one perceives other people and the environment, how one feels (both consciously and unconsciously), how mentally healthy one is, and countless other facets of personality and behavior.

Left-handed people have right brain dominance for body control, which may also result in the more artistic personality for which such people are known. However, as can be seen by the fact that there are numerous right-handed artists as well as left-handed rational thinkers, brain lateralization only goes so far.

The notion of left-brain versus right-brain dominance has some basis, but it represents a false dichotomy. The complexity of the brain involves features on both sides working together, often communicating with each other through the center (Beaumont, 2008).

Many mental functions require both sides of the brain to work in unison, undermining the claim that either side outdoes the other. As a whole, the brain remains poorly understood, with scientists continuing to investigate (Halpern, 2005).

What we do know about left-brain versus right-brain dominance is that it seems to have specific patterns, such as language or logic often occurring in the left brain or emotion and social cognition often occurring in the right brain.

However, these sides can be reversed in individuals or more balanced between both sides. Also, all of these functionalities have at least some equivalent on the opposite side of the brain.

The brain has plasticity, and in cases such as injury, it will recruit other regions which can easily be located on the opposite side (Pulsifer, 2004).

However, each brain is unique. Some have different lateralization than others, and the location of functions can even develop during the course of one’s life.

What does the right side of the brain control?

The right side of the brain primarily controls spatial abilities, face recognition, visual imagery, music awareness, and artistic skills. It’s also linked to creativity, imagination, and intuition.

However, the concept of each brain hemisphere controlling distinct functions is an oversimplification; both hemispheres work together for most tasks.

What does the left side of the brain control?

The left side of the brain mainly controls logic-related tasks, such as science and mathematics, language processing, like grammar and vocabulary, and fact-based thinking. It’s also involved in analytical abilities and sequential processing.

Nevertheless, the notion of each brain hemisphere controlling distinct tasks is a simplification; in reality, both hemispheres collaborate for most activities.

Atchley, R. A., Ilardi, S. S., & Enloe, A. (2003). Hemispheric asymmetry in the processing of emotional content in word meanings: The effect of current and past depression. Brain and Language, 84 (1), 105–119.

Beaumont, G. J. (2008). Introduction to Neuropsychology (2nd ed.). The Guilford Press.

Broca, P. (1865). Sur le siège de la faculté du langage articulé. Bulletins de La Société d’anthropologie de Paris, 6 (1), 377–393.

Conesa, J. (1995). Electrodermal Palmar Asymmetry and Nostril Dominance. Perceptual and Motor Skills, 80 (1), 211–216.

Corballis, M. C. (2014). Left brain, right brain: facts and fantasies . PLoS Biol, 12 (1), e1001767.

Craig, A. D. B. (2005). Forebrain emotional asymmetry: a neuroanatomical basis? Trends in Cognitive Sciences, 9 (12), 566–571.

Dehaene, S. (1999). Sources of Mathematical Thinking: Behavioral and Brain-Imaging Evidence. Science, 284 (5416), 970–974.

Drew, W. (2020). Psychology . John Wiley & Sons.

Gómez-Robles, A., Hopkins, W. D., & Sherwood, C. C. (2013). Increased morphological asymmetry, evolvability and plasticity in human brain evolution. Proceedings of the Royal Society B: Biological Sciences, 280 (1761), 20130575.

Griggs, R. A. (2010). Psychology: A Concise Introduction (Third ed.). Worth Publishers.

Halpern, M. E. (2005). Lateralization of the Vertebrate Brain: Taking the Side of Model Systems. Journal of Neuroscience, 25 (45), 10351–10357.

Harenski, C. L., & Hamann, S. (2006). Neural correlates of regulating negative emotions related to moral violations. NeuroImage, 30 (1), 313–324.

Hecht, D. (2010). Depression and the hyperactive right-hemisphere. Neuroscience Research, 68 (2), 77–87.

Hines, T. (1987). Left Brain/Right Brain Mythology and Implications for Management and Training. The Academy of Management Review, 12 (4), 600.

Joseph, R. (1988). The right cerebral hemisphere: Emotion, music, visual‐spatial skills, body‐image, dreams, and awareness . Journal of Clinical Psychology, 44 (5), 630-673.

Kandel, E. R., Schwartz, J. H., Jessell, T. M., Siegelbaum, S. A., & Hudspeth, A. J. (2012). Principles of Neural Science, Fifth Edition (Principles of Neural Science (Kandel)) (5th ed.). McGraw-Hill Education / Medical.

Lane, R. D., & Nadel, L. (2002). Cognitive Neuroscience of Emotion (Series in Affective Science). Oxford University Press.

McGilchrist, I. (2019). The Master and His Emissary: The Divided Brain and the Making of the Western World (Second Edition, New Expanded ed.). Yale University Press.

Pinel, J. P. J., & Barnes, S. (2017). Biopsychology (10th Edition) (10th ed.). Pearson.

Pulsifer, M. B., Brandt, J., Salorio, C. F., Vining, E. P. G., Carson, B. S., & Freeman, J. M. (2004). The Cognitive Outcome of Hemispherectomy in 71 Children. Epilepsia, 45 (3), 243–254.

Ribolsi, M., Daskalakis, Z. J., Siracusano, A., & Koch, G. (2014). Abnormal Asymmetry of Brain Connectivity in Schizophrenia. Frontiers in Human Neuroscience, 8 , 1010.

Riès, S. K., Dronkers, N. F., & Knight, R. T. (2016). Choosing words: left hemisphere, right hemisphere, or both? Perspective on the lateralization of word retrieval. Annals of the New York Academy of Sciences, 13 69(1), 111–131.

Royer, C., Delcroix, N., Leroux, E., Alary, M., Razafimandimby, A., Brazo, P., Delamillieure, P., & Dollfus, S. (2015). Functional and structural brain asymmetries in patients with schizophrenia and bipolar disorders. Schizophrenia Research, 161 (2–3), 210–214.

Sun, Y., Chen, Y., Collinson, S. L., Bezerianos, A., & Sim, K. (2015). Reduced Hemispheric Asymmetry of Brain Anatomical Networks Is Linked to Schizophrenia: A Connectome Study. Cerebral Cortex , bhv255.

Taylor, I. (1990). Psycholinguistics: Learning and Using Language (1st ed.). Pearson.

Toga, A. W., & Thompson, P. M. (2003). Mapping brain asymmetry. Nature Reviews Neuroscience, 4 (1), 37–48.

Vallortigara, G., & Rogers, L. (2005). Survival with an asymmetrical brain: advantages and disadvantages of cerebral lateralization. Behavioral and Brain Sciences, 28 (4), 575–589.

Left Brain vs Right Brain Dominance

Are creative people right-brained and analytical thinkers left-brained?

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

critical thinking and some theories about the brain side dominance

Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.

Brain Health Tips

Have you ever heard people say that they are more of a left-brained vs. a right-brained thinker? From books to TV shows, you've probably heard the phrase mentioned numerous times. Or perhaps you've even taken an online test to determine whether you are right-brained or left-brained.

Given the popularity of the idea of "left-brained" and "right-brained" thinkers, it might surprise you to learn that this idea is just one of many myths about the brain.

Like most things in life, it's not all or nothing, or this OR that. We have to remember that regardless of which side of the brain is more dominant for us, both sides are involved.

Michela Buttignol for Verywell Mind

Left Brain vs Right Brain Traits

People described as left-brain thinkers are told they have strong math and logic skills. On the other hand, those who are described as right-brain thinkers are told that their talents are more on the creative side of things. Here are a few traits of each.

Traits of a Left-Brained Person

The left side of the brain is adept at certain tasks. Characteristics of the left brain include those related to:

Critical thinking

What are "left-brained" people like? They are described as logical, analytical, and orderly. The theory suggests that people who are left-brain dominant do well in careers that involve linear thinking, math, and verbal information. This includes careers such as accountant, scientist, or computer programmer.

Traits of a Right-Brained Person

According to the left-brain, right-brain dominance theory, the right side of the brain is best at expressive and creative tasks. There are several abilities popularly associated with the right side of the brain. Based on these, a right-brained thinker is good at:

Recognizing faces
Expressing emotions
Creating music
Reading emotions
Appreciating color
Using imagination
Being intuitive
Being creative

So what are so-called "right-brained people" like? They are often described as being more emotional, intuitive, and creative. They are often described as doing well in careers that involve creative expression and free-thinking, such as becoming an artist, psychologist, or writer.

Theory of Left Brain vs Right Brain Dominance

According to the theory of left brain or right brain dominance, each side of the brain controls different types of thinking. Additionally, people are said to prefer one type of thinking over the other.

For example, a person who is "left-brained" is often said to be more logical, analytical, and objective. A person who is "right-brained" is said to be more intuitive, thoughtful, and subjective.

In psychology , the theory is based on the lateralization of brain function. The brain contains two hemispheres that each perform a number of roles. The two sides of the brain communicate with one another via the corpus callosum.

The left hemisphere controls the muscles on the right side of the body, while the right hemisphere controls those on the left. This is why damage to the left side of the brain, for example, might have an effect on the right side of the body.

Click Play to Learn About the Left Brain and the Right Brain

This video has been medically reviewed by Steven Gans, MD .

History of Left Brain vs. Right Brain Theory

So does one side of the brain control specific functions? Are people either left-brained or right-brained? Like many popular psychology myths, this one grew out of observations of the human brain that were then dramatically distorted and exaggerated.

The left-brain-right-brain theory originated in the work of Roger W. Sperry, who was awarded the Nobel Prize in 1981. He studied brain functioning in patients who had their corpus callosum (the structure that connects the two hemispheres of the brain) surgically severed to treat refractory epilepsy.

However, these patients also experienced other symptoms after the communication pathway between the two sides of the brain was cut. For example, many split-brain patients found themselves unable to name objects that were processed by the right side of the brain but were able to name objects that were processed by the left side of the brain. Based on this information, Sperry suggested that language was controlled by the left side of the brain.

Generally speaking, the left side of the brain tends to control many aspects of language and logic, while the right side tends to handle spatial information and visual comprehension.

Left Brain vs. Right Brain Research

Later research has shown that the brain is not nearly as dichotomous as once thought. For example, research has shown that abilities in subjects such as math are strongest when both halves of the brain work together.

Today, neuroscientists know that the two sides of the brain collaborate to perform a broad variety of tasks and that the two hemispheres communicate through the corpus callosum. "No matter how lateralized the brain can get, though, the two sides still work together," science writer Carl Zimmer explained in an article for Discover magazine.

"The pop psychology notion of a left brain and a right brain doesn’t capture their intimate working relationship. The left hemisphere specializes in picking out the sounds that form words and working out the syntax of the phrase, for example, but it does not have a monopoly on language processing. The right hemisphere is more sensitive to the emotional features of language, tuning in to the slow rhythms of speech that carry intonation and stress."

In one study by researchers at the University of Utah, more than 1,000 participants had their brains analyzed in order to determine if they preferred using one side over the other.

The study revealed that while activity was sometimes higher in certain critical regions, both sides of the brain were essentially equal in their activity on average.

“It’s absolutely true that some brain functions occur in one or the other side of the brain. Language tends to be on the left, attention more on the right. But people don’t tend to have a stronger left- or right-sided brain network. It seems to be determined more connection by connection," explained the study's lead author Dr. Jeff Anderson.

So while people are often described as being either right-brained or left-brained, the truth is that they are actually both. While the idea of left-brain vs. right-brain thinkers has been debunked, its popularity persists.

Persisting Myths of the Left Brain vs. Right Brain

Researchers have demonstrated that left-brain/right-brain theory is a myth, yet its popularity persists. Why? Unfortunately, many people are likely unaware that the theory is outdated. In fact, the idea seems to have taken on a mind of its own within popular culture.

From magazine articles to books to online quizzes, you are bound to see information suggesting that you can unleash the power of your mind if you just discover which side of your brain is stronger or more dominant.

Today, students might continue to learn about the theory as a point of historical interest—to understand how our ideas about how the brain works have evolved and changed over time as researchers have learned more about how the brain operates.

While over-generalized and overstated by popular psychology and self-help texts, understanding your strengths and weaknesses in certain areas can help you develop better ways to learn and study. For example, students who have a difficult time following verbal instructions (often cited as a right-brain characteristic) might benefit from writing down directions and developing better organizational skills.

Clinical psychologist Rachel Goldman, PhD, FTOS recommends that we take time to think about our unique strengths and traits and think about what areas we may want to work on or improve. "We can all benefit from improving our brain health, but first we have to identify what may be working for us, or not, and what areas we may want to exercise in order to make them stronger," she explains. "The great news is that we can improve our brain health, build on our strengths, and create new ways of thinking and doing—it just takes identifying it and then practicing it!"

Rachel Goldman, PhD, FTOS

We can all benefit from improving our brain health, but first we have to identify what may be working for us, or not, and what areas we may want to exercise in order to make them stronger.

The important thing to remember if you take one of the many left-brain/right-brain quizzes you will likely encounter online is that they are entirely for fun, and you shouldn't place much stock in your results.

Improving Brain Health Whether You Feel Left-Brained or Right-Brained

Whether you feel like you tend to be more of a creative type or an analytical type, there are things that you can do to keep your mind sharp and your brain healthy.

Get regular exercise : Research has found that exercise has a protective effect on cognition and brain health as people age.
Keep your mind active : Studies found that people who are mentally active and work in mentally challenging fields, such as academics, tend to have better brain health.
Socialize : Social support is important for psychological well-being, but it is also essential for the health of your brain, particularly as you age.
Eat a healthy diet : The foods you eat can also impact your brain's health and function. Focus on eating a balanced diet focused primarily on fruits, vegetables, lean proteins, healthy fats, and complex carbs.
Get enough rest : Sleep is essential to brain health and mental function, so focus on getting enough rest each night. Practice healthy sleep habits and stick to a regular sleep-wake schedule.

No matter what type of thinking you are doing, both sides of your brain are involved. The right-brain, left-brain theory might be inaccurate, but that doesn't mean that understanding your strengths is not helpful. You can also take steps to protect the health of your brain by getting regular exercise, sleeping well, staying social, and putting your mind to use.

Corballis MC. Left brain, right brain: facts and fantasies. PLoS Biol. 2014;12(1):e1001767. doi:10.1371/journal.pbio.1001767

Joseph R. The right cerebral hemisphere: emotion, music, visual-spatial skills, body-image, dreams, and awareness. J Clin Psychol. 1988;44(5):630-73.

Whitehouse AJ, Bishop DV. Hemispheric division of function is the result of independent probabilistic biases. Neuropsychologia . 2009;47(8-9):1938-43. doi:10.1016/j.neuropsychologia.2009.03.005

Goldie J. The implications of brain lateralisation for modern general practice. Br J Gen Pract. 2016;66(642):44-5. doi: 10.3399/bjgp16X683341

Gazzaniga MS. The split-brain: rooting consciousness in biology. Proc Natl Acad Sci USA. 2014;111(51):18093-4. doi:10.1073/pnas.1417892111

Shen HH. Inner workings: Discovering the split mind. Proc Natl Acad Sci USA. 2014;111(51):18097. doi: 10.1073/pnas.1422335112

Gainotti G. Why are the right and left hemisphere conceptual representations different? Behav Neurol. 2014;2014:603134. doi:10.1155/2014/603134

Liederman J. The dynamics of interhemispheric collaboration and hemispheric control. Brain Cogn. 1998;36(2):193-208. doi:10.1006/brcg.1997.0952

Macdonald K, Germine L, Anderson A, Christodoulou J, Mcgrath LM. Dispelling the Myth: Training in Education or Neuroscience Decreases but Does Not Eliminate Beliefs in Neuromyths. Front Psychol. 2017;8:1314. doi:10.3389/fpsyg.2017.01314

Tyndall AV, Clark CM, Anderson TJ, Hogan DB, Hill MD, Longman RS, Poulin MJ. Protective effects of exercise on cognition and brain health in older edults . Exerc Sport Sci Rev . 2018;46(4):215-223. doi:10.1249/JES.0000000000000161

Hotz I, Deschwanden PF, Mérillat S, Liem F, Kollias S, Jäncke L. Associations of subclinical cerebral small vessel disease and processing speed in non-demented subjects: A 7-year study . NeuroImage: Clinical . 2021;32:102884. doi:10.1016/j.nicl.2021.102884

Sommerlad A, Sabia S, Singh-manoux A, Lewis G, Livingston G. Association of social contact with dementia and cognition: 28-year follow-up of the Whitehall II cohort study . PLoS Med . 2019;16(8):e1002862. doi:10.1371/journal.pmed.1002862

Nielsen, JA, Zielinski, BA, Ferguson, MA, Lainhart, JE, & Anderson, JS. An Evaluation of the Left-Brain vs. Right-Brain Hypothesis With Resting State Functional Connectivity Magnetic Resonance Imaging. PLOS One ; 2013.

Rogers, M. Researchers Debunk Myth of "Right Brain" and "Left-Brain" Personality Traits . University of Utah, Office of Public Affairs; 2013.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

school Campus Bookshelves
menu_book Bookshelves
perm_media Learning Objects
login Login
how_to_reg Request Instructor Account
hub Instructor Commons
Download Page (PDF)
Download Full Book (PDF)
Periodic Table
Physics Constants
Scientific Calculator
Reference & Cite
Tools expand_more
Readability

selected template will load here

This action is not available.

1.5: Lesson 1.5: The Brain Dominance Theory

Last updated
Save as PDF
Page ID 20587

“Rainbow Brain” by Muffinator is in the Public Domain, CC0

The next learning theory reviewed in this series is somewhat controversial. It is called the “Brain Dominance Theory,” or, technically, Lateralization of Brain Function. This theory suggests that certain approaches to thinking and learning differ according to the hemispheres, left and right, of the brain. Critics of this theory claim it is the result of pop psychology more than sound science. Indeed, common sense indicates that, of course, we utilize all parts of the brain continually–which is why I like the multi-colored graphic of the brain. It infers a kind of brain symmetry–if not of function, of form.

UNIT 1, EXERCISE 5.1

Based on the information gleaned in the article and in # 1, design two 8 1/2 by 11 inches posters, one for each side of the brain, illustrating the same information as is on the chart, but according to how you think each kind of thinker/learner might design them. For example, the poster for “right brain” thinking/learning might be much more colorful. The student might also think of some sort of paper structure (origami?) by which to illustrate the differences. Enjoy.

UNIT 1, EXERCISE 5.2

An organization chart might help with this exercise:

ACTIVITY R.B. RESPONSE L.B. RESPONSE

UNIT 1, EXERCISE 5.3

1. Answer the following question (no more than about 150 words):

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Publications
Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

Advanced Search
Journal List
Psychol Res Behav Manag

Intuition, insight, and the right hemisphere: Emergence of higher sociocognitive functions

Intuition is the ability to understand immediately without conscious reasoning and is sometimes explained as a ‘gut feeling’ about the rightness or wrongness of a person, place, situation, temporal episode or object. In contrast, insight is the capacity to gain accurate and a deep understanding of a problem and it is often associated with movement beyond existing paradigms. Examples include Darwin, Einstein and Freud’s theories of natural selection, relativity, or the unconscious; respectively. Many cultures name these concepts and acknowledge their value, and insight is recognized as particularly characteristic of eminent achievements in the arts, sciences and politics. Considerable data suggests that these two concepts are more related than distinct, and that a more distributed intuitive network may feed into a predominately right hemispheric insight-based functional neuronal architecture. The preparation and incubation stages of insight may rely on the incorporation of domain-specific automatized expertise schema associated with intuition. In this manuscript the neural networks associated with intuition and insight are reviewed. Case studies of anomalous subjects with ability–achievement discrepancies are summarized. This theoretical review proposes the prospect that atypical localization of cognitive modules may enhance intuitive and insightful functions and thereby explain individual achievement beyond that expected by conventionally measured intelligence tests. A model and theory of intuition and insight’s neuroanatomical basis is proposed which could be used as a starting point for future research and better understanding of the nature of these two distinctly human and highly complex poorly understood abilities.

“ It’s not that I’m so smart, it’s just that I stay with problems longer ” —Albert Einstein

“ The right hemisphere lacks the capacity to generate productive language in over 95% of the population…[therefore most research]…focused on the language capabilities of this ‘typical’ right hemisphere… (p. 132). ” 1 This comment centred on studies of the ‘typical’ right hemisphere in the majority of subjects’ for whom the left hemisphere is language dominant. Right hemisphere language functions were revealed by: commissurotomy, epilepsy lesion resection, hemispherectomy, stroke or in cases of brain injury. This review also listed right hemisphere-dependent processes which parallel left hemisphere-dependent language processes. To name a few would include: visual word recognition, pre-lexical influences on encoding, phonology, orthography, imageability, syntax and semantics, deep dyslexia and letter-by-letter reading. 2 However as with most research before it on this topic all patients were previously severely neurologically compromised . Hence it would be erroneous and inappropriate to use these defective populations for the study of advanced putative right hemisphere cognitive processing modules or ‘traits’. This would be all the more true for those right hemisphere cognitive functions operating at the upper level of complexity responsible for instantiating neurally complex human social interaction and communication. This fact is due to the ostensibly deleterious effects of any neurological lesion on higher cortical functions. 3 The contrary and still widely held neurolinguistic doctrine on right hemisphere language functions is that the dominant left hemisphere alone demonstrates an intrinsic superiority at linguistic mediation. 4 However again many of these old neurolinguistic assumptions consisted of arguments, studies, and theory that were based solely on inherently pathological cases and without the benefit of modern functional neuroimaging technologies.

To advance a more specific hypothesis: Are endogenous differences to be found in atypical right hemisphere localized subjects where strong hemispheric dominance exists that is not complicated by mixed dominance or pre-existing pathology? Strongly atypically localized and unilateral right hemisphere language dominant subjects are the main focus of this article (eg, see Floel and colleagues). 5 The hypothesis here is that the co-association of language along with other novel module combinations to the nondominant hemisphere may precipitate development of emergent higher-order cognitive functions. The hypothesis is based on a dozen case reports of strongly right-hemisphere lateralized subjects with average general ability scores and yet with superior indices of achievement. 5 – 8 A large achievement and aptitude test difference implies that some other ability may be mediating the usually strong correlation of achievement and ability test concordance. Modern functional neuroimaging studies are becoming available which are not confounded by the problem of pre-existing lesions or neuropathology.

Some new structural neuroimaging studies such as diffusion tensor imaging (DTI) are being carried out that allow researchers to examine why a specific neural tract might be expected to divert along a specific neural trajectory ontogenetically and developmentally. These studies may go far in explaining how a specific neural functional architecture could support exceptional instances of intuitive acumen and/or insight in problem solving. For instance, recent DTI studies show that a “ventral semantic stream” consisting of the fast conducting inferior occipitofrontal fasciculus fibers links the occipitotemporal and orbital regions within the dominant hemisphere. This newly discovered tract may play a key role in multiple concept semantic mapping 9 that has been posited in extensive reviews of the right hemisphere’s parsing of complex discourse functions. 10 Incidentally, as we will see this neural tract also possesses spatiotemporal properties that could function as a conduit linking intuition and insight. Complex discourse functions might include for instance mapping the common threads of discussion between articles appearing in a newspaper over the course of a week of publications. Such architectures might be able to synchronize widespread schemas within the cortex and provide a type of “semantic gestalt” along the lines of how perceptual gestalts are put together in the posterior sensory processing cortices. 11

The theory of co-localization and emergent cognitive functions was previously hypothesized by Basso and colleagues. 12 Co-localization suggests that unique combinations and permutations of modules may reside in one hemisphere or another or even perhaps in the anterior or posterior components within a hemisphere. Emergent properties suggest cognitive processes that are qualitatively different from each other, either in terms of structure and/or function. Complete reversibility in the lateralization of cognitive functions has been previously reported. It is however, quite rare 13 and has yet to be studied systematically with functional and structural neuroimaging or even using in depth neuropsychological assessment and longitudinal achievement studies. There are almost no published studies of atypical right hemisphere language dominants subjects where comprehensive neuropsychological assessments were carried out in conjunction with in depth structural and functional neuroimaging studies.

Given the inherent level of complexity in cognitive modules that are based within an entire hemisphere (or that are the product of whole brain volume oscillation of synchronized signals), comprehensive neuropsychological single case studies and field studies of the social aspects of these phenomenon would be most appropriate. 14 Comprehensive cataloguing of single-case studies of such phenomenon in atypical subjects are nonexistent. Participant–observation studies of such putative advanced social signaling communicative abilities in atypically localized subjects cannot be found in the published literature. In addition to the academic and practical implications of atypical localization for cognitive neuropsychology there are profound theoretical implications for neurolinguistics and theories of language ontogeny in humans. Atypical localization cases or unique co-localization scenarios can be instructive in understanding the fundamental and deep principles by which the cerebral cortex is organized, with respect to language in association with other major neurocognitive functions. 15 Basso and colleagues was among the first to note the fruitfulness of such questioning. 12

Hence, given the above, no theory about the organization of language or cognitive function can be considered comprehensive and/or “complete” without inclusion of a theory that accounts for the “anomalies”. Indeed the single case in neuropsychology is enough by itself to tell experimenters and researchers what the human brain is capable of (or not capable of for that matter!) as well as providing for the basis for generalizations to the population as a whole. 16 A full accounting of how these atypical and anomalous cases of right hemisphere language arise should illuminate the genetic, evolutionary, and functional aspects of these complex, rare and emergent properties. A complete accounting of such anomalies in any comprehensive cognitive neuroscience of language should help to establish the upper limit parameters on what constitutes language by nature as well as the natural constraints placed on the development of such linguistic processes. Such studies could be instructive on how normal language evolved and for what purposes language evolved in the first place in ancestral human beings.

From a more mechanistic point of view, Fischer and colleagues specifically enquired how different cognitive and behavioral operations might be related to each other in terms of functional outcome. 13 That is, is it possible that the intrinsic characteristics or cognitive functions of unexpectedly displaced modules transforms as a function of either (i) dislocation, or (ii) co-localization, along with other modules, within an unexpected hemisphere? Is it true that atypicality and anomalous language representation and unique co-localization of other cognitive functions can result in a functional configuration of neural networks that is favorable to the exceptional development of higher-order cognitive functions such as intuition and insight? Can completely unique cognitive or sociocognitive abilities arise developmentally in such anomalous individuals? How would any such rare and new abilities that are sparingly distributed (or patently not even present), in the general population relate structurally and functionally to other abilities such general intelligence or spatial abilities? It is hypothesized that right-ward language localization and unique co-localization configurations are unique and that such cases can illustrate fundamental principles of language organization even in the normal brain.

Organization of this review

In this extensive theoretical overview of the putative higher-order functions instantiated in part by the right hemisphere a diverse selection of cognitive psychological, neurological, neuroradiological, and neuropsychological literature and data will be examined. Initially we will undertake to define intuition and insight in practical, historical and experimental terms. Secondly we will show how intuition and insight are intrinsically nested within social-cultural constructs of society and to notions of collective mind. Thirdly we will show how intuition and insight constructs are related to each other through empirical studies in the cognitive sciences. Fourthly, we will show how nonverbal decoding efficacy appears to be a central construct in understanding intuition as a function of cognitive psychological expertise.

As we will see conscious and unconscious processes and their integration with emotional evaluation will be central to understanding the link between intuition and insight. Focusing almost entirely on contemporary functional neuroimaging studies (eg, functional magnetic resonance imaging [fMRI], position emission tomography [PET] and magnetoencephalography [MEG]) we will discuss the neural correlates of intuition first which may have a more bilateral representation. Then we will discuss the largely right hemispheric networks underlying insight using many of the same techniques. This two-component network likely figures prominently in virtually all complex novel social problem-solving and thus would likely confer selective adaptive survival value. We will then endeavor to briefly summarize how the self may be a central concept mediating between unconscious and conscious mind; and hence between intuition and insight. Carl Jung conceived of the self as representing the quest for unity and integration in personality and he held that the self as a concept was not yet mature until the third decade of life. 18 In Jung’s 1928 theory the “self ” was a midpoint between the conscious and unconscious minds. 19

With this conceptual overview of how conscious and unconscious processes are interrelated we can then focus on the interesting case of how reversed linguistic asymmetry can shed light on many theoretical neurolinguistic assumptions and hypothesized concepts. There is indeed good evidence that a right ventral hemispheric network operates in both intuition and insight mediated in part perhaps by lateralized caudate nucleus and orbitofrontal networks. In the third part of the review we undertake to show how crossed aphasia was the initial impetus for all early conceptualizations of the functions of the right hemisphere. For many contemporary reasons it can be shown that this standard view of the neurolinguistic inferiority of the right hemisphere is now doubtful and should be viewed with scepticism. Praxis lateralization (either in oppositional hemispheres or co-localized within the right hemisphere with language in atypicals) is discussed as an effect perhaps mediated by the posited “right shift” gene. Such a gene might have enabled language production and comprehension for group communication simultaneous with superior unimanual praxis in ancestral conditions.

A hypothetical line of argumentation shows that atypicality may confer adaptive traits and those anomalous patterns of resting state functional lateralization of intuition and insight could be readily explained. A set of subjects with strong rightward language lateralization that demonstrate characteristic intelligence quotient (IQ)- achievement discrepancies are suggested to be examples of individuals with enhanced or heightened intuitive and insightful processing functions. Although this set of atypical subjects is a small sample that has not been extensively evaluated, in the context of the other lines of converging evidence the summary results are provocative. The review ends with a practical discussion for future research studies on this neglected topic. In the first instance extreme individual differences in these sociocognitive functions may necessarily exist with some rather interesting implications. In the second instance there may not only be quantitative differences in performance of such real-world intuitive and insightful sociocognitive functions – but due also to emergent properties – there may be qualitative differences in the functional neural architecture associated with anomalous or atypical subjects. It is also shown how these sociocognitive functions may be currently poorly understood because of the necessity of studying them in interaction within the larger sociocultural milieu as in participant-observation or field studies. This is a highly complex quasi-experimental approach fraught with inherent measurement difficulties as well as concept operationalization problems. There are also more cognitive neuropsychological implications for understanding gender differences, the nature of intelligence, and the proper psychometric assessment of these putative higher-order abilities as well as understanding the functioning of mixed cortical and subcortically-based neural networks. Finally a clinically relevant and practical example of intuitive-insight based acumen from clinical psychology is put forward with an associated specific set of testable assumptions and hypotheses for future research in this area.

Definition of intuition and insight

According to the Oxford English Dictionary, insight is “ … the capacity to gain an accurate and deep intuitive understanding of something... ” 20 Gestalt psychologist and theoretical linguist, Karl Bühler, originally coined the term insight and here it is conceived of as an individual differences variable that people may possess in varying quantities. 21 In contrast to intuition, insight involves a period of incubation of the problem before the recognition of a solution. 22 There is usually the emergence of a specific temporal pattern associated with the solution to the problem as the solution becomes more and more conscious 23 culminating in the ‘aha or eureka moment’. 24 Intuition, in contrast, has been described by Knoblich as “… the ability to understand something immediately, without the need for conscious reasoning. ..” There are key differences between intuition and insight. Intuition occurs instantly and is emotionally laden; it does not have the accompanying verbal, conscious declarative awareness of the final stage of insight. 25 Interestingly, from the point of view of the cognitive and neural systems supporting the two higher-order processes, is the finding that intuition often precedes an actual conscious insight. 26 This stage-like aspect of intuition and insight as conceived of in this theoretical review will be elaborated on in subsequent sections. Bechara and Damasio similarly described intuition as a holistic hunch, “a gut feeling” or a sense of absolute certainty or awareness that a perception is on the edge of awareness. 27 Insight and intuition are variables that should have a normal distribution within the general population.

Finally, a social cognitive neuroscience perspective of intuition has been found incompatible with the self-report of intuitive “cognitive style” exemplified by the Myers–Briggs type indicator (MBTI). 28 In their review of empirical studies focused on the concept of intuition, Hodgkinson and colleagues 29 noted that none of the sensing-intuition scale items of the MTBI assessed affective or behavioral aspects of the concept, as recently defined by social cognitive neuroscientists. 30 Moreover, Hodgkinson and Clarke found that the constructs on which the MTBI are based are theoretically incompatible with Carl Jung’s theory and suggest behavioral predictions which are contrary to central tenets of the theory. 31 This raises questions about its suitability for the assessment of intuition psychometrically and in particularly the construct validity of the MTBI as a whole. Nonetheless in this review Jung’s early writings 19 on the structure of the self per se do play a considerable role in our agentic construct of intuition and insight. Similarly, a major difference then between insight and intuition is the degree to which the two related constructs are declarative/ explicit or nondeclarative/implicit. Intuition is by definition nondeclarative and implicit, whereas insight can be declarative and explicit in memory.

Lieberman’s review on intuition makes important distinctions between the two terms. 30 Thus, intuition differs from the ‘eureka moments’ characteristic of insight:

“ ….sudden insight also seems to rely on nonconscious processes, but when awareness is derived in insight, it is not a judgment, as is usually the case in intuition. Rather, insight is a process where one suddenly becomes aware of the logical relations between a problem and the answer. In the case of intuition, usually there is no insight into the logical relations, but simply an impetus, judgement, hunch, or behavioural response. That said, intuition is the subjective experience of a mostly nonconscious process that is fast, a-logical, and inaccessible to consciousness that, dependent on exposure to the domain or problem space, is capable of accurately extracting probabilistic contingencies...( p. 110–111).” 30

Bruner 32 noted that intuition” ...rests on familiarity with the domain of knowledge and with its structure …” (p. 57) 32 which is a definition congruent with cognitive psychological expertise. Recent work has shown that the ability to intuit is acquired through experience and learning within a specific domain, and indeed appears to be particularly associated with perceptual pattern recognition processes. 29 Highly skilled intuiters have been found capable of holding many sets of patterns pertaining to a domain of knowledge in their immediate memory, along with information about the emotional salience of each piece of information. 33 Hence, the relationship between intuitive behavior and expert experience within a domain of knowledge, is especially germane. For instance, a chess master may hold 50,000 chess patterns in long-term memory. 33 Similarly, as an example, it is hypothesized that veteran homicide detectives may have an intrinsic feel for the truthfulness of a suspect’s story based on the experience of conducting hundreds of previous interviews, and utilizing a collection of techniques. Finally, Ericsson and Charness noted that, consistent with the intuition and expertise within a domain hypothesis, systematic studies reveal that it requires 10 or more years of experience and dedicated practice with skilled apprenticeship, to become a true expert within a specific domain of knowledge. 34 In this sense intuition and expertise both carry with them complex pattern recognition processes, with an intrinsic motor component, the routinization of which suggests a subcortical basal ganglia loci of action.

Social dimensions of intuition and insight

Since intuition and insight both carry with them connotations of significant interaction with the sociocultural milieu a brief review of current research in this area is advisable. Intuition and insight are usually defined in terms of their salience for scientific discovery. Unfortunately this perspective is often associated with a singular person view of history. This view of the origins of intuition and insight fails to encompass the importance of specific cognitive functions in activities of daily living; especially of a social nature. In other words, from a practical and utilitarian point of view, intuition and insight may play an essential role in the pragmatic functions of language and communication. By pragmatics we mean “ …the way that language is used and interpreted while taking into consideration the characteristics of the speaker and hearer and the effects of contextual and situational variables… (p. 175). ” 15 For the detective the way a suspect responds to a line of questioning through gesture or prosody can be interpreted to mean that they are telling the truth or are lying. As we will soon discuss it is such nonverbal decoding of human behavior in face-to-face interactions and perhaps at some distance that may play a central role in any conceptualization of what these abilities are in essence. Interestingly, neuropragmatics or the study of how the brain comprehends and produces linguistic behavior, shares many similarities with the underlying functional neuroanatomical systems associated with intuition and insight. 35 Hierarchical discourse processes and unstated assumptions; indirect requests; figurative, metaphoric and model building language; mentalizing and theory of mind; and neurolinguistic right hemisphere functions are all examples of a neuropragmatic and intuition–insight link. 10

This functional, socially relevant, and practical view of insight and intuition is the one that we propose to utilize for model-building and hypotheses generation in social cognitive neuroscience. 29 In their reviews Hodgkinson and colleagues as well as Lieberman note that intuition and insight offer considerable explanatory power as essential bridging constructs in social cognitive neuroscience. 29 , 30 Intuition and insight seem to be able to bridge the individual psychology of the thinking variables (eg, cognitive science) with the more contextualized nature of social psychology. In this view, the fundamentally social elements of intuition and insight are inseparable from concise definitions of the two terms and their theoretical interrelations. As such they are more truly conceptualized as social rather than cognitive psychological processes. Csikszentmihalyi and Sawyer note that many cultures have words for such concepts as insight, which are by nature exceptional and highly valued within a culture. 36 Moreover, these authors note that basic stages are associated with insight. In the first stage, an insight is associated with a state of mind relevant to a particular topic, or to knowledge which may be known as a developed domain of expertise. Secondly, a moment of realization results as a consequence of the acquisition of new information specific to the knowledge domain. Finally, a quick re-structuring of the model (as in the example of a “semantic gestalt” where the picture fits with many lines of different evidence), is subjectively experienced as new understanding.

When Csikszentmihalyi and Sawyer interviewed objectively determined exceptionally creative women and men (eg, Nobel Prize winners), a characteristic four stage narrative model of interactional factors emerged. 36 The first stage consisted of laborious reading and research preceding the insight. The second stage was a period of idle time usually spent alone, with the critical third stage of the insight occurring almost momentarily. Finally, the fourth stage consisted of the work-intensive fleshing out of ideas, and painstaking elaboration in order to bring the idea to fruition. Hence for these authors the ‘hard work’ that actually precedes insight in scientific and artistic endeavors is usually deeply rooted in interaction with colleagues, and the individual’s internalized understanding of a culturally constituted domain. However from a more practical point of view, it is generally accepted that some individuals develop more expertise in social understanding and socially productive behavior than others. That is, do some people differ, in a manner similar to an individual difference variable, in the amount of raw intuition and insight that they possess in understanding other people? If so, by what emotional, cognitive, and neuropsychological mechanisms could fundamentally socially based raw intuition and insight develop?

In their interviews, Csikszentmihalyi and Sawyer found that creative individuals displayed strong subjective awareness of external social or disciplinary influences with reference to (i) interpersonal contact (ii) strategic considerations, and (iii) awareness of the relevant paradigms. 36 Furthermore they possessed an awareness of the central questions occupying the consciousness of the field, a keen appreciation for the zeitgeist or “spirit of the times”. An additional creative process set of variables uncovered through the interviews was an iterative loop recurring from the individual person (constituting evolutionary pattern of variation) to selection (the field in which the person works) to retention (or the cumulative record), consisting of a communicable symbolic product. Similarly, two levels of insight were discovered. The first mini-insights might occur in the afternoon following relevant reading in the morning. The second paradigmchanging insight was characteristically much deeper and more profound, often with untold implications across many spheres of knowledge. The latter type of insight is exemplified by Darwin’s many years spent analyzing hundreds of previously undescribed species which thereafter culminated in his formulation of the theory of natural selection. The evaluative and elaborative process associated with this deep type of insight involves integration with the discipline and the larger domain of knowledge. In extreme creativity an unintended result maybe the complete overthrow of existing tacit assumptions within and across disciplines. 37

Deep long-term insight and shorter-term mini-insight can further be distinguished on the basis of the type of problem-solving required. 38 A presented problem-solving process occurs over a short-time frame where a problem is known and pre-existing in the domain. In contrast, the discovered problem-finding process is much longer term, typically occurring over years of study and often with ill-defined parameters and types of problems. In cases of discovered problem-finding processes the actual problem may not be recognized (become conscious), until the moment of insight. Incidentally, in this review, as we will discuss, ill-defined problems (and also associated with discovered problem-finding insightful processes), are highly sensitive to right hemisphere prefrontal cortex lesions. 39 Paradigmatic shifts belong to this latter category of insight. When we speak of insight in the layperson’s understanding of the term, it appears that intuition is related to insight specifically through this incubation stage ( Figure 1 ). That is, the incubation stage in discovered problems seem to be based on the random convergence and amalgamation of ideas (or in our terminology “intuitive schemas”) from different disciplines, sometimes facilitated, but not always, by interaction with individuals from those fields. 36

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f1.jpg

A long-term and slow route to creative insight. Copyright © 1995, The MIT Press. Adapted from Csikszentmihalyi M, Sawyer K. Creative insight: The social dimension of a solitary moment. In: Sternberg RJ, Davidson JE, editors. The Nature of Insight . Cambridge, MA: The MIT Press; 1995. p. 329–363.

Hence, due to the sheer difference in time scales and orders of complexity between presented and discovered problems, problem finding creativity will make greater use of subconscious processing. 36 Therefore, the preparation stage will have a crucial social dimension encompassing apprenticeship, mentoring, solitary study and interaction with experts, which is conscious, declarative, social and serial in nature. In contrast, the incubation stage will allow for multiple chunks of dense information units or models to be integrated simultaneously in a generate, test, and predict sequence. In Figure 1 , we can see where in the model intuition will fit. As to be examined in subsequent neuropsychology sections, intuition, with its subconscious and automatic features would be likely associated with subcortical and limbic connectivity. Intuition’s automatic and highly routinized nature would fit within the high processing bandwidth incubation stage, where complex domain-specific models can be generated, tested and evaluated. In this context, deep knowledge and heuristic structures could be fitted and tweaked until a new paradigm emerges into consciousness. The final stage would consist of laborious step-wise experimentation, characteristic of normal Kuhnian science, that brings a concept, idea, or hypothesis to fruition.

In interviews with 100 eminent artists, writers, scientists, and public institution leaders seven prerequisites for longer-term problem-finding syntheses were noted. 36 The creative, insightful individual must have: “ …(i) a thorough knowledge of one or more symbolic domains; (ii) thorough immersion in a field that practices the domain; (iii) focus of attention on a problematic area of the domain; (iv) ability to internalize information relevant to the problematic area; (v) ability to let the relevant information interact with information from other domains at a subconscious level where parallel processing takes place; (vi) ability to recognize a new configuration emerging from this interaction that helps resolve the problematic situation; and (vii) evaluation and elaboration of the insight in ways that are understandable and valuable to the field… (p. 358–359) .” 36 Hence, we can observe that there are already plausible theoretical links between objectively defined intuition and insight, and an examination of some of the empirical data will further clarify our understanding.

Cognitive science, intuition and insight

The eureka or aha moment of insight was aptly described as the illumination stage, 40 and some of the earliest theories of insight directly noted that an insight was often preceded by an intuition. Metcalfe and Wiebe found that noninsight problems (eg, algebra, analytical thinking, logical thinking) were open to accurate self-predictions of performance by subjects, whereas insight problems were not. 41 Similarly, whereas analytical problems were solved incrementally over time researchers confirmed that insight problems were solved with “an opaque leap”. Wallas directly likened this “illumination stage” to a train or sequence of associations which alludes to the role of motor sequencing in the incubation of intuitions associated with subsequent insight. Incidentally, sequencing has been associated with the integrity of the frontal-temporal lobe 42 and the associated subcortical basal ganglia structures. This sequencing and ostensibly motor nature of incubation of intuitions and their transformations into insight will be elaborated further in subsequent sections of this review.

Dorfman and colleagues suggested that intuition and incubation reflect unconscious processing, which are both aspects of implicit thought. 43 The concept of implicit learning is essential to understanding the illumination stage; and it is defined as any change in experience, thought, or action sequence that is attributable to the acquisition of new semantic or procedural knowledge. This acquisition of knowledge occurs under the conditions of the absence of conscious awareness of that knowledge. In implicit cognition studies there are two related important constructs: the objective and subjective threshold. The objective threshold is the point at which differential motor response to a stimulus disappears, considered as an objectively defined Skinnerian “emitted” motor threshold. In contrast the subjective threshold is the point at which the stimulus cannot be consciously perceived, usually as indicated by verbal report. Deep semantic processing is possible for stimuli presented at subjective threshold, whereas the motor response associated with objective threshold usually is associated with shallow perceptual processing. 44

Experimental evidence that intuition is directly related to insight is chronicled in many studies. 45 The remote associates test is the classic example of insight problem solving 46 however it has also recently been used with much success to study intuition. 47 , 48 In the remote associates test or RAT word triads are presented to subjects such that the three words are semantically related to each other in terms of a common fourth target word. Typically, this fourth target word is activated automatically through spreading activation of semantic networks which converges through summation priming on the remote associate. 49 , 50 Topolinski and Strack have adapted this strategy of the RAT for the objective study of intuition by requiring subjects to simply tell whether they can predict whether the RAT item is soluble or not. 47 This engenders that subjects provide a response before 2000 milliseconds and subjects can actually recollect a feeling of knowing that they either can solve, or not solve, the triad even when they do not know the answer to the triad. Subjects can perform this intuitive version of the RAT task in less than 2000 msec significantly above chance and thus Topolinski and colleagues have succeeded in directly linking intuition and insight in a superb experimental model.

In the first instance, when two sets of remote association items were provided to subjects, purposely only one triad could be solved. 45 In the absence of a solution, a judgment of which triad was coherent or soluble represented only a hunch or intuition. Nonetheless, subjects were able to choose which triads were soluble at rates greater than chance. In the second experiment, sets of remote associate test triads were either semantically convergent (eg, goat, pass, green: solution = mountain) or semantically divergent (eg, strike, same, tennis: solution = match). Congruent with a subconscious semantic priming effect, the semantically convergent triad was more likely to be guessed as coherent or soluble. 45 A third experiment illustrated the potential relationship between pictorial and verbal perceptual matching in the intuition-insight connection. Two types of fragmented objects were depicted in the study. In the first picture a familiar object was fragmented; the second object was rendered meaningless by fragment rotation or displacement. Even when subjects could not name the objects, they reported the correct word well above chance among four presented match options in the meaningful condition.

These experiments demonstrate verbal–verbal and verbal–nonverbal semantic priming in the nonverbal analogues of the RAT as well as evidence of dual hemispheric processes operative in intuition. This semantic priming of intuitive hunches was also replicated for a study of performance on insight vignettes. 45 In this study, the graphical representation of the problem space focused on implicit concepts for the insight solver group and conventional meanings of words for the noninsight solver groups. Thus, multiple lines of evidence support the notion that intuition precedes actual insight, through utilization of subconscious processes. 43 However by what mechanism is this accomplished? It appears that, subthreshold activation of separable knowledge structures, eventuates in convergence on word meanings and is an example of semantic memory priming effects. 43 Hence verbal-verbal (eg, remote associates test) and nonverbal–verbal (eg, fragmented picture and object naming) experiments both illustrate subconscious semantic priming. A perceptual transformation of components, borrowing heavily from Biederman’s recognition by components theory of object recognition, 51 could account for insight problem solving through intuitive processing within the nonverbal domain. 52 There are plausible neural mechanisms to support verbal-nonverbal semantic priming. Tarr found bilateral occipitotemporal activation in subjects’ decision-making involving nonsensical objects, all constructed with similar categorical features. Mental imagery generation also relied on the perceptual occipitotemporal cortex used in such basic object recognition processes. 53

Hence, the essential link between intuition and insight is incubation. Incubation has been demonstrated to occur only after periods of delay, 54 and ability was confirmed to interact with incubation performance effects. This is congruent with the hypothesis that the ability of insightful individuals to piece together the elements of a solution to a problem correlates with their ability to form a confluence of intuitive ideas through incubation. The finding relates directly to our atypical subject hypothesis, to be described below. It was found that only high ability students benefitted from an incubation period during a word solving problem. 55 This suggests that congruent with many previous psychometric studies that there is indeed a reliable and solid correlation between high IQ or measured intelligence and the production of highly “insightful products” (eg, patents, inventions or wealth creation). 56 This evidence is illustrative of an “ IQ threshold ” that occurs for productive incubation, in much the same way that no relationship has been demonstrated between IQ and creativity, beyond an IQ of approximately 120. 57

Nonverbal decoding and intuition

Lieberman provides a comprehensive framework for understanding what intuition is neuropsychologically, and perhaps more importantly, what it is not. 30 Some of Lieberman’s discussions are relevant to the hypotheses examined in this review. Lieberman suggests that intuition is fundamentally the “… subjective experience associated with the use of knowledge gained through implicit learning… (p. 109) .” 30 He directly links intuitive processes with implicit learning mechanisms. Damasio similarly notes that intuition results from cumulative affective reaction(s), rather than the deliberative cost-benefit analysis characteristic of conscious analytical processes. 58 Lieberman further elaborates the long-held view that intuition is closely aligned to social judgment processes, 59 and more relevant to neuropsychology – that it is fundamentally related to nonverbal decoding. “… In the domain of nonverbal decoding, cue sequences are used to gauge the emotions, personality, intentions, attitudes or skill levels of others … (p. 111 ).” 30

In manuscripts discussing intuition since Lieberman, if a commonality is to be found, it is that nonverbal decoding is at the core of a comprehensive understanding of this difficult concept. 30 Nonverbal subtexts underlining communication are numerable; a nonexhaustive list includes: (i) sequencing (ii) facial expressions (iii) prosody (iv) face value skill assessments of others (v) vocal expressions (vi) imitative behaviors (vii) fluency (viii) fluidity (ix) timing (x) tone of voice (xi) blinking (xii) posture (xiii) meaningful and meaningless gesture interpretation and (xiv) gaze direction. 30 Many, nonverbal decoding skills, have been found to rely heavily on right hemisphere networks and substrates. 60 , 61 Similarly, through utilization of modern neuroimaging methods, it was discovered that decision-making about the agentic qualities of body parts and “point light walkers in which the moving joints are illuminated”, consistently activated the dominant inferior parietal cortex. 62 – 71

Nonverbal decoding is extremely pervasive and is the primary means of feedback through which human beings “observe” the mental states of others. 72 Nonverbal behaviors are often more accessible to the people who observe them than the actual producers of such actions. 73 As human beings we are constantly and involuntarily communicating rich information pertaining to our emotional states, our attitudes, and evaluations of situations. Encoding, then, refers to the translation of a mental state into behavioral observables similar to those listed above under nonverbal subtexts to communication. It is becoming increasingly clear that, for the most part, individuals are unaware of their own emotional encoding into nonverbal observable behaviors. 74 In fact, intentional and deliberative management of one’s interpersonal impressions through nonverbal behavior often lead to substandard results compared with the use of intuitive social nonverbal cueing alone. 75 These findings support the existence of a capacity-limited, modular nonverbal encoding neural network, with critical sequencing capacity, which is separable from the declarative memory system.

In his highly influential review, Lieberman suggested five reasons for the similarity between nonverbal decoding and implicit learning. 30 These include the fact that both involve: (i) temporal sequencing and prediction (ii) learning that occurs outside of awareness (iii) the generation of representations and motor skills that are applied absent of awareness (iv) division into judgment and action skill components and (v) dependence on multiple trial learning. Implicit learning figures prominently in these nonverbal decoding experimental paradigms then. However, such paradigms are difficult to explain without actually describing the procedures that are involved and Markovian grammars are a good example. If covariation and frequency detection are at the core of implicit learning, then knowledge of Markovian grammars should provide a case in point of what is actually absorbed at an abstract level in intuition. 76 Markovian grammars are based on a complex set of sequencing rules, motor skill learning, and classification judgments. Hence participants learn probabilistic contingencies among predictors, despite the impossibility of conscious analysis.

For example, on a test trial participants are asked to classify a sequence as grammatical or nongrammatical. Although participants perform at above chance, they report use of intuitive guesswork rather than that of real declarative information. 77 Further studies have discovered that the deep structure of a grammar can transfer to a completely new set of pictorial icons 78 or even across sensory modalities. 79 These simple experiments suggest that intuition has adapted over the course of evolutionary history, to be sensitive to highly invariant, sequential, and causal relationships among variables in the external environment, particularly with respect to cross-modal sensory integration in the nonverbal behavior domain. However, missing until recently, were comprehensive neuropsychological models of the specific neural substrates involved in implicit learning, and hence, also in intuition ( Figure 2 ).

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f2.jpg

Example of a Markovian grammar. Grammatical strings include XV; TLV; TLTPPRJ; XTRLTRJ. Copyright © 2000, American Psychological Association. Adapted from Lieberman MD. Intuition: A social cognitive neuroscience approach. Psychol Bull . 2000;126:109–137.

The basal ganglia degenerative dementias are illustrative of diseases that may be used to understand implicit learning and hence intuition’s neural substrates. Parkinson’s disease is one such model utilized to gain understanding of sequence learning and basal ganglia functioning; since the putamen is affected earlier than the caudate. 80 Moreover, the putamen is connected to motor areas of the cortex, whereas the caudate nuclei are connected to the dorsolateral, orbitofrontal, and anterior cingulate regions involved respectively in working memory; emotion and inhibition; and attentional shifting. 81 This division, along the striatum, led Lieberman to hypothesize that the putamen is involved primarily in nonverbal encoding intuitive social action (eg, production). In contrast, the caudate has a greater role in the nonverbal decoding essential for intuitive social cognitive comprehension. Similarly, Huntington’s disease results from initial destruction of the caudate. 82 Incidentally this atrophy correlates with worsening performance on the Weschler Adult Intelligence Scale (WAIS) and the Wechsler Memory Scale (WMS). 83 Moreover, frontal patients performed normally on probability classification tasks, whereas Huntington’s patients were impaired. 84 This implies that the caudate is a seat of higher cognition.

Nonconscious processing and predictive sequencing also appear to be essential functions performed by the basal ganglia. 30 Skills initially begin as conscious and deliberative, and involve the prefrontal cortex and particularly the medial aspect of temporal lobe. 85 Gradually, with routinization and automaticity, these skills become completely under the control of basal ganglia structures including the striatum, 86 in conjunction with the cerebellum. This also occurs for semantic types of tasks having any type of motor component. 87 As temporal cues involved in sequence learning become increasingly automatized, progressive temporal pattern completion processes results in individuals being unable to determine which early cues could be guiding an intuition. 88 This explains the sublime difficulty of delineating where, when, and how a particular intuition first arose since it progressively becomes automatic and under the control of subcortical motor structures. Intuition is then a property of motor sequencing of nonverbal cues ( Figure 3 ). When pattern completion occurs, the remainder of a sequence can be activated resulting in an overall gestalt emerging from partial data. 89 The pattern completion property of the basal ganglia may explain anecdotal evidence of intuition’s capacity to even predict future behaviors or seemingly inanimate events happening in the distal environment!

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f3.jpg

In the top picture, the four cards used as cues in the Weather Prediction task are depicted. Each card was associated with each possible outcome with a fixed probability. In the table is the probability structure of the task. For each pattern, each card could be present (1) or absent (0). The all-present (1111) and all-absent (0000) patterns were never used. The overall probability of rain, given by summing P (Pattern) *P (rain/pattern) for all patterns, is 50%. Please note that the weather prediction task is not at all like a “ video-gambling task ” since there is a highly complex rule-governed underlying pattern of sequences that can be used to optimize performance much like natural patterns in the external world. Copyright © 2002, Cold Spring Harbor Laboratory Press. Gluck MA, Shohamy D, Myers C. How do people solve the ‘weather prediction’ task?: Individual variability in strategies for probabilistic category learning. Learn Memory . 2002;9:408–418.

Predictive sequencing is exemplified by the serial reaction time task in which subjects determine where a target will appear on a screen. The training paradigm involves the movement of the target through eight repetitive sequences. Over trials subjects implicitly learn the sequence, and during the test trial a portion of the sequence is altered. This enables the examiner to assess how well the sequence was learned. Early Parkinson’s disease patients were found to be impaired on the serial reaction time task, 90 as were Huntington’s patients, 91 while amnesics were found completely unimpaired. 92 Of significant interest was the finding that Parkinson patients’ performance was unimpaired on the task when subjects were directly taught the sequence. 93 The finding implies that nonconscious functions and those associated with predictive sequencing are localized in the striatum. Analogously, caudate activation was recorded during probabilistic classification (eg, the weather prediction task), which did not involve motor response. This illustrates the difference between putamen-motor and caudate-cognitive network attributes. 94 Using Markovian grammars 76 Lieberman and colleagues found that the right caudate nucleus was activated in response to generation of abstract rules of the grammars. 95 Whether there is differential hemispheric caudate activity in other intuitive tasks is a matter for empirical inquiry. Moreover, functional connectivity analyses showed that the right caudate was negatively correlated with activation in the right hippocampus only (r = −0.87) suggestive of hemispheric and lateralized intuitive grammar abstraction processes. 95 Hence, these cognitive nonverbal sequencing tasks are elementally similar to nonverbal decoding functions of the right inferior hemisphere tracts and provide an experimental verification of intuition’s close fit with implicit learning paradigms ( Figure 4 ).

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f4.jpg

The parallel organization of functionally segregrated circuits linking the basal ganglia and cortex. The orbitofrontal cortex and basal ganglia are primary constituents of Lieberman’s automatic X-system associated with the skilled performance and expertise used in intuitive processes. The ventral semantic stream twists through the basal ganglia’s external capsule linking the posterior occipitotemporal cortex with the lateral prefrontal cortex associated with the reflective C-system. Specifically, the right anterior superior temporal gyrus is uniquely associated with insight and the caudate is associated with intuition. In this model the caudate nucleus provides the primary means by which these basal ganglia-dependent (green) and cortical systems (blue) can interact and effectively influence each other. Copyright © 1986. Alexander GE, DeLong MR, Strick PL. Parallel organization of functionally segregated circuits linking basal ganglia and cortex. Annu Rev Neurosci . 1986;9:357–381.

Intuition is primary and insight is secondary

Feeling-of-knowing is perhaps one of the most elaborate accounts of the relationship between objective and subjective indices of knowing. 96 This concept is exemplified by the tip-of-the-tongue phenomenon and perhaps illustrates the temporal sequence of intuition and insight. Feeling-of-knowing is usually conceived of as consisting of metacognitive judgments of ease of processing, 97 fluency, 98 or subjective confidence. 99 Intuition is characterized: 47 by (i) a dim awareness of the processes involved (ii) fast and effortless nature (iii) independence from intention (iv) generation of internal somatic cues such that these processes function to integrate vast amounts of complex information. 100 In a series of 11 elegant experiments it was shown that high fluency gave rise to brief positive fluctuations in affect that emerged into consciousness as a feeling of ease in making coherence judgments of either word triads, visual images, or Markovian grammars. 47 In these studies subjects completed the verbal or image based coherence judgment under time constraints such that explicit verbal answers to the problem had not yet been arrived at – yet a strong feeling of knowing guided performance on the tasks ( Figure 5 ).

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f5.jpg

Although research suggests that presented insight problems do indeed rely on more lateralized right hemispheric processes – the question as to whether longer-term revolutionary insights do as well is open to conjecture and is purely speculative. However, the convergent theme that right hemispheric dominance could accentuate the development of revolutionary insights is borne out by the analysis of atypical subjects and our discussions of three of the most influential intellectuals of the 20th century. For example, Freud developed his theory of the unconscious through uncanny observations about socioemotional functions in his patients and biographers have questioned question whether Einstein had some form of developmental dyslexia (eg, see Heilman for discussions of deep dyslexia). 17 Finally, Darwin developed his theory of natural selection through the integration of huge volumes of information derived from his drawings of different species. Another timely and interesting trend was that this year alone in 2009 five of thirteen new Nobel Laureates were women, the largest number to ever join the ranks in a single year. Copyright © 2009. Adapted and redrawn from Topolinski S, Strack F. The architecture of intuition: Fluency and affect determine intuitive judgments of semantic and visual coherence and judgments of grammaticality in artificial grammar learning. J Exp Psychol Gen . 2009;138:39–63.

Word triads 46 usually attributed to bilateral or right hemisphere functioning 10 were used in the Topolinski and Strack study. 47 Previous studies have shown that reading of the words is usually processed in the left hemisphere; 101 whereas distant or “coarse” concept mapping between words may be the prerogative of the right hemisphere – even in subjects that are not right hemisphere dominant. 2 Judgments of visual coherence in fragmented object contour drawings was taken from the Snodgrass and Vanderwart collection. 102 Processing of whole pictures and visual images is usually considered a property of the integral functioning of the right hemisphere. 103 Hence there is some good evidence to suggest that intuition is content specific involving verbal and nonverbal material and yet that these processes are still temporally and structurally the same. 47 Since these studies used the same archetypal task that is used in insight studies namely the word triads, and generalized these findings to other tasks (object contour drawings and Markovian grammars) 48 , 104 – 106 this illustrates how intuition is primary. This last point is all the more true since the archetypal remote associates task is entirely consistent with more real-world insight tasks. 107

Emotion, affect, and mood in intuition?

The first stage of stimulus emotional appraisal is the distinction between positive and negative affective valence. 108 The basal ganglia appear involved in this initial assessment of positive stimuli; 30 since left basal ganglia lesions reliably result in depression, 109 and because both Parkinson’s and Huntington’s disease 110 often are associated with organic depression. Unipolar depressive disorder is associated with decreased metabolism in the basal ganglia, 111 as well as with significantly increased serotonin binding potential (indicative of decreased serotoninergic tone during episodes), within the striatum. 112 In contrast the amygdala controls bodily responses to aversive stimuli and plays a central role in responding to fear-inducing and negatively-valenced stimuli. 113 Arguably, the basal ganglia (particularly the striatum) and the amygdala comprise two essential way-stations to the positive and negative affective stimulus appraisals typical of the intuitive social cognition system.

Interestingly, female superiority in terms of nonverbal behavior decoding skill 114 and an estrogen-mediated striatal increased performance function on sequential learning tasks, 115 provide empirical and anecdotal corroboration of a biologically based female advantage on many complex intuitive social cognition tasks. 30 These female advantages seem to be manifest in enhanced cortical–subcortical connectivity. Individual differences in the subcortical transfer of semantic-motor information has been hypothesized for some time. 116 In a study of commissural transfer it was found that those with strong leftward hemisphere dominance tended to have smaller areas within the midbody of the callosum. 117 However there is good evidence of neural plasticity and canalization of function through the subcortical and cortical commissures. Marzi and colleagues showed that visuomotor interhemispheric transfer takes place through the parietal commissures in normals, and through the anterior or subcortical commissures in a commissurotomy subject using positron emission tomography. 118 Collectively, then, gender differences in both interhemispheric, and perhaps more provocatively, intrahemispheric subcortical-cortical connectivity, could be worthy of future intuition and insight studies.

At the level of analysis of nonverbal decoding differences, and in the context of social psychology, there are several implications for such individual and group differences. This is illustrated by two well-known theories of social cognition and attitude change. 119 , 120 At the time both theories were heavily reliant on a declarative memory system where it was assumed that declarative memory for counter-attitudinal behavior was essential for behavior-induced attitude change. 30 However, a recent study of attitude change in anterograde amnesics found contrarily that these subjects showed as much attitude change as did control participants. 121 Similarly, a reflected appraisal or “what she thinks he thinks of her” resulted in activation of an entirely right hemispheric network, including the ventrolateral prefrontal and medial temporal cortex, medial parietal lobe, when compared with self-directed appraisal. 122

A right hemisphere based nonverbal decoding advantage that facilitates female intuitive judgments is consistent with all of the above hypotheses. In addition, if the right hemisphere network runs anteriorly and ventrally, extending from the occipitotemporal cortex to the orbital and dorsolateral prefrontal cortex, it is likely to involve the rapid conducting inferior occipitofrontal fasciculus. 123 , 124 Clearly, cortical and noncortical substrates are involved in any contemporary model for emotional interaction in the appraisal of intuitive tasks. For instance, re-appraisal of a strategy for emotional self-control or self-regulation, in which subjects were required to decrease and control negative affect, involved activation of the right lateral orbitofrontal cortex implicated in behavioral inhibition. 125 Similarly, studies have shown that unintentional affect labeling, resulted in increased activity in the right ventrolateral prefrontal cortex, with a resultant inverse relationship between activity in the prefrontal area and activity within the amygdala. 126

Neural correlates of intuition

Lesion studies are not the only means of examining the neural correlates of right hemisphere based nonverbal decoding. One conceptualization of intuition is that it results from the integration of affectively laden gists with unconsciously represented decision-making information. Lesions of the orbitofrontal cortex result in reliable deficiencies in decision-making of this type. 127 Goal valuation is associated with neural activity in the medial orbitofrontal cortex, whereas decision valuation is associated with activity in the central orbitofrontal cortex, and prediction error signaling is associated with reliable activity in the ventral striatum. 128 Hence, orbitofrontally lesioned patients were found unable to integrate emotional and visceral signals into decision-making scenarios. 27 The orbitofrontal ventral neural network hypothesis of intuition and insight will be developed further in a subsequent section.

In one study, participants were presented with fragmented black-and-white line drawings of common objects 26 taken from Snodgrass and Vanderwart’s collection. 102 The task was to determine if the object was meaningful (real object) or non-meaningful (nonobject). Subjects were asked not to name the object, but rather to rely on their gut feeling about whether the pictured stimulus depicted a coherent gestalt. The investigators found activation in the medial orbitofrontal cortex when a fragmented drawing was judged a coherent gestalt. When subjects were asked to individuate objects in a neuroimaging study it was found left orbitofrontal cortex activity 50 msec earlier than activity recorded in the fusiform gyrus. 124 These findings suggest that low frequency information in such drawings facilitates object recognition by initiating top-down processes projected from orbitofrontal to visual cortex. It is possible that a similar right-sided orbitofrontal network exists in right hemisphere dominant individuals.

Again, from a functional neuroanatomical perspective there are specific hypotheses about what white matter tracts would transfer such information. It was proposed that the information being transferred from the orbitofrontal cortex 26 to the inferior temporal cortex utilizes the inferior occipitofrontal fasciculus. 129 By way of digression the ventral occipitotemporal cortex consists of the fusiform gyrus laterally to the parahippocampal gyrus medially; activation in the ventral occipitotemporal cortex was suggested to represent holistic object perception processes. However, it is possible that another route, other than the inferior occipitofrontal fasciculus, conveys part or all of this information. A second possibility would be the inferior longitudinal fasciculus connecting the occipital and anterior temporal lobes, in tandem with the uncinate fasciculus connection from the anterior temporal lobe on to the orbitofrontal cortex. However, it is suggested that this second U-shaped fiber two-way route would be incapable of the required less than 50 msec neural transmission 26 shown to be necessary in Bar and colleagues’s magnetoencephalography study. 124

The second two-way route described above carries visuosemantic information emanating from the temporal pole. 130 Therefore, the inferior frontooccipital fasciculus is likely a primary conduit of the intuitive knowledge network. 26 And functional connectivity analysis demonstrates simultaneous activation within right anterior claustrum, anterior insula, and amygdala. The claustrum is closely associated with striatal functioning and could be involved in synchronization of large-scale whole brain networks. 131 This function would allow an affectively valenced percept to exhibit a characteristic judgmental sense of rightness by temporally linking intuitive processers. Such a clock-like mechanism could also account for the anecdotal findings of a fundamental aspect of intuition which is initiating the correct behavior at the optimal time. Finally, this right hemispheric network extending posteriorly from the right inferior occipitoparietal lobe all the way on to the right orbitofrontal cortex would also be congruent with findings suggesting that these structures constitute a “when or optimal timing pathway” for stimuli within both visual fields. 132

Neural correlates of insight

Intuition, then, is associated with ventral mixed cortical– subcortical interconnected networks extending from the most anterior and posterior reaches of the cerebral cortex. These building blocks of intuition are involved in automatic, nonconscious, and skilled nonverbal decoding especially associated with the right posterior parietal regions. Insight, by contrast, is a conscious and deliberative process at least past the point of restructuring. Recall that restructuring is the rotation of multiple concepts in memory until a semantic gestalt is arrived at that seems logical from any vantage point. Ilg and colleagues used a unique design 133 in which aspects of the RAT 46 were modified so that subjects were required to provide speedy responses. Recall that RAT problems consist of a word triad such as (pine, crab, sauce) and the subject attempts to produce a single solution word (apple). The solution word can form a familiar compound word or phrase with each of the three problem words (pineapple, crab apple, applesauce). RAT and classic insight problems are similar in that these short items (i) misdirect retrieval (ii) solving processes are nonreportable and (iii) elicit aha or eureka responses. 134

These word triads are not as complex as classic insight problems and have advantages of being able to be: (i) solved in short period of time; (ii) have single unambiguous word answers; and are (iii) physically compact for presentation in functional neuroimaging environments. Finally, and most importantly, these “mini-insight” problems are highly correlated with lengthy verbal insight problems. 23 , 107 Therefore given the speeded response in the Ilg study only a subconscious intuitive coherence judgment could be elicited and not an explicit judgment. Recall that the RAT is the abbreviated insight problem of choice where the ‘eureka’ or ‘aha’ experience can be tested for. 10 The condition of explicit judgment (eg, the participants actually picked out the correct RAT) was subtracted from those who made an implicit judgment of coherence condition (eg, an implicit judgment that yes the three words were coherent but that the solution was not conscious). In this intuitive experimental condition, reliable activations were found in the heteromodal bilateral inferior parietal cortex and the right superior posterior temporal cortex. 133

The results of this experiment were unambiguous and confirmed that intuition and insight are related entities. In contrast, increased activation in the anterior right superior temporal cortex was found during sudden insight, 135 using either electroencephalography (EEG) or fMRI. In an insight EEG study, a negative correlation between subjective ratings of the problem restructuring process and the feeling of suddenness of the solution, suggested that restructuring involves an automatic, subconscious recombination of information. 136 – 138 Similarly, the researchers found increased upper alpha band response in right temporal regions, that was interpreted as suppression of weakly activated solution information. 137 Mental impasse was associated with activation in parietooccipital regions in the gamma band and was hypothesized to be associated with inappropriate problem representation and an overload of selective attention. 139 Finally, in trials with high restructuring, decreased alpha power indicative of greater cortical excitation, was discovered in the right prefrontal cortex. Tellingly, both lesion 140 and fMRI 141 studies similarly have shown that restructuring of insight problems involves the right prefrontal cortex as well.

Right hemisphere biases in processing occur when problem solver’s aha experiences are associated with insight solutions and especially with subconscious semantic priming. 142 However the comprehension associated with insight is not completely unilateral. Bilateral anterior superior temporal gyral neural activity has been found to correlate with comprehension of sentences and complex discourse 143 , 144 and these areas are probably recruited during the initial setting of the parameters of a verbal insight problem. Also signal originating in the right anterior superior temporal gyrus during insight problem solving was not due to emotion associated with “aha” because it only increased when subjects first encountered this problem. 135 Revealingly, right hemisphere coarse coding may not be restricted to only nouns since generating unusual verbs to nouns resulted in activity in the right frontal gyri, 145 and comprehending extended discourse resulted in activity in right frontal lobe. 146

This importance of the right frontal cortex in restructuring, associated with insight problem-solving is noteworthy. Frith suggested that of the myriad functions of the prefrontal cortex, ‘sculpting of the response space’ subsumed them all. 147 That is the dorsal lateral prefrontal cortex (DLPFC) is crucial for defining a set of responses, suitable for a particular task, and then biasing these for selection. The matchstick insight problem is another example of a complex insight problem where configurations of matches must be used to solve Roman Numeral type diagrams with explicit rule-based constraints. The matchstick insight arithmetic task is biased by strong constraints, that prevent participants from considering and evaluating the correct solution; 148 and eye movement studies support that problem restructuring occurs by constraint relaxation and chunk decomposition. 24 That is one set of constraints or rules are ignored so that other essential features of the problem can be attended to in sequence (constraint relaxation) and/or chunks of the problem are decomposed into more manageable units (chunk decomposition).

The DLPFC therefore excludes the correct interpretation since normals solved only 43% of the most difficult matchstick problems; whereas 82% of DLPFC patients did. 149 Carlo Reverberi noted this effect was stronger in right DLPFC (pers comm, Sept 2008). Hence, the right DLPFC could have an essential role in constraining the response space of insight problems. This fits assumptions about real world scenarios where preliminary downgrading of all potential possibilities is essential in order to gain traction on a complex insight problem. Hence, a number of generalizations about the functional relationships of intuition and insight include: (i) intuition is associated with nonverbal decoding (ii) intuition is associated with implicit and reflexive processes (iii) insight is associated with conscious restructuring processes (iv) intuition feeds into insight based right hemisphere networks through the right caudate 95 and is modulated by the orbitofrontal cortex. 81 In a very real sense then intuition is primary and insight is only a secondary process that is reliant on the expertise and automaticity of intuition.

Conscious and unconscious processes

If we are discussing the right hemisphere, then surely any examination of superior social cognition constructs like intuition and insight must elaborate on how these processes relate to the weighty topic of the “self ”. It is difficult to imagine concepts like intuition and insight, that that are so lawfully and obviously related to the construct of consciousness, would not also have empirical and theoretical relationships with consciousness’s object, the self. Indeed, many studies using structural, functional neuroimaging, and lesion methods have definitively localized salient aspects of the “self ” to the right hemisphere. 150 The self usually is, after all, associated both in common parlance, and within neuropsychological theory, with the right hemisphere’s emotion and gnostic functions. 61 The UCLA social cognitive neuroscience laboratory similarly has made progress on hypotheses concerning the self’s relationship to intuition, and to a lesser extent insight. In Lieberman and colleagues’ terminology, the C-system (an abbreviation for the C in refleCtive), is implicated in intentional social cognition, which takes effort and is reliant on propositionally organized symbolic representations that can be processed serially, in working and episodic memory. 151 That episodic and working memory function together in the C-system is evidenced in levels of processing research which concludes that greater working memory demand at encoding, results in superior episodic retrieval success. 152 Neural correlates of the C-system include the lateral prefrontal cortex, posterior parietal cortex, hippocampus and the medial temporal lobe structures. 153 Hence, C-system structures are used for evidence-based self knowledge, similar to those associated with propositional reasoning 154 ( Figure 6 ).

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f6.jpg

Neural correlates of the C-system and the X-system displayed on a canonical brain rendering from side ( A ) and bottom ( B ) views. C-system regions displayed are the lateral prefrontal cortex (C1), hippocampus and medial temporal lobe (C2), and the posterior parietal cortex (C3). X-system regions displayed are the ventromedial prefrontal cortex (X1), nucleus accumbens of the basal ganglia (X2), amygdala (X3) and the lateral temporal cortex (X4). Please note that the hippocampus, nucleus accumbens and amygdala are displayed on the cortical surface for the sake of clarity. Copyright © 2004, American Psychological Association. Adapted from Lieberman MD, Jarcho JM, Satpute AB. Evidence-based and intuition-based self-knowledge: An fMRI study. J Pers Soc Psychol . 2004;87:421–435.

A series of ingenuous experiments revealed that the X- and C-systems have definitive relationships with the concept of the self. When participants made self-judgments in domains in which they had little experience, there was strong evidence for the use of episodic retrieval. 155 Therefore, evidence-based self knowledge is not the only means of self-judgment, and it may be limited to those low experience domains of knowledge that subjects have about themselves. In other words if subjects make decisions about themselves in a domain that they have little knowledge they will more often than not use the reflective C-system. In contrast, if subjects make decisions about themselves in domains that they tend to be experts in they will use the X-system. A provocative example is that of patient DB who was permanently amnesic for his entire life, yet was able to make accurate self-referential personality ratings. 156

Thus the X-system (as the X is used in refleXive), automatically collates social and affective variables and produces habitual responses. 151 The X-system consists of the ventromedial prefrontal cortex, basal ganglia, amygdala and the lateral temporal cortex. 157 This research group conducted a fMRI study in which soccer players or actors made self-judgments in a high-experience or low-experience domain respectively. 154 The purpose of the study was to separate the neural substrates of the volitional C-system and the automatic X-system. Subjects made decisions on whether actor or athlete words described themselves accurately. The results showed that self-descriptive judgments from high and low-experience domains were the same for both groups. This finding suggested generalizability across expertise domains and an index of schematicity was computed. The index of schematicity reflected the degree of schema strength in the high-experience domain relative to the low-experience domain. It was predicted that higher difference scores reflected the presence of a more developed schema in the high experience domain. 154 Regions found more active in the intuition-based self-knowledge judgments, associated with the X-system’s high-experience domain, included the left ventral frontal cortex, the left nucleus accumbens of the basal ganglia, the left amygdala, the right lateral temporal cortex and the right posterior parietal cortex. In contrast, the only regions activated with the C-system in nonschematics included the right hippocampus, the bilateral precuneus, and the bilateral dorsolateral prefrontal cortex. 154 The ventromedial prefrontal cortex was uniquely activated by the X-system and the hippocampus was uniquely activated by the C-system such that when subjects made judgments in their high-experience domain, they elicited activation in a network of regions not normally associated with episodic recall or explicit evaluation. However, when assessments were made in their low experience domain, only the lateral prefrontal cortex was differentially activated. 154

Similarly, implicit learning is associated with the unintentional learning of probabilistic relationships between various cues. 158 The increased activity in the basal ganglia and orbitofrontal cortex during intuited self-knowledge are highly consistent with an implicit/explicit memory dichotomy. Ventromedial prefrontal cortex activation was recorded for the implicit association test, 159 providing support for the automaticity-hierarchical delineation. Finally, when nonschematics made intuitive judgments, reliable activation was recorded in the lateral temporal cortex, which has been associated with semantic memory functions. 160 In sum, partial support was found for a combination of implicit/explicit, automatic-controlled processes and episodic/semantic memory involved in intuitive-like functions. However, event-related designs likely would be more helpful in determining what aspects of the neural systems are used in intuition. Hence, the functional neuroanatomy of the intuitive networks implies that the X-system is: (i) affective (ii) slow to form (iii) resistant to and slow to change (iv) insensitive to one’s thoughts about one’s own self and finally (v) insensitive to explicit declarative feedback from others. 154 There is good evidence to suggest that the C-system is relied on only by default in novel decision-making (such as novel insight problems), when heuristic automatic judgments based on associative and intuitive systems are unreliable.

Moreover, the main purpose of the [C-system] is to monitor the [X-system] decisions and correct them when wrong. 161 Other studies suggest that another function of the intuitive ventral frontal and basal ganglia driven X-system is to usurp effortful, analytical processes over time so that comparable automatization benefits can be achieved with minimal efforts. 162 Usurping of cortical functions by basal ganglia subcortical structures is congruent with the known functions of these structures and with previously reviewed striatal skill acquiescence. Congruently consumption of glucose restored effortful C-system functions on a decision-making task following completion of a dual-task paradigm. 163 Thus tired subjects tended to rely on heuristic, automatic decision making strategy, characteristic of the X-system. The caudate of the basal ganglia thus acts like a way-station that directs cognitive activity along automatic default processing networks unless novel stimuli require frontotemporal evaluation of conscious analytical signals processed for affective valence in orbitofrontal cortex. 124

A right hemisphere ventral network in intuition and insight?

An example of a pervasive type of intuitive social cognition is that of the use of scripts, and the facility with which one uses these tools determines in part one’s level of social competence. 164 Scripts are over-learned narratives that indicate a culturally agreed upon order of events in social episodes. Scripts have a core feature of sequencing of gestalt nonverbal actions. These tools allow inference behavior that may not have been directly witnessed and thereby can be used by intuition or insight to infer mental states. Scripts are similar to structured event complexes associated with the functional social purposes of the prefrontal cortex. 165 A structured event complex contains macro-level information relevant to past and current behavior through the storing of events that occurred in the past, and may be likely to occur again in the future. Each structured event complex stores both the theme and the boundaries of events assigned to it. However it does not simply re-represent words and objects stored in posterior association areas of the brain. A structured event complex enables flexible encoding of input allowing for inference and generalization and it stores events that are temporally bound together in close proximity.

A managerial knowledge unit is composed of a series of such structured event complexes and are based on: (i) sequencing (ii) flexibility in sequencing (iii) problem constraint satisfaction (iv) basal frequencies of sequences (v) durations (vi) contexts of settings for actions and (vii) goal-sub- goal hierarchies. A sequence of agreed upon actions for a dinner date would be an example of a managerial knowledge unit. 165 Judgments of temporal contiguity between adjacent action sequences was found to be a function of activation in the posterior association cortex, whereas goal structuring of scripts was found to be a function of the prefrontal cortex. 166 Script generation versus execution errors in dysexecutive patients was consistent with a caudate, rather than a putamenal link in cognitive function. 167 Likewise, the right inferior frontal gyrus was activated in a script ordering task, 168 while right orbitofrontal cortex damage resulted in impairment in the accessibility of scripts, as well as in the semantic representation of social activities. 169 Developmentally we can see the linking of nonverbal sequences in the right occipitotemporo-parietal regions with abstractions of these nonverbal sequences in the form of scripts in the right orbitofrontal cortex.

Huntington’s 170 and Parkinson’s patients demonstrated script sequencing deficits. 171 Given the ventral loci of the right orbitofrontal script reading neural network, parallels can be drawn to a recently described “ventral semantic stream”, present within the right hemisphere. 172 The pathway joins the posterior and superior temporal areas with the inferior and dorsolateral prefrontal cortex, through the inferior occipitofrontal fasciculus. The fasciculus narrows at the junction of the frontal and temporal lobes and passes through the anterior floor of the external capsule of the ganglia, with terminal radiations reaching the middle and inferior temporal gyri and traveling without interruption to the lingual and fusiform gyri. 123 We can see then that these fasiculi could possibly allow ready connectivity between posterior nonverbal decoding networks and the automatization associated with striatal networks moderated by context information within the right orbitofrontal regions.

Electrostimulation anywhere within this fasiculi resulted in semantic paraphasias. 172 Semantic paraphasic errors are exemplified by labeling a presented object such as a “banana” as a “hammer”. We have previously reviewed how coarse, sparse or distant semantic mappings are an intrinsic property of the right hemisphere. Given inferior occipitofrontal fasciculus proximity and connectivity to the orbitofrontal cortex, it is hypothesized that the ventral right hemispheric rapid conducting pathway links the right inferior posterior parietal nonverbal decoding regions with the rostral cognitive script interpreters associated intuition and insight. When comparing novel gesture interpretation or naturalistic action in the right inferior parietal lobes, 173 with the interpretation of scripts in the right orbitofrontal cortex, 168 , 169 there is a clear anterior-posterior demarcation in complexity of the social psychological functions. This ventral right hemisphere network appears to be essential in intuition and insight for many strong empirical cognitive science, neuropsychological, and anatomical reasons previously reviewed. Yet the true test of such a hypothesis would be to carefully examine such hypothesized right hemisphere dominant patients using structural and functional neuroimaging as well as comprehensive neuropsychological assessment. In the past the only way that such patients would be found would have been through the rare occurrence of a small localized stroke within either Broca or Wernicke’s area in the right hemisphere without any attendant secondary dementing processes or confound present. These cases are exceedingly rare.

Crossed aphasia from the historical perspective

Before the era of functional neuroimaging, studies of crossed aphasia provided the only means to examine inferences regarding the nature and organization of atypical language and spatial functions when localized to the right hemisphere. In the most comprehensive meta-analytic study to date, of crossed aphasia in dextrals, Marien and colleagues found that 65% demonstrated constructional apraxia; 39% demonstrated both constructional apraxia and visuospatial neglect; 8% showed visuospatial neglect but not constructional apraxia; and finally, 26% demonstrated constructional apraxia without visuospatial neglect. 174 This meta-analysis revealed that there is considerable heterogeneity in the type and location of different modules within the nondominant hemisphere in crossed aphasics. If there is a near random distribution in which these and other cognitive functions can be localized in one hemisphere or the other, as well as co-localized together in different combinations, then this principle provides some circumstantial support for the hypothesis of the possibility of emergent properties that are qualitatively different than individual components themselves ( Figure 7 ).

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f7.jpg

Archetypal configuration of specific co-localized cognitive modules in normally represented lateralization of functions subjects. In Marien and colleagues’ 174 study of crossed aphasics with singular right hemisphere lesions a secondary analysis was undertaken. Buccofacial praxis was correlated with limb praxis (r = 0.41, P < 0.01) and writing (r = 0.39, P < 0.05). Limb praxis was correlated with writing (r = 0.67, P < 0.001) and visuospatial functions (r = 0.40, P < 0.05). Finally, visuospatial functions were correlated with constructional praxis (r = 0.35, P < 0.05). Copyright © 1991. Adapted with permission from Fischer RS, Alexander MP, Gabriel C, Gould E, Milione J. Reversed lateralization of cognitive functions in right-handers: Exceptions to classical aphasiology. Brain . 1991;114:245–261.

Moreover, the incidence of constructional apraxia was greater than threefold the incidence of visuospatial neglect, and visuospatial neglect occurred at less than 10% in the sample. Since visuospatial neglect is the sine qua non of “crowding”, the low incidence where there is increased lateralization of cognitive processes, can readily be interpreted as strong evidence contrary to the crowding hypothesis. Crowding suggests that with co-localization of language and spatial functions to the right hemisphere there is decrements in the performance capacities of both cognitive functions. Yet the high incidences of constructional apraxia suggests that this function often co-associates with other modular functions in these subjects. In other words, the results do not support the assertion that right-hemisphere language always is associated with the crowding out of other cognitive functions, such as that of visuospatial neglect and constructional praxis. In fact, crossed aphasia in dextrals likely constitutes a highly selected sample. Indeed, Marien and colleagues note that although “ …both neglect and constructional apraxia stand out as frequent nonverbal disorders in vascular crossed aphasia in dextrals, often, though not inherently, [do these symptoms] associated with each other… (p. 55). ” 174 Hence, support for the crowding hypothesis, which historically was associated with the neurolinguistic hypothesis that the right hemisphere was communicatively inferior 4 is not borne out by the data.

Indeed in 6 of 10 atypical language localization subjects a complete reversal of linguistic and spatial functions was found, and four alone showed co-extensive language and spatial attention processes. 8 A subsequent study found that right hemispheric language dominant subjects had a greater tendency towards bilateral or leftward dominance for spatial attention suggesting developmental pressures towards complete reversal of linguistic and spatial functions. 175 Some of the best evidence for the basal rates of unequivocal right hemisphere language in the general population would be found in the crossed aphasia literature pertaining to dextrals. 174 Based on 152 cases published since 1975, only 32% could be reliably categorized into crossed aphasia in dextrals after exclusionary criteria such as nondextrality, unilaterality of lesion, no prior premorbidity, illiteracy, second language or presence of ideographic scripts or tonal languages were applied.

This constitutes a mere 48 known cases of verified crossed aphasia in the published literature since 1975. Interestingly, the frequency of occurrence of crossed aphasia in dextrals was compared between men and women, and men outnumbered women by nearly 3:1. The frequency distribution could perhaps provide clues to the inheritance mechanisms of this anomalous pattern of language representation. Specifically, in agreement with prior studies it suggests that an X-linked allele could encode the phenotype in normal healthy individuals. 174 However it is possible that this ratio could be entirely a statistical artifact (and in fact very likely underestimates crossed aphasia in dextral women), since women routinely do not suffer the same degree of aphasic symptoms after unilateral stroke lesions due to the predominance of bilaterality of language localization. Secondly, when compared to men of the same age when women do have strokes that are debilitating they are usually so serious that they are rendered untestable and therefore would be naturally excluded from any such studies. 176

Visuospatial neglect, the sine qua non of crowding, was found more severe in crossed aphasia in dextral women than in men! More detailed studies would be necessary to corroborate this apparent gender-linked finding. Secondly, in noncrossed aphasia there is a preponderance of nonfluent (eg, frontal) as opposed to fluent (eg, posterior) aphasics, whereas, with crossed aphasia, there is an equivalent frequency of such findings. 174 Recall that noncrossed aphasia is the condition when a patient sustains a serious stroke within the left perisylvian language cortex that would be expected to result in either fluent or nonfluent aphasia yet does not – implying by default language localization to the nondominant right hemisphere. This frontality of noncrossed aphasics versus equivalent frequency of frontal or posterior crossed aphasics could be a function of the greater spatial distribution of language localization within the right hemisphere. 2 Incidentally and as expected this neuroanatomical greater spatial distribution of language processors within the right hemisphere educed from the frequency of proportions of aphasic in the crossed and noncrossed varieties agrees with the spatial summation priming and coarse coding hypothesis borne out by neuropsychological studies. 50

Additionally, it was found that typology of crossed aphasia was independent of age, perhaps suggesting genetic determination for the spatial localization since older aged crossed aphasics did not happen to have more serious (eg, global aphasia) strokes. 174 Again this implies that it is the nature of the spatial localization of crossed aphasia per se, rather than some intervening variable such as a pre-existent higher frequency of incidental arteriovenous malformations that is mediating the lateralized effect. Other important findings include that agraphia in crossed aphasics was found to be particularly severe pointing the way to examination of unique language and praxis localization and co-localization scenarios occurring in this population. Finally, estimates of the prevalence of the potential cases of crossed aphasia in dextrals vary. A 4% incidence of rightward language lateralization using transcranial Doppler sonography has been found, 177 and 6% using fMRI. 178 In the context of the exclusionary criteria this would provide a 1%–2% estimate of the general population as unequivocally showing strong right hemisphere dominant language in agreement with earlier surveys. 179

A few points are worthy of mention in regards to crossed aphasia in dextrals and praxis localization. Again, visuospatial neglect was recorded in 43% of males and 57% of female crossed aphasia in dextral subjects. 174 In contrast, either ideomotor or ideational apraxia which is associated with dominant hemisphere functioning, was found in 18% of male subjects and 38% of females. These findings suggest that in well-characterized subjects, less than half of crossed aphasics demonstrate the putative crowding out of other cognitive functions. This is an important point to be considered when analyzing the Marien and colleagues study since crowding is almost taken to be that of a given in conventional wisdom accepted by clinical neuropsychologists. Furthermore, the low frequency of apraxias associated with right-hemisphere subjects, suggests, that in atypicals, there are bilateral parallel distributions, perhaps more so in men or patent co-localization of praxis and language especially in women. Hence in males, praxis and language dissociation subjects may be particularly apt to demonstrate complete mirror reversal in this domain. 180 There is no obvious reason as to why language and praxis would so routinely be parcellated to the opposite hemisphere in atypical or anomalous subjects!

It is likely that multiple genetic polymorphisms impact on the higher-order factor of general ability, and that studies of small population samples with rare high score IQ’s, are unlikely to target specific critically involved genes. 181 In this context, specific cases like that of the right-hemisphere dominant individuals discussed above, could be informative on specific genetic mechanisms involved in normal neurodevelopment, which are likely to be far more numerous and diverse than the generalist genes integral to basic cellular function, memory, and measured fluid intelligence. 181 Congruent with the ‘perception of action’ hypothesis specialization, atypical subjects’ right-hemisphere representations and associated cognitive processes may provide an advantage in complex matching tasks using perceptual recognition and integration of complex motor informational schemas. This memory for action specialization, rather than memory for declarative content as typified by the cognitive processes tapped by traditional IQ tests, could be explained by any number of plausible hypotheses.

There are other reasons as to why in the vast majority of crossed aphasia in dextral subjects might have separate praxis and language localization. By virtue of atypical subject connectivity to bilateral motor response mechanisms, it might be possible for such subjects to demonstrate superiority in complex verbal–motor perceptual matching tasks. For instance, the right hemisphere is known: (i) to elicit broader activation of semantic categories (ii) far greater sensitivity to distant prime-target pairs (iii) involvement in implicit rather than explicit retrieval (iv) usefulness for predictive inferences (v) for application of knowledge (vi) for lengthy latency of activation to primes (vii) for more diffuse and wider interconnectivity (viii) for better use of strategy (ix) for propensity for global aspects of language, and (x) for greater facility for ambiguous discourse. 2 Further consideration of right hemisphere dominant atypical subjects and semantic networks; handedness; unusual praxic co-localization could suggest methods by which these unique subjects could be studied in the future.

Praxis lateralization and handedness in anomalous subjects

Aphasia after right hemisphere damage is greater in left-handers than in right-handers and occurs with a frequency of approximately 30%. 182 As Alexander and Annett hypothesized: 183 “ …The [rights shift theory] proposes to explain the typical pattern of cerebral asymmetry and normal variations as due to the presence and absence of a single gene (rs+). This gene confers some relative advantages on the left hemisphere which induces the left side to serve speech and also gives a relative advantage to the right hand. It does not determine handedness, but it shifts a chance distribution of handedness toward dextrality. In the absence of the gene (rs – genotype) lateralizations of language and of handedness, and presumably of all other lateralized functions, occur by chance (p. 216). ” One assumption pertaining to this hypothesis is that in the population of such subjects, all possible configurations of cognitive modules should be found.

Most subjects then with right hemisphere dominance for language show left-hemisphere lateralization for praxis; an uncommon dissociation the reason for which appears unknown. 174 It is possible that evolutionarily such a dislocation might have enabled accurate unimanual throwing whilst conversing with other group members. This hypothesis would suggest that language and visuospatial mechanisms would be parcellated into opposite hemispheres. Ninety-two percent of crossed aphasics showed evidence of this pattern. 174 One survey of 73 left-handers with aphasia found that not one subject with right brain damage had limb apraxia. 184 Other studies showed that 70% of left-handed subjects were left hemisphere dominant for language, 17% were right hemisphere dominant for linguistic functions and that only 13% were bilaterally represented. 185 Finally good praxis/language studies of this nature should contain measures of: (i) handedness and limb praxis (ii) language localization and buccofacial praxis and (iii) visuospatial disorders and neglect. 186

Finally, when comparing measures of handedness in women and men, the right-shift was found to be of greater magnitude in women. 187 However, it is noteworthy that, to date, comprehensive quantitative trait loci (QTL) studies of handedness have not been completed. Such studies have the potential to verify which gene(s) underlie handedness and hence linguistic/praxis dominance across the genders. 187 This feminine difference is congruent with the hypothesis that when the RS gene is absent (rs –) in women, there is a higher incidence of random lateralization, thereby precipitating a heightened propensity towards atypical, anomalous, or mirror symmetric localization. Conceivably, this might occur through expression of a recessive trait, perhaps implying a predominant maternal influence in eventual phenotypic expression of atypicality and in strong right hemisphere lateralization. Combined QTL and fMRI would perhaps be able to determine if atypicality is indeed associated with unique co-localization of cognitive functions.

“Resting state” functional lateralization in anomalous subjects

Since the mid-1990’s the right hemisphere has been hypothesized to be the seat of insight. 10 A summary of these early cognitive neuropsychological studies is important because these provided the theoretical basis for most functional neuroimaging insight studies, and its sister cousin intuition, conducted in recent years. Four direct parallels are acknowledged between cognition in insight and the right hemisphere. These include: (1) reliance on nonverbal processes and neural networks; (2) avoidance of functional fixedness or perseveration; (3) access to either nondominant interpretations, larger semantic networks and/or topological similarity in concepts; and (4) perceptual restructuring. 10 Our focus is on insight because (i) it is the more complex and is directly associated with eminent achievement and (ii) it has been neuropsychologically examined over a longer time period. Although; the right hemisphere is unambiguously dominant in insight and to a lesser extent intuitive processes we must stress that such differences are relative rather than absolute. 188 Both the left and right hemispheres are often, but not always, involved in both processes; however the right hemisphere has a dominant role.

Verbal overshadowing experiments confirmed the detrimental effects of verbalization on visual memory, visual image processing, and decision-making. 189 Verbalization impaired subjects’ performance on insight, but not on logical problems, 190 suggesting that insight relies more on nonreportable processes. Moreover, protocol analysis found argumentative structures in logical problems and frequent pauses and lack of articulation associated with insight problems. 107 In a similar manner, “functional fixedness” describes a predisposition to use a tool or object to make a transitive action in a standard manner. In other words, the pre-potent action that an object affords is the dominant action, and not a nonstandard and novel action. However, subjects can learn to use an object in a nonstandard manner that is inconsistent with its more typical use, by overcoming the inherent functional fixedness ascribed to the object. Such cognitive biases persist despite insightful solutions that in hindsight, may appear simple, and may serve to block the participant’s search for alternative solution strategies.

Various concept formation tasks are related to insight problems. Patients with right anterior damage made more perseverative errors than left anterior patients on the Wisconsin Card Sort test. 191 Patients with right, but not left anterior temporal lesions, made more such errors. 192 Patients with right hemisphere lesions made more perseverative errors; 193 as did those with right temporal lobe epileptic foci. 194 Novel and nonobvious alternative solutions to insight problems appear to involve both the right frontal and right anterior temporal structures, with access to nondominant meanings of critical words often essential. In insight often alternative interpretations are modeled by “spreading activation” theories of memory retrieval. 195 Participants who were unable to generate the correct word in a mini-insight problem, exhibited subconscious activation profiles to such an extent that the incorrect guess was nevertheless still related to the correct cue. 196 Finally, the right anterior locus of both perseveration and access to nondominant meanings, are consistent with fMRI studies showing activation during memory retrieval. 197 In addition to allowing for access to multiple meanings, there is evidence that the right hemisphere encodes meaning at a much broader and expansive level. 50 Left visual field presentations resulted in substantially more priming to distantly related words in a divided field paradigm than right visual field presentations. 50 Similarly, the right hemisphere benefited more from interconceptual relations (eg, pear, plum) than from intraconceptual relations (eg, tree, roots). 198 The left hemisphere referents were determined by logical/classificatory links, whereas right hemisphere referents were associated with situational links. Finally, in the left hemisphere there is rapid selection of one meaning and suppression of other candidate meanings, while activation spreads more diffusely and slowly within the distributed right hemispheric semantic network. 199

Consonant with more diffuse activation within the right hemisphere, are findings that the left hemisphere contains more large pyramidal cells. 200 These authors note that: “ …even though both cell-column spacing and dendritic spread change in the same direction within the left hemi sphere, within language-associated regions, they do not change proportionally. Therefore, individual pyramidal cells in each hemisphere contact a different number of adjacent cell columns. In the left hemisphere, this asymmetry results in a smaller number of interconnected columns than in the right, and it has been suggested that this might indicate a more elaborate and less redundant pattern of local processing architecture in the left hemisphere… (p. 431). ” 201 The authors review ample contemporary neurobiological evidence which confirms that differing numbers of macrocolumnar systems, between the left and right hemispheres, allows for differently tuned systems, available to analyze information on a fine or coarse scale.

Perceptual restructuring is analogous to gestalt parallel recognition processes in which an object’s identity is suddenly perceived. There is a direct neuropsychological equivalent to perceptual restructuring. Integrative agnosia is a relatively rare disorder that occurs when a patient has difficulty integrating disparate elements of a display into a coherent singular gestalt form. In this sense, integrative agnosia is the opposite of what occurs during perceptual restructuring. In one of the most comprehensive studies of such patients, it was found that 5 of 7 subjects demonstrated right hemisphere injury (3 of 7 right temporal); half were poor at figure-ground segregation; all were poor at discriminating overlapping figures; and most demonstrated deficits in amodal completion; perception of illusory contours; and in grouping processes. 202 Perceptual restructuring in insight has been shown to be analogous to such perceptual pattern recognition processes. 107 Scholastic Aptitude Test and 11 other potential correlates of successful insight problem solving were analyzed and only object contour drawings and the Embedded Figures Test (EFT) 203 were highly significant predictors. 202 Concurrent verbalization while solving the EFT impaired the ability to make such correct perceptual identifications. 10

There are good reasons to suspect that the habitual processing mode of the right hemisphere is fundamentally different from that of the left. 188 Considerable evidence points to right hemisphere superiority at: imagery, 204 paradigmatic, 205 simultaneous, 206 global, 207 coordinate, 208 parallel, 209 and holistic 11 processing. 210 Baynes and Gazzaniga’s discussion of the left hemisphere “interpreter” also highlights the situational interpretation superiority of the right hemisphere in split-brain patients. 211 Whether similar mechanisms exist in the normal right hemisphere or for that matter in right hemisphere language dominant subjects is open to debate. The interpreter then seeks explanations for why events occur in a “ make it up as we go along ” manner; whereas the right hemisphere demonstrates an acute awareness for more disparate contextual factors, affective reactions as these relate to self.” 211

The difficulty then is determining just what the functions of this right hemisphere are compared to that of this logico-grammatical interpreter of the left hemisphere? Since most normal subjects do not have well-developed linguistic functions in the right hemisphere it is difficult to ascertain just what exactly the right hemisphere is doing compared with the left hemisphere interpreter. Indeed as Baynes and Gazzaniga note; philosopher of consciousness Daniel Dennett’s practical comments on this issue by suggesting that researchers “... accurately assess the upper extent of [right hemisphere] cognitive function... (p. 1355) .” 211 Incidentally, hints into insight problems, presented to the right hemisphere, were solved better. 10 The right hemisphere advantage interacted with a delay, such that the hint effect was substantially larger when individuals were working on the problem unsuccessfully for at least two minutes. 10 Collectively, this suggests that right hemisphere processes are particularly apt to be involved in insight problem-solving, when individuals are stuck in set. The right hemisphere is involved in insight problem-solving, through avoidance of perseveration, access to nondominant meaning and longer-term “problem-finding”.

Relatedly, positive mood has been found to alter preparatory activity within the dorsal anterior cingulate and right angular gyrus and thereby bias participants to engage in processing favorable to insight as opposed to analytical problem solving. 212 Positive affect tips the balance towards global as opposed to local foci of attention 213 and towards broader attention to either external visual space or internal conceptual space. 214 Positive affect appears to heighten solvers’ sensitivity to right hemispheric semantic processing, in conjunction with a frontal-mediated cognitive control network presumably involved in problem restructuring. Recent work on functional lateralization has emphasized the importance of whole hemisphere level coordinative functions of top-down frontal mediated brain networks 215 purportedly involved in the development of right hemisphere language dominance. As an example, the anterior cingulate is involved in overcoming pre-potent responses when conflict is high and strategic processes are less engaged 216 and the right angular gyrus is involved in spatial attention. 217 This right hemispheric network appears to function in the de-selection of pre-potent responses, restructuring of the solution relevant activations and biasing responses towards global internal and/or external attentional loci.

Resting state EGG activity was compared between subjects classified as high insight or low insight using solution rates to anagrams. 218 , 219 Few studies have tested the hypothesis that individuals differ on a factor such as lateralization of function, with the exception of spontaneous undirected thought. 220 An EEG study found that alpha band activity distinguished between individuals with high verbal aptitude and those with high nonverbal aptitude. 221 Verbalizers made greater use of the left parietal regions, whereas nonverbal strategizers made greater use of the right parietal lobe. Correlational analyses supported the position that insight self-reports actually reflected differential use of problem solving strategies, and there was greater bilateral occipital beta (13–18 Hz) indicative of more focused visual attention for low insight subjects. 218 , 219 Hence individual differences in resting state brain activity directly influenced the neural computations associated with insight and this finding is consistent with a diffuse attention mode of highly creative individuals. 222 Greater low alpha at right dorsal-frontal, beta and gamma at right inferior frontal, as well as greater gamma at right parietal was consistent with right functional lateralization in high insight subjects. 218 , 219

Discourse processes, that place a premium on computing distant semantic relations, are particularly apt to result in increases in neural activity within the right temporal lobe, 223 and especially in right anterior-superior temporal lobe. 224 Therefore, the nonverbal nature of intuition and insight suggests a “building block” relationship between the constructs. Intuitive and insightful processes could be used preferentially and habitually, as a function of the fact that they are the preferred cognitive modes for the individual. However, on closer examination, the preferred cognitive mode scenario usually arises as an indirect developmental consequence of specific ability endowment, such as verbal, nonverbal, or spatial second-order factors of intelligence. 225 Alternatively, preferred cognitive mode could be determined by functional lateralization indices. 177 , 226 – 228

Our focus now turns to this developmental hypothesis of the origins of right hemisphere language. Performance on covert visual orientating which is a measure of attentional asymmetry, 229 and the Raven standard progressive matrices 230 was correlated. 231 High asymmetry was negatively correlated with the sine que non measure of fluid intelligence, as measured by the Raven. Similarly an ear advantage in either direction in sinistrals, was associated with lower Object Assembly scores on the WAIS. 232 And more specifically, the achievement-ability domain scores on the Medical College Admission Test were correlated with gender and handedness. 233 Right hemisphere dominance was associated with intellectual giftedness in verbal reasoning and these right-handed individuals scored higher on writing indices. Superior intelligence was associated with stronger recruitment of the bilateral posterior parietal cortex. 234 High IQ has also been associated with bilateral parietal integrity, 235 which re-directs us to the question of the functional relationship between bilateral frontoparietal networks, and the posited ventral right semantic stream associated with intuition and insight.

IQ achievement discrepancy and anomalous subjects

In order to find subjects with strong asymmetry in the direction of the right hemisphere, with little or no bilateralism of functions, large samples of several hundred subjects are required to be sifted through. This search requires that a preliminary method of determining functional lateralization that is cheap and efficient be available. FMRI and PET are too expensive for preliminary first round searches unless the data is associated with a few of the world’s largest functional neuroimaging centers. Even at these centers finding atypical subjects may be difficult since the data may have been collected over decades making it difficult to track down subjects. Also many imaging protocols have not used full brain scans. Functional transcranial doppler sonography or fTCD has been validated in conjunction with intracarotid amobarbitol injection, or the WADA procedure, 226 as well as fMRI 236 for determining the direction and degree of functional lateralization of cognitive functions. Functional TCD constitutes a noninvasive, cheap, quick, and reliable method of determining lateralization in large samples.

Archival fMRI data collected at the Massachusetts General Hospital Functional Neuroimaging Center identified several strongly right hemisphere dominant subjects. 7 These investigators conducted neuropsychological examination of three subjects all of whom happened to be female. A difference in favor of performance IQ versus verbal IQ was found in all three subjects without any history of confounding neurological illness. The investigators noted that in the past the vast majority of patients studied with right hemisphere language had a pre-existing neuropathology. These authors advocated further study in the area, particularly in right hemisphere language dominant women, since most studies have examined ostensibly neurologically pathological individuals. 7 In the Chee and Caplan study, it was noted that both verbal and performance scales were in the normal range for all three healthy subjects. 7 The authors also observed that a complete mirror reversal of cognitive functions occurs in at least a subset of subjects; what this means in terms of adaptive functioning per se is not yet completely understood. Interestingly, the three female subjects studied were professionals or were employed in skilled occupations, requiring high levels of education and advanced post-secondary training. A complete reversal of language and face encoding was found in subject 1, and partial reversal of these functions in subjects 2 and 3. The dislocation of language and face encoding in one subject, and the co-location of face encoding and language in two subjects, provides ambiguous data in reference to the validity of the crowding hypothesis. Z-scores were calculated and pooled across for subjects 2 and 3. The differences in subject 3 in terms of VIQ and PIQ could be interpreted as some support for the crowding hypothesis. 7 , 37 In fact the z-scores for subjects 2 and 3, with incomplete reversal of cognitive functioning, show that when IQ is constant, the only definitive conclusion is that the individuals demonstrated superior Block Design scores, which in contrary to the ‘crowding hypothesis’. All individuals were presumed of superior intellectual ability, given advanced postsecondary achievement indicators ( Table 1 ).

Comparison of complete versus partial reversal of cognitive functions in atypical language lateralization subjects. Copyright © 2001. Adapted and reprinted with permission of Lippincott, Williams & Wilkins, Ltd. from Chee MWL, Caplan D. Face encoding and psychometric testing in healthy dextral with right hemisphere language. Neurology . 59(12):1928–1934

Notes: Bold type indicates potential statistical differences. On the frontal face encoding and the frontal word encoding a positive value denoted left hemispheric dominance and a negative value denotes right hemispheric dominance.

Abbreviations: Educ, education; Hand, handedness; Face Encod, frontal face encoding; Word Encod, frontal word encoding; Mirror Rev, mirror reversal; WAIS, Wechsler Adult Intelligence Scale–Revised; VI Q, verbal IQ; PIQ, performance IQ; BD, block design; DS, digit symbol; Word Mem, word memory; WRMT, Warrington Recognition Memory Test; Face Mem, face memory; Imm Rec Vs, immediate recall (visual); Del Rec Vs, delayed recall (visual); Imm Rec Ve, immediate recall (verbal); Del Rec Ve, delayed recall (verbal); V is Mem I, visual memory index; Ver Mem I, verbal memory index; RORF, Rey-Osterrieth Figure Recall.

Table 1 shows that in partial mirror reversal of lateralization, there was better performance on the Block Design subtest of the WAIS-R when compared with that patient with complete mirror reversal. Block Design is generally considered the best measure of visuospatial perceptual organization in the Wechsler scales, 238 and lesions of the parietal lobes are most prone to result in reliable decrements in performance on this scale. 235 Since performance was greater in subjects with incomplete mirror reversal, in spite of approximately equivalent performance on the VIQ, PIQ, and FSIQ, the findings are congruent with the assertion that crowding is not by any means the norm among these subjects. Usually right lateralization is found for spatial attention, 239 and sometimes neglect is found after left hemisphere lesions in select subjects. 240 No differences in verbal fluency or line bisection performance were found between the left and right hemispheres of atypically localized subjects when compared with those of normal lateralization pattern subjects. 8 Unfortunately this sample recruited preferentially nonright-handers, unlike the Chee and Caplan study, 7 and this added additional complexity to the interpretation of their results. 8 However, a secondary analysis assists in clarification of the mechanisms operating within these data. Table 2 shows that among right-handers, there was a greater number of males with complete mirror reversal and those members exhibited a greater degree of mirror reversal. Whether this pattern holds for larger samples would depend upon an analysis of more right hemisphere dominant dextrals ( Table 2 ).

Handedness and frequencies of demographic, lateralization and performance parameters 8

Notes: Bold type indicates potential statistical differences. Positive values for language and attentional lateralization denote left hemispheric dominance whereas negative values denote right hemispheric dominance.

Further analysis of the subset (n = 4/10) with incomplete mirror reversal, may help clarify this pattern of results found among the largest subset of subjects with demonstrated unambiguous right hemisphere language. To this end then, the short form of the German IQ test (Leistungsprufensystem [LPS]) for adults aged less than 50 years, was used to test general intellectual functioning. 241 The detailed study revealed that two medical students, a teacher, and a business consultant scored within the first standard deviation unit on an equivalent WAIS-R FSIQ measure which is surprisingly low. One female medical student who was right-handed, scored highest on LPS reasoning as well as on the degree of right hemispheric language lateralization. The superior achievement indices of physician, business person, and teacher suggest that these unique subjects possess a type of cognitive advantage in a specific ability as opposed to that of IQ. 242 Collectively, these findings contradict the crowding hypothesis but do point to the puzzlingly low FSIQ indices in some subjects. Finally, in the earlier study by Knecht and colleagues, upon which this study was based, in a atypically localized sample of subjects (n = 21 of 326), no correlation was found between FSIQ and language lateralization. 227 Across the full-range of laterality indices, one striking finding was that a subject with the most extreme rightward lateralization index, also scored highest with an IQ of greater than 150. The latter finding suggests that aptitude-achievement discrepancies are not necessarily the norm, in such atypical subjects, but rather could involve more complex factors (eg, co-association or compensatory development of alternative specific abilities or capacities). However, it is becoming increasingly clear that atypical language dominance is not by any means intrinsically pathological as (i) classical neurolinguistic theory (ii) conventional clinical neuropsychological wisdom or (iii) older empirical studies would suggest ( Table 3 ).

Handedness and frequencies of demographics, lateralization and performance parameters for 4 subjects with incomplete mirror reversal. Copyright © 2001. Adapted and reprinted with permission of Lippincott, Williams & Wilkins, Ltd. From Floel A, Knecht S, Lohmann H, et al. Language and spatial attention can lateralize to the same hemisphere in healthy humans. Neurology . 2001; 57:1018–1024

Note: Bold type indicates potential statistical differences.

Abbreviations: FSIQ, Leistungsprufsystem (LPS) Full-Scale IQ; Lang. Lat., Language Lateralization; Att. Lat., Attentional Lateralization; Incomplete Mirror R., Incomplete Mirror Reversal; LPS V.K., LPS Verbal Knowledge; LPS W.F., LPS Word Fluency; LPS V.P., LPS Visual Perception; LPS Figure-Ground, LPS Figure-Background Perception; LPS Flex. of Closure, LPS Flexibility of Closure; WAIS-R D.S., Wechsler Adult Intelligence Scale – Revised Digit Span Subtest; Corsi Block Span, Corsi Block Tapping Span; Trail-Making A/B, Trail-Making Test Part A (Cognitive Speed) and TMT Part B (Mental Flexibility) Combined Score; Speed-Accuracy, Concentration: Speed/ Accuracy d2 test; Finger Tapping (RH), Finger Tapping Praxis Localization using the Right Hand.

Communicative superiority and functional lateralization?

These early descriptive and qualitative studies constitute very small samples however these are nonetheless quite provocative. The functional significance of these atypical and anomalous subjects’ patterns of laterality is still largely unclear. Knecht and colleagues conducted an elegant functional MRI study of seven left hemisphere and seven right hemisphere language dominant subjects. 228 A uniform and reliable finding was that there was no evidence of increased bilaterality of linguistic functions in right hemisphere-dominant (RHD) subjects. More telling was that no more variability was found in the loci of activation in RHD subjects. The last conclusion is significant since it runs contrary to several developmental psychopathology accounts of the origins of extreme RHD. 243 In other words, the two patterns of spatial topography of hemispheric activation, were completely mirror symmetric. Similarly, there was no evidence of the compensatory bilateral activation that might be expected on the basis of studies of early injury to cortical or mixed cortical/subcortical regions.

When flipping the activation patterns for left hemisphere-dominant (LHD) and RHD and using comparisons, no differences in either the first or second fMRI activation profiles were found, which are results that supported the mirror hypothesis, at least for healthy normal RHD subjects. In fact, for strongly RHD subjects there was greater right lateralization of linguistic processes than was found for leftward lateralization in LHD subjects! Finally, the review by Woods and colleagues suggests that complete shifts of cerebral lateralization only occur after early and extensive cortical and noncortical structural or functional lesions. 243 Such a pathological hypothesis and hence pattern would be expected to be associated with spatially disorganized mapping. However, the subjects in this study exhibited normal structural and functional MRI scans, as well as normal mirror symmetry. Since the 14 subjects were recruited from a consecutive normal population sample of 326, the findings were interpreted by the European Munster Functional Imaging Study group as strong evidence against the early pathology account of RHD.

Developmental neuropsychological studies are of a similar opinion that anomalous patterns are determined genetically and may arise in the uterine environment. 244 Recent studies examined, not only the typicality of linguistic lateralization in right hemisphere dominant individuals, but also the theoretically important issue of the co-dominance patterns of association in these rare subjects. Floel and colleagues’ study was among the first to examine the spatial topography, hemisphericity, and intrahemispheric activation pattern of spatial attention in RHD. 5 The left intrahemispheric activation pattern for spatial attention was found homotopic, with regular spatial topography of activation for right hemisphere dominant spatial attention processes! Secondly, the authors discovered that in RH co-dominance subjects, the pattern of spatial attentional activation did not differ from subjects with right hemisphere dominance for only spatial attention or language! Finally, it was observed that RH co-dominance subjects in the study had no appreciable impairment in cognitive functioning. Consistent with the spatial topography of intrahemispheric RH language, the results suggest that it is the “intrahemispheric pattern”, rather than the hemispheric side per se , that appears to be a hardwired pattern of brain organization. These convergent finding contradicts the leftward language acquisition device doctrine. 4

Practical applications of intuition and insight

Perhaps there are no more requirements for practical application of intuition and insight than in clinical psychological interviewing and assessment. An interesting example of how intuition and insight can be integrated is in the use of projective drawings to examine personality constructs. These sensitive projective tests can also be used to assess more distantly related psychodynamic defense mechanisms in patients and clients. Projective drawings such as the House–Tree–Person have been used in psychodiagnostics for well over 60 years 245 – 247 and can be used for evaluation of psychopathology as well as evaluation of positive aspects of adaptation. Extensive normative and empirical studies are available for all ages and types of diagnosis. Patients are asked to draw a house, a tree, and a person in succession in an open-ended format and then the drawings are rigorously analyzed and scored for various specific test signs and “constellations of signs” usually taken to be indicative of a syndrome. This requires keen observation of the drawings in the context of the referral question, clinical history, other test results and the clinical interview. This is the epitomy of practical intuition of what fits and what does not fit into a clinical picture using a type of “semantic gestalt.”

The three drawings depicted below were drawn by three separate adults. Usually patients will draw the full set of three drawings which each can be scored individually and then similarities in clinical themes across the three drawings can then be used to extrapolate “a configuration of signs”. In the case of drawing A the house is unrecognizable and consists of what looks like a vague floor-plan with logical errors of missing walls and many mis-proportioned segments. These signs are symptomatic of organic brain damage and indeed drawing A was drawn by an adult with severe brain damage. Drawing B depicts two trees drawn in response to the request to draw a tree. The shapes of the trees are decidedly masculine, depicted in a barren environment. The bimodal themes of hills and trees suggest dependency needs in addition to the over-compliance. Drawing C is a depiction of an individual with an extremely distorted body image, with the overall gestalt lines surrounding the face missing and with the macabre instance of intestines spilling out of the figure’s abdomen. This drawing was done by a patient in the throes of an acute schizophrenic episode ( Figure 8 ).

An external file that holds a picture, illustration, etc.
Object name is prbm-3-001f8.jpg

Projective drawings and personality inventory assessment as concordant examples of the relationship between intuition and insight in clinical psychology. Traditionally these projective tests have been used to characterize pathology but increasingly they are also being used to study normal developmental processes and healthy adaptation as in the positive psychology movement. Drawings are particularly apt to tap right hemispheric processes and notions of self, 238 psychodynamic processes, 245 – 247 and as hypothesized in this article links between conscious and unconscious mind. Copyright © 1997. From EH Hammer, Advances in Projective Drawing Interpretation, 1997. Courtesy of Charles C.Thomas Publisher, Ltd., Springfield, Illinois. Drawing A is adapted from Figure 2 –26 on page 34. Drawing B is adapted from Figure 5 – 7 on page 96. Drawing C is adapted from Figure 2 –16 on page 25.

However we must emphasize that in recent years projective drawings have also been used to study factors associated with resiliency, normal adaptation, and positive features of personalities. One particularly excellent way to teach intuition to clinical psychology residents in the art of projectives is to ask the clinician to first get the patient to do the three sets of drawings. Then the individual drawings are scored for the separate House, Tree, and Person criteria. A thematic analysis of trends appearing across the three sets of drawings can then be extracted with usually a summary three line statement about personality structure and any salient defences latent in the drawings. This entire process in rich in projective intuitive interpretation. Note that during the course of the interview and subsequent formal testing the patient is usually asked to complete a standard personality inventory after the drawings: an objective personality test. Once the drawing summary is complete the clinician scores the personality inventory and looks at the degree of concordance between the subjective drawing summary and the objective personality profile. Correlation of drawings with standardized personality tests has been used as a clinical skill development technique since the 1960s. 275 This “secondary insight-based process” is helpful in developing a diagnosis and case conceptualization for the client or patient in the context of referral question, clinical history, interview and the results of other standardized testing. Patient A would be expected to have a generally “flat profile” on the personality scales due to blunting of cognitive functions and general cognitive decline. Patient B would show elevations on measures indicative of dependency and Patient C would be expected to show elevations on somatization and thought disorder scales. Hence the entire process consists of two stages. Stage 1 involves a detailed analysis of the drawings in the context of objective scoring criteria and clinical intuition. Stage 2 involves an insight process that is more reflective in that the clinician takes all of the clinical information about the patient into consideration in formulating a tentative diagnosis, case conceptualization and treatment plan.

In the last five years significant theoretical and empirical developments have advanced the understanding of behavioral, cognitive, and neuropsychological correlates and precursors of intuition and insight. Intuition is the ability to understand something immediately without need for conscious thought; whereas, insight is the capacity to gain an accurate and deep intuitive understanding of something. In popular culture, a link between the concepts has been alluded to. Now, however there are emerging case studies and cognitive and neural research results that add weight to the notion that the two concepts can be considered more sister cousins than orthogonal constructs. There are reliable individual differences found in insight and these differences have been associated with perception of relations and fluency; 248 fluid intelligence; 249 and spatial working memory. 250 Similarly, individuals have been found to vary in intuitive acumen. Differences in nonverbal decoding appear central to most definitions of intuition and they have been recorded across a wide variety of study methodologies. 114 Arguably, intuition often results in decisions that are as good or better than those arising from conscious deliberation, perhaps due in part to its structural properties. 30 , 190 Intuition has been found central to cognitive processes such as heuristic-based decision-making, 251 creativity, 17 and learning. 25 The concept intuition has been correlated with successful and gifted performance in the practice of medicine and has been particularly associated with superior clinical decision-making. 252 Intuition has been a utilized as a construct to explain success in many professions, 253 including specific fields such as nursing 254 and business management. 255 Similarly, using the great minds approach, superior insight has been demonstrated to be pivotal to eminent achievement in many domains. 36

To reiterate, intuition is automatic, nonconscious, affectively laden, absolute and judgmental, instant, implicit, associated with motor response, and the operation of right hemisphere nonverbal decoding mechanisms. In contrast, insight is effortful, conscious, affectively laden only at the moment of restructuring; nonabsolute and nonjudgmental, potentially occurring over longer time spans, declarative, associated with propositional reasoning, and like intuition with the operation of neural substrates in the right hemisphere. Whereas, intuition is associated with the control of expertise and automatized knowledge within basal ganglia and orbitofrontal networks, insight is associated with cognitive functions in knowledge-lean domains, restructuring within the right temporal lobe, and acting in conjunction with frontoparietal networks. It is interesting in this context that the first quantitative morphometric studies of right-hemisphere language dominant subjects only show greater grey matter volume in the right hippocampus. 256 This is consistent with an emerging view that laterality of language localization is a function of maturation of the “what” ventral stream.

While intuition is associated with a single iterative stage, insight is characterized by the four progressive stages of preparation, incubation, insight and elaboration. Functionally and neurally, intuition is closely associated with the development of expertise, heuristics and affective gists during the preparation and incubation stages. The caudate and the orbitofrontal cortex are likely the means through which the two functional neuroanatomical systems interface and computationally interact. Moreover, it appears that intuition usurps declarative knowledge systems once implicit understandings become routinized and automatic via the striatum. Therefore, most perceptual restructuring that occurs during insights’ “eureka” or “aha” moments are a function of subconscious transformation of informationally rich chunks or models. These chunks or intuitive schemas or models have a high throughput band-width which allows for coding vast amounts of information that may be easily modified in the future.

There is anecdotal, empirical, and neurophysiological evidence demonstrating a female advantage on intuitive type tasks involving nonverbal decoding. Also, self-knowledge systems and emotional appraisal are dependent upon effective interaction between basal ganglia and limbic neural networks, thereby demonstrating that self-perception is not completely reliant on declarative memory. Similarly, neuropragmatic tasks like determination of the order of events in social episodes are reliant on right orbitofrontal systems. Other pragmatic aspects of language such as mentalizing or theory of mind (right temporoparietal); 257 , 258 inhibition of one’s own experience during the consideration of another’s state of mind (right ventrolateral prefrontal cortex); 259 self-recognition (right lateral prefrontal cortex); 260 metaphoric figurative language; 261 and indirect requests 10 are similarly dependent on both posterior and anterior right hemispheric networks. Thus, intuition is, in a real sense, primary to insight in terms of the functional interaction of the two highly complex interdependent novel problem solving systems.

Since the right hemisphere is superior at imagery, 204 global, 207 coordinate, 208 and situational as opposed to interpretive functions; 211 intuition and insight in right hemisphere dominant subjects could give rise to “emergent properties.” Utilizing functional transcranial doppler, a European research consortium tested hundreds of subjects for linguistic and spatial localization across the hemispheres. 228 Several dozen female and male subjects, exhibiting extreme levels of right hemisphere language localization were discovered, and interestingly, the magnitude of rightward lateralization was greater than that of leftward lateralization. There was little concordance with the crowding hypothesis, which would have predicted that all subjects have co-extensive spatial and constructional praxis skills in the right linguistic hemisphere. Moreover, subsequent case studies of a cohort of the individuals, many of whom were female, confirmed superior achievement on measures of occupational attainment. This superior achievement was in the context of having recorded mediocre scores on conventionally measured IQ test. The results show gender differences in specific functions as well as perhaps application of gender-specific psychometric testing protocols.

Finally Floel and colleagues’ study of two healthy normal female subjects showed language and spatial functions lateralizing within the right hemisphere using fMRI 5 with no adverse effects on cognitive functioning confirming the co-extensivity hypothesis. 12 , 13 Similarly a 29-year-old right-handed male student demonstrated total lateralization reversal as measured by abstract/concrete word decisions with visually and auditory presented words. 6 The same pattern was found with a visual word generation task and notably cortical and cerebellar foci were mirror symmetric. Since this male subject had no history of brain damage the authors hypothesized that this pattern of brain organization was present from an early age and likely determined genetically. Concordant with this hypothesis, complementary frontocerebellar crossed functions in both left and right language dominant subjects, implies early maturing subcortical influences on the eventual manifestation of hemisphericity for linguistic and spatial processes. 6 Hence, the documentation of co-extensivity of language and spatial processes, as well as unique co-configurations of modules in an unexpected hemisphere, without the necessity of crowding or attenuation of general cognitive functioning, does suggest that emergent cognitive functions is a possibility. That is language and spatial functions could interact in a single hemisphere in real-time with broad affects on the qualitative aspects of cognition that would not be present in normally brain organized subjects.

It is hypothesized that the achievement-ability discrepancies are congruent with speculation that the “functional capacity” of the subjects often exceeds their measured intelligence level. Incidentally, Colom and colleagues found that a right hemispheric network comprising right superior frontal gyrus and right inferior parietal lobule gray matter volume explained most of the variation on measures of working memory capacity in a large sample of individuals within the normal range of intelligence. 262 Arguably, such individuals perform exceptionally well in intellectually demanding environments because, in addition to the regular cadre of cognitive abilities associated with typically localized subjects, the anomalous individuals possess emergent cognitive specializations that normal individuals either do not possess, or do not possess in abundance. The ‘emergent properties’ are hypothesized to be intuition, insight and social competence (and various permutations of these abilities in combination with semantic processing and motor responding), or perhaps “prefrontal-cerebellar inverse modeling mechanisms.” 263

A prefrontal-cerebellar inverse modeling mechanism could provide for the highly accurate mapping of semantic markers and related action concepts to visual gestures by recursive and iterative feedback occurring over ontogeny. 263 It is hypothesized that this would amount to a much more articulate description of categories of human social interaction variables at a high degree of abstraction. 264 As an example universals in sound-shape cross-domain mapping regardless of language, alphabet, or culture suggests that the brain may be similarly involved in extracting a common denominator between vision and movement 265 and could be analogous to a semantic conceptual synaesthesia. 266 A hardwired “crosslinguistic fluency” would aid in dispersal evolutionarily through cooperative behavior and might explain high general IQ 249 and spatial IQ 250 loadings. This would be akin to a tower of Babel effect. Unusual co-localization of language, emotion, and abstract semantics in the right hemisphere, while object-orientated actions and visuospatial functions reside in the left hemisphere could result in the developmental acquisition of emergent properties. In particular, the sequestration of praxis and concrete concepts to the left hemisphere could function as a superior signal-to-noise mapping mechanism, in concert with the right hemisphere’s abstract linguistic mapping function. 267 With this interpretation, the neuropsychological constructs of intuition and insight would be seen at the core of any popularized notion of ‘emotional intelligence’.

The speculation that unique co-localization of cognitive modules, within a hemisphere, could developmentally confer a higher-order sociocognitive function specialization has been considered. In particular, the progression in theory of mind development and its hypothesized core role in virtually all aspects of the elaboration of normal higher-order sociocognitive functioning, 268 as well as its dependence generally on advances in frontal-mediated inhibitory control, 269 is telling. Such posteriorly located core theory of mind and biological motion detection networks within the right hemisphere must develop coherence while under the influence of prefrontal long-range connections. 270 To test such a supposition however would require a systematic identification of subjects and a comprehensive neuropsychological evaluation longitudinally. Additionally, structural and functional neuroimaging would be required, as well as a cognitive neuropsychological analysis of each individual and the group as a whole. This approach would benefit from effective and functional connectivity studies to assist in determining if there were preferential cognitive processing modes associated with intuition and insight.

In summary intuition and insight, in close agreement with the connotation used by the general public and layman, are real psychological constructs at the upper end of complexity in the social cognition scale. Actual human performance is likely to consist of lengthy periods of didactic novice–expert learning of a skill which then becomes routinized and automatic, and is associated with intuition through a domain of knowledge. Similarly, insight is periodically associated with major conceptual transitions within a specific domain of knowledge, and it is punctuated by a regular and normally laborious series of propositional reasoning steps, followed by elaboration. Finally, automatic and subconscious intuitive knowledge feeds into the incubation stage of insight where rich informational chunks are restructured into new understandings. Verbal comprehension and propositional reasoning are examples that demonstrate not all processes associated with intuition and insight are necessarily right hemispheric in origin. Intuition and insight are theoretically well-defined from both a sociocognitive and neural perspective. However, what is required are comprehensive neuropsychological studies directed at determination of the upper performance limits of such functions. Similarly, an understanding of how superior intuition and insight arise over the course of development are nonexistent. As well, further examination of the relationship between intuition and insight to that of other psychometric constructs, such as spatial visualization and general intelligence, are necessary for complete understanding of the area. Finally, improved measures of these constructs in regards to complex social and novel problem solving, are needed.

Conclusions

The neuropsychological study of right hemisphere language functions has been until very recently been plagued by convoluted misinformation, unquestioned and antiquated assumptions and poorly designed research to examine functions of the right hemisphere in neurologically normal human subjects. As recently as the early 1980’s a group of neuropsychologists in Boston and Milan postulated that unique co-localization of cognitive functions within the right hemisphere might possibly lead to the development of anomalous functions. These speculations were not seriously considered until the larger compilations of literature and research were published in the late 1990’s including that original contribution by Beeman and Chiarello. 2 Unfortunately these subsequent approaches studied normal subjects for the most part. Also these studies ignored the fact that with the postulation of anomalous functions was also an assumption (perhaps implicit), in the arguments that given base rates of true unambiguous lateralization these subjects would in all probability constitute a highly selective sample. With the exception of publication of a few contemporaneous empirical studies examining these hypotheses, the research field within this area was silent until a decade later. 117

As the results of this review have shown it is hypothesized that the core anomalous functions that are hypothesized to result from an interaction of high IQ and strong right hemisphere language dominance are exceptional human intuition and insight. Indeed just such cognitive functions or more appropriately “sociocognitive functions” have been postulated to provide a solid empirical and theoretical bridging link between cognitive psychology and social psychological constructs. 29 Incidentally the discovery of mirror neurons (which has been described as the most important discovery in neuroscience of 1990’s), is another bridging link that could ontogenetically speaking augment the development of exceptional intuitive and insightful cognitive functions in atypically localized subjects. 274 As the review notes the original conceptualization of intuition in Jungian terms may be poorly operationalized and it is now recognized that intuition and insight are currently badly conceived psychometrically and need better operationalizations and standardizations. The exception is that intuition may be closely associated with notions of expertise and Lieberman and colleagues have made excellent progress in elaborating the neurophysiological basis of these terms in cognitive neuroscience parlance. 30

We note that because these two terms carry with them considerable connotations of “social intelligence” there is good reason to believe that exceptional achievement in scientific, political and/or artistic domains might carry with it such selection effects. Two different types of problem-finding associated with insight are noteworthy in this sense. Presented problems are associated with normal Kuhnian science whereas revolutionary insight is associated with discovered problems of a fundamental paradigm changing, longer-term nature. 37 Hence well-developed intuition and insight can only be demonstrated in a social context and there are ample casestudies of eminent achievements that show that an abundance of intuition and insight constitute essential ingredients of such achievements. The selection hypothesis also raises the question of the essential ecology of the development of such unique social cognitive functions in humans. The cognitive science literature similarly points towards the importance of unconscious processes in intuition and more declarative conscious processes in insight. This substantial empirical research base alludes to some solid models of intuition and insight as well as theoretical development about how these two “cognitive processes” are interrelated.

For many social psychological, systems neuroscience and cognitive science reasons it is then shown that the core attribute of excellence in intuition consists of efficacy in, and well-developed repertoires of nonverbal decoding behavior. Secondly it is shown that there are also many neurophysiological, behavioral, and gender difference reasons to suggest that women possess superior nonverbal decoding abilities on an average case-by-case basis as compared to most men. Particularly, caudate and orbitofrontal connectivity with the rest of the cortex seem to be able to explain a great deal of data pertaining to basal ganglia neurodegenerative studies and the cognitive neuroscience studies of category learning. It is hypothesized then the caudate may function as a critical way-station between conscious declarative insight-based learning and nonconscious implicit intuitive schemas. Moreover it appears that as a skill becomes routinized the caudate-putamen and its cerebellar connectivity “usurps” control of formerly declarative knowledge schemas enabling: (i) automatization (ii) massively parallel processing and (iii) efficiency in the eventual coordination of multiple informationally-rich schemas. It is then shown how intuition is primary to insight.

We then review how mood and emotion variables may be critically linked to the functioning of neural architectures for intuition and insight. Moreover, intrahemispheric subcortical connectivity within anomalous subjects may figure prominently in the expression of these two sociocognitive phenotypes. In particular, a recently described inferior occipitofrontal fasciculus linking the orbitofrontal, ganglia and posterior cortical regions appears to have the necessary spatiotemporal properties to link intuitive and insight neural architectures. 123 , 124 Next the neural correlates of intuition and insight are described. Intuition appears to be dependent on dual hemispheric inferior parietal and caudate structures whereas insight is dependent on right hemispheric temporal and right inferior prefrontal structures. Moreover several key functional neuroimaging studies show the right caudate acts as a way-station directing nonconscious activity along automatic default processing networks unless novel stimuli require frontotemporal evaluation of conscious signals. These signals are simultaneously monitored online for their affective salience in the orbitofrontal cortex. Also this caudate motor skill network is associated with judgments pertaining to “self in high-expertise domains” and thus seems to possess the necessary properties to be associated with ego functions. Finally the use of scripts by subjects in functional MRI and lesion studies illustrates the complex terminal end of the ventral stream within the right orbitofrontal cortex. This ventral semantic stream seems to possess all the requisite neuropsychological properties to function as a fast conduit between posterior right inferior parietal nonverbal decoding networks and anterior right orbital highly specialized social-context parsing neural networks (eg, script readers).

We then endeavor to show that crossed aphasia (eg, subjects with significant right perisylvian lesions and aphasia implying strong premorbid right hemisphere language dominance), was presumably the only means of finding such rare subjects until the first functional neuroimaging PET studies were published in the late 1980’s. It is then shown that recent comprehensive cataloguing of such patients contradicts “the crowding hypothesis”. The crowding hypothesis is traditionally held as a truism among many clinical neuropsychologists and it suggests that with unusual atypical dominance often visuospatial functions are co-extensive with language. As a result of this unusual co-localization the crowding hypothesis suggests that performance in both cognitive function domains is substandard to that of traditionally organized left hemisphere language dominant subjects. Also strong neuropsychological data converge on the common conclusion that language is a much more distributed organization in the right hemisphere with perhaps better situational linkages between concepts represented in a much more distantly-related manner. Next the relationship between hand praxis and atypical language localization is examined with some interesting attending hypotheses about sex-linked patterns of phenotypic expression.

Based on all the arguments and evidence discussed up until this point, the hypothesis is advanced that the resting state of the anomalous subject is biased towards fundamentally different computations that have been sometimes described as: global, coordinate, imagery, paradigmatic, simultaneous, parallel, holistic, and situational. Several strongly right hemisphere dominant subjects identified through carotid Doppler studies were then compared in comprehensive neuropsychological studies with the understanding that this constitutes a small initial sample. Nonetheless in the context of various converging arguments and using diverse methodologies these tentative case study subjects are provocative. Most subjects showed little evidence of crowding with some evidence of disproportioned development of cognitive abilities. Typically IQ was lower than expected (given achievement indicators), in anomalous subjects and the pattern was reliable enough to suggest a trend. Interestingly most of these subjects were women which is congruent with some of the genetic hypotheses previously advanced. It is then hypothesized (although by no means proven), that the reason that these women seem to be able to achieve beyond conventionally measured IQ is that they possess disproportionately well-developed intuitive and insight based acumen. Finally, a model of the interaction of intuition and insight processes in clinical psychology is advanced with the goal of showing how important these sociocognitive functions are in the real-world.

In the final discussion all of the section’s main themes are reviewed integratively with the goal towards to advancing overarching hypotheses as well as testable empirical questions in subsequent studies. The focus is upon determining what these anomalous functions are in the most general sense, as well as why these sociocognitive functions may have evolved, and why they may be so specialized in these rare individuals? We review how the anomalous functions in question seem to have high correlations with both general IQ as well as spatial IQ suggestive of significant intermingling of gene pools. It is shown that high intuition and insight are highly correlated with performance in a host of occupations and that the putative maturation of a right ventral hemispheric “when pathway” is congruent with much recent work in cognitive neuroscience. It is speculated that one of the functions of the development of this neural network would be to facilitate “inverse cognitive modeling” amounting to a neural mechanism for a much more articulate mapping of visual gestures. This would facilitate evolutionarily genetic dispersal as well as enable cross-linguistic fluency and hence facilitate cooperative behaviors across diverse genetic groups. Finally, the unique structure of this well-developed archetypal neural network might also enable highly accurate and precise lexicosemantic mapping of concepts to abstract features of transitive and intransitive human actions through massively parallel integration of information between cortical and subcortical structures.

Limitations

This lengthy review provides one of the first comprehensive neuropsychological overviews in the literature on “intuition” and “insight” as inter-dependent higher-order cognitive and social constructs. However a recent meta-analytic review of popular notions of “creativity” and hemispheric specialization 271 may bridge some of the achievement-ability connections not discussed in depth in this article. It has been proposed that intuition and insight are: (1) individual difference variables with a normal distributions (2) are culturally universal constructs (3) are evolutionary advantageous in terms of making social predictions and generating novel solutions to complex social problems (4) have a hierarchical structure involving various components that are neuroanatomically localized (5) are predominately lateralized to the right hemisphere (6) are facilitated by co-localization with complimentary functions such as those involved in language processing (7) can account for elevated individual achievement in the context of average intellectual abilities, particularly in individuals with right hemisphere dominance for language. It is important to stress that the results of this review are not meant to naively imply that the left hemisphere and right hemisphere processing styles are absolute in nature. 272 Instead for some highly selected individuals the left and right hemispheres may possess relatively greater specialization for certain types of spatiotemporal and semantic processes. The two sides of the brain do not operate independently or in isolation from the computations of the other hemisphere. 188 As with any new foray into the arena of inquiry it is important to stress that this work is meant to facilitate subsequent research and especially further future well-designed empirical studies on the topic.

There is currently insufficient evidence showing how co-localization of cognitive functions within a hemisphere result in either (i) facilitation (as posited in this review) or (ii) interference effects in terms of performance exemplified by the concept of crowding. We have deliberately avoided discussions of crosscultural studies of intuition and insight lest this primarily neuropsychologically-orientated review become unmanageable. There is at present insufficient good measures of intuition and insight and these constructs are at present very poorly psychometrically conceived. We focused on a very small number of studies and in fact the only reason these cases were included was to highlight the usefulness of the systematic neuropsychological study of atypical subjects especially with the rise of advanced structural and functional neuroimaging methods. Also, the cases in question used occupational attainment alone as an indicator of social ascendancy and socioeconomic status and included no measures of social competence, family connections, work ethos, and contemporary motivational constructs. Nor have the base rates of IQ distributions in various occupations been examined. The author has left it to future investigators to discover why if patent right hemisphere dominance is so potentially advantageous why is it also so universally rare? Finally, readers should be aware that even if the hypotheses of a right hemisphere language dominant specialization is not borne out by the data in those subjects with IQ’s in the normal range (eg, 100–120) this does not mean that this hypothesis does not apply to subjects above an IQ threshold or of high IQ. This “ selection effect ” caveat is due to the fact that right hemisphere dominant subjects: (i) constitute a highly selected sample to begin with; (ii) high IQ would allow for more synthetic processes to occur between building blocks of intuition and insight 225 and (iii) the focus of this review is on abilities posited to allow for exceptional human performance currently at the upper bounds of our understanding of social cognition and human inter-group communication processes.

Acknowledgments

Simon McCrea, PhD was a Post-Doctoral Fellow and Research Associate of the Divisions of Neurology and Neuroophthalmology within the Faculty of Medicine at the University of British Columbia for part of the duration during which this manuscript was prepared. The author acknowledges the funding and indirect support of a US National Institute of Mental Health ( NIMH ) R01-MH069898 grant to Jason Barton, MD, PhD during formulation of ideas and writing of portions of this review from 2006–2007. Parts of this manuscript were presented at the VII Annual Meeting of the Vision Sciences Society in Sarasota, Florida from May 11th to May 16th, 2007. The author thanks three anonymous reviewers for their excellent comments. The author reports no conflict of interest in this work.

Encyclopedia of the History of Psychological Theories pp 160–172 Cite as

Cerebral Dominance

Stanley Finger 2
Reference work entry

422 Accesses

The concept of cerebral dominance refers to the functional inequality of the cerebral hemispheres. It does not hold that the right hemisphere controls the muscles of the left side of the body or that it receives the bulk ofthe sensory information relating to the left side, andthat theopposite is true for the left hemisphere. Rather, it relates to differences of adifferent sort – differences incognitive functions such as speaking, consciously comprehending spoken language, and dealing with the spatial world, as exemplified by using amap or trying to draw aclock or ahouse.

The current literature on cerebral dominance is massive and has experienced very rapid growth after the 1950s, stimulated in part by what was being discovered with split-brain patients. It is based on healthy and brain-damaged subjects, and awide variety of tools. Some of the information gained has come from postmortems and other anatomical studies, and even more is now coming from physiological studies, especially...

This is a preview of subscription content, log in via an institution .

Buying options

Available as PDF
Read on any device
Instant download
Own it forever
Available as EPUB and PDF
Durable hardcover edition
Dispatched in 3 to 5 business days
Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Anonymous. (1850). Duality and decussation. Buchanan’s Journal of Man, 1 , 513–528.

Google Scholar

Badal, J. (1888). Contribution al’étude des cécites psychiques:Alexie, agraphie, hémianopsie inférieure, trouble du sens de l’espace. Archives d’Ophthalmologie, 8 , 97–117.

Barkow, H.C.L. (1864). Bemerkungen zur Pathologischen Osteologie . Breslau: Ferdinand Hirt’s Königliche Universitäts – Buchhandlung.

Bastian, H.C. (1880). The brain as an organ of mind . London: Kegan Paul.

Bell, C. (1811). Idea of anew anatomy of the brain . London: Strahanand Preston. (Reprinted in 1936 in Medical classics, 1 , pp.105–120.)

Benton, A. (1976). Historical development of the concept of hemispheric cerebral dominance. In S.F. Spicker & H.T. Engelhardt (Eds.), Philosophical dimensions of the neuro-medical sciences (pp.35–57). Dordrecht/Holland: D. Reidel.

Benton, A.L. (1982). Spatial thinking in neurological patients: Historical aspects. In M. Potegal (Ed.), Spatial abilities: Development and physiological foundations (pp.253–275). New York: Academic.

Benton, A. (1984). Hemispheric dominance before Broca. Neuropsychologia, 22 , 807–811.

PubMed Google Scholar

Berker, E.A., Berker, A.H., & Smith, A. (1986). Translation of Broca’s 1865 report: Localization of speech in the third left frontal convolution. Archives of Neurology, 43 , 1065–1072.

Bichat, F.-X. (1805). Recherches Physiologiques sur la Vie et la Mort (3rded.). Paris: Brosson/Gabon. (F. Gold, Trans. Physiological researches on life and death. Boston: Richardson & Lord, 1827.)

Boller, F. (1977). Johann Baptist Schmidt. Archives of Neurology, 34 , 306–307.

Bouillaud, J.-B. (1825). Traité Clinique et Physiologique de l’Encéphalite ou Inflammation du Cerveau . Paris: J.B. Ballière.

Broca, P. (1861a). Remarques sur le siège de la faculté du langage articulé, suivies d’une observation d’aphémie (perte de la parole). Bulletins de la Société Anatomique, 36 , 330–357.

Broca, P. (1861b). Nouvelle observation aphémie produite par un lésion de la moité postérieure des deuxième et troisième circonvolutions frontales. Bulletins de la Société Anatomique, 2d ser., 6 , 398–407.

Broca, P. (1863). Localisation des fonctions cérébrales. Siège du langage articulé. Bulletins de la Société d’Anthropologie, 4 , 200–204.

Broca, P. (1865). Sur le siège de la faculté du langage articulé. Bulletins de la Société d’Anthropologie, 6 , 337–393.

Broca, P. (1869). L’ordre des primates. Parallèle anatomique de l’homme et des singes. XI. Le cerveau. Bulletins de la Société d’Anthropologie, Ser. 2, 7 , 879–896.

Broca, P. (1875). Sur les poids relatifs des deux hémisphères cérébraux et de leurs lobes frontaux. Bulletins de la Société d’Anthropologie, 10 , 534.

Brown-Séquard, C.-E. (1874a). Dual character of the brain. Smithsonian Miscellaneous Collections, 15 , 1–21.

Brown-Séquard, C.-E. (1874b). The brain power of man: Has he two brains or has he only one? Cincinnati Lancet and Observer, 17 , 330–333.

Brown-Séquard, C.-E. (1890). Have we two brains or one? Forum, 9 , 627–643.

Bruce, L.C. (1895). Notes of acase of dual brain action. Brain, 18 , 54–65.

Bruce, L.C. (1897). Dual brain action and its relation to certain epileptic states. Medico-Chirurgical Society of Edinburgh, 16 , 114–119.

Burdach, K.F. (1826). Vom Baue und Leben des Gehirns (Vol. 3). Leipzig: Dyk.

Caizergues, R. (1879). Notes pour servir à l’histoire de l’aphasie. Montpellier Médecine, 42 , 178–180.

Chadwick, J., & Mann, W.N. (1950). The medical works of hippocrates . London: Blackwell.

Crichton-Browne, J. (1907). Dexterity and the bend sinister. Proceedings of the Royal Institution of Great Britain, 18 , 623–652.

Critchley, M. (1964). Dax’s law. International Journal of Neurology, 4 , 199–206.

Cubelli, R., & Montagna, C.G. (1994). Areappraisal of the controversy of Dax and Broca. Journal of the History of the Neurosciences, 3 , 1–12.

Cunningham, D.J. (1892). Contribution to the surface anatomy of the cerebral hemispheres . Dublin: Royal Irish Academy.

Dax, G. (1865a). Notes sur le même sujet. Gazette Hebdomadaire de Médecine et de Chirurgie, 2 , 262.

Dax, M. (1865b). Lésion de la moitié gauche de l’encéphale coïncidant avec l’oubli des signes de la pensée (lu aMontpellier en 1836). Gazette Hebdomidaire de Médecine et de Chirurgie, 2 (2nd ser), 259–260.

Dax, G. (1866). Correspondance médicale. Montpellier Médicale, 39 , 172–176.

Dax, G. (1875). Note historique sur l’aphasie. Montpellier Médicale, 4 , 368–371.

Dax, G. (1877). Observations tendant à prouver la coïncidence constante des dérangements de la parole avec une lésion de l’hémisphère gauche du cerveau. Montpellier Médicale, 39 , 230–251.

Delaunay, G. (1874). Biologie Comparée du Côte Droit et du Côte Gauche chex l’Homme et chez étres Vivants . Paris: A. Parent.

Descartes, R. (1649). Les Passions de l’Ame . Paris: Henry Le gras.

Eberstaller, O. (1890). Das Stirnhirn . Wien: Urban und Schwartzenberg.

Eling, P. (1983). Comparing different measures of laterality: Do they relate to asingle mechanism? Journal of Clinical Neuropsychology, 5 , 135–147.

Eling, P. (1984). Broca on the relation between handedness and cerebral speech dominance. Brain and Language, 22 , 158–159.

Esquirol, J.E.D. (1838). Mental maladies (E.K. Hunt, Trans.,1845). Philadelphia: Lea & Blanchard (Facsimileed.; New York: Hafner, 1865.)

Finger, S. (1994). Origins of neuroscience: Ahistory of explorations into brain function . New York: Oxford University Press.

Finger, S. (2000). Minds behind the brain: Ahistory of the pioneers and their discoveries . New York: Oxford University Press.

Finger, S., & Roe, D. (1996). Gustave Dax and the early history of cerebral dominance. Archives of Neurology, 53 , 806–813.

Finger, S., & Roe, D. (1999). Does Gustave Dax deserve to be forgotten? The temporal lobe theory and other contributions of an overlooked figure in the history of language and cerebral dominance. Brain and Language, 69 , 16–30.

Finger, S., Gehr, S.E., & West, A.L. (2001). Dual personality and the brain: The case studies of Lewis C. Bruce in the 1890s. History of Psychiatry, 12 , 59–71.

Flourens, M.-J.-P. (1824). Recherches Expérimentales sur les Propriétés et les Fonctions du Système Nerveux dans les Animaux Vertébrés . Paris: J.B. Ballière.

Flourens, M.-J.-P. (1842). Recherches Expérimentales sur les Propriétés et les Fonctions du Système Nerveux dans les Animaux Vertébrés (2nded.). Paris: J.B. Ballière.

Gall, F. (1822). Sur les Fonctions du Cerveau et sur Celles de Chacune de ses Partes (Vol. 2). Paris: J.B. Ballière.

Gratiolet, P., & Leuret, F. (1839–1857). Anatomie Comparée du Système Nerveux, Considerée dans ses Rapports avec l’Intelligence (Vol. 2 by Gratioletalone). Paris: J.B. Ballière.

Greenblatt, S.H. (1970). Hughlings Jackson’s first encounter with the work of Paul Broca: The physiological and philosophical background. Bulletin of the History of Medicine, 44 , 555–570.

Harrington, A. (1985). Nineteenth-century ideas on hemisphere differences and “duality of mind.”. Behavioral and Brain Sciences, 8 , 617–660.

Harrington, A. (1986). Models of mind and the double brain: Some historical and contemporary reflections. Cognitive Neuropsychology, 3 , 411–427.

Harrington, A. (1987). Medicine, mind and the double brain . Princeton: Princeton University Press.

Harris, L.J. (1991). Cerebral control for speech in right-handers andleft-handers: An analysis of the views of Paul Broca, his contemporaries, and his successors. Brain and Language, 40 , 1–50.

Harris, L.J. (1993). Broca on cerebral control for speech in right-handers and left-handers: Anote on translation and some further comments. Brain and Language, 45 , 108–120.

Holland, H. (1852). On the brain as adouble organ. In H. Holland (Ed.), Chapters on mental physiology (pp.170–191). London: Longman, Brown, Green & Longmans.

Jackson, J.H. (1864a). Hemiplegia on the right side, with loss of speech. British Medical Journal, 1 , 572–573.

Jackson, J.H. (1864b). Clinical remarks on cases of defects of expression (by words, writing, signs, etc.) in diseases of the nervous system. Lancet, 2 , 604–605.

Jackson, J.H. (1868). Hemispheral coordination. Medical Times and Gazette, 2 , 208–209.

Jackson, J.H. (1872). Case of disease of the brain – left hemiplegia – mental affection. Medical Times and Gazette, 1 , 513–514.

Jackson, J.H. (1874a). On the nature of the duality of the brain. Medical Press and Circular, New Ser., 17 , 19–21

Jackson, J.H. (1874b). Remarks on systematic sensations in epilepsies. British Medical Journal, 1 , 174.

Jackson, J.H. (1876). Case of large cerebral tumour without optic neuritis and with left hemiplegia and imperception. Ophthalmic Hospital Reports, 8 , 434–444.

Joynt, R.J., & Benton, A.L. (1964). The memoir of Marc Dax on aphasia. Neurology, 14 , 851–854.

Lokhorst, G.-J.C. (1985). Hemisphere differences before 1800. Behavioral and Brain Sciences, 8 , 642.

Lokhorst, G.-J.C. (1996). The first theory about hemispheric specialization: Fresh light on an old codex. Journal of the History of Medicine and Allied Sciences, 51 , 293–312.

Lombroso, C. (1903). Left-handedness and left-sidedness. North American Review, 177 , 440–444.

Luys, J.B. (1879). Etudes sur le dédoublement des opérations cérébrales et sur le rôle isolé de chaque hémisphère dans les phénomènes de la pathologie mentale. Bulletin de l’Académie de Médecine, 2nd. Ser., 8 , 516–534, 547–565.

Luys, J. B. (1881). Contribution à l’étude d’une statistique sur les poids des hémisphères cérébraux à l’état normal et à l’état pathologique. Encéphale , 1 , 644–646.

Marro, A., & Lombroso, C. (1883). Ambidestrismo nei pazzi enei criminali. Archivio di Psichiatria, Antropologia Criminale eScienze Penali, 4 , 229–230.

Meynert, T. (1866). Ein Fall von Sprachstörung, anatomisch begründet. Medizinische Jahrbücher (pp.152–189 . Redigiert von C. Braun, A. Duchek, L. Schlager. XII. Band der Zeitschrif der K.K. Gesellschaft der Ärzte in Wien, 22. Lahr.

Neuburger, M. (1981). The historical development of experimental brain and spinal cord physiology before flourens . (Translated and edited with additional material by E. Clarke). Baltimore: Johns Hopkins University Press.

Oppenheimer, J. (1977). Studies of brain asymmetry: Historical perspective. Annals of the New York Academy of Medicine, 299 , 4–17.

Ravoire, J. (1933). Une Page d’Histoire de la Médecine: Le Docteur Marc Dax (de Sommières) et l’Aphasie . Montpellier: Mari-Lavit.

Roe, D., & Finger, S. (1996). Gustave Dax and his fight for recognition: An overlooked chapter in the history of cerebral dominance. Journal of the History of the Neurosciences, 5 , 228–240.

Roques, F. (1869). Sur un cas d’asymétrie de l’encéphale, de la moëlle, du sternum et des ovaires. Bulletins de la Société d’Anthropologie de Paris, Ser. 2, 4 , 727–732.

Schiller, F. (1979). Paul Broca: Founder of French anthropology, explorer of the brain . Berkeley: University of California Press.

Souques, A. (1928). Quelques cases d'anarthie de Pierre Marie: aperçu historique sur la localisation du langage. Revue Neurologique , 2 , 319–368.

Stevenson, R.L. (1886). Strange case of Dr. Jekyll and Mr. Hyde . London: Longmans, Green.

Thurnam, J. (1866). On the weight of the brain, and on the circumstances affecting it. Journal of Mental Science, 12 , 1–43.

Vicq d’Azyr. F. (1805). Oeuvres de Vicq d’Azyr . J.L. Moreau (Ed.),. Paris: L. Duprat-Duverger.

Watson, H. (1836). What is the use of the double brain? The Phrenological Journal and Miscellany, 9 , 608–611.

Wernicke, C. (1874). Der aphasische symptomenkomplex: Eine psychologische Studie auf anatomischer Basis . Breslau: Cohn & Weigert.

Whitaker, H.A., & Etlinger, S.C. (1993). Theodor Meynert’s contribution to classical 19th century aphasia studies. Brain and Language, 45 , 560–571.

Wigan, A.L. (1844a). A new view of insanity: The duality of the mind . London: Longman, Brown, Green & Longmans.

Wigan, A.L. (1844b). Duality of the mind, proved by the structure, functions, and diseases of the brain. Lancet, 1 , 39–41.

Zangwill, O.L., & Wyke, M.A. (1990). Hughlings Jackson on the recognition of places, persons, and objects. In C. Trevarthen (Ed.), Brain circuits and functions of the mind (pp.281–292). Cambridge: Cambridge University Press.

Download references

Author information

Authors and affiliations.

Department of Psychology, Programs in Neuroscience and Philosophy-Neuroscience-Psychology, Washington University, Campus Box 1125, St. Louis, MO, 63130-4899, USA

Stanley Finger

You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Stanley Finger .

Editor information

Editors and affiliations.

Department of Psychology, Fordham University, New York, NY, USA

Robert W. Rieber

Rights and permissions

Reprints and permissions

Copyright information

About this entry

Cite this entry.

Finger, S. (2012). Cerebral Dominance. In: Rieber, R.W. (eds) Encyclopedia of the History of Psychological Theories. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-0463-8_160

Download citation

DOI : https://doi.org/10.1007/978-1-4419-0463-8_160

Publisher Name : Springer, New York, NY

Print ISBN : 978-1-4419-0425-6

Online ISBN : 978-1-4419-0463-8

eBook Packages : Behavioral Science

Share this entry

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

Publish with us

Policies and ethics

Find a journal
Track your research

Recent Blog Articles

Your amazing parathyroid glands

When — and how — should you be screened for colon cancer?

Co-regulation: Helping children and teens navigate big emotions

Dog bites: How to prevent or treat them

Will miscarriage care remain available?

Can AI answer medical questions better than your doctor?

How to stay healthy during a drought

Opill: Is this new birth control pill right for you?

How well do you worry about your health?

Ready to give up the lead vest?

Mind & Mood

Right brain/left brain, right?

An image of a brain with flowers on the right side and wires on the left.

Follow me on Twitter @RobShmerling

If you're like me, you learned that about 90% of people are right-handed and much of the reason is genetic. And that's true, although it remains a mystery why our genetic evolution led to so many more righties than lefties.

But for certain tasks, handedness can be "overcome." For example, right-handed kids learning to play tennis, golf, or baseball can become successful hitting from "the other side." It may be more a matter of how they are taught and what gets reinforced than about a hard-wired preference for one hand or the other.

According to recent research, the idea of people being "left-brained" or "right-brained" may also be less fixed than we'd thought.

Recognize yourself?

According to conventional wisdom, people tend to have a personality, thinking style, or way of doing things that is either right-brained or left-brained.

Those who are right-brained are supposed to be intuitive and creative free thinkers. They are "qualitative," big-picture thinkers who experience the world in terms that are descriptive or subjective. For example, "The skies are gray and menacing; I wonder if it's going to rain?"

Meanwhile, left-brained people tend to be more quantitative and analytical. They pay attention to details and are ruled by logic. Their view of the weather is more likely, "The forecast said there was only a 30% chance of rain, but those cumulonimbus clouds will probably bring thunder as well as rain."

A popular book first published in 1979, Drawing on the Right Side of the Brain , extends this concept. It suggests that regardless of how your brain is wired, getting in touch with your "right brain" will help you see — and draw — things differently.

These notions of "left and right brain-ness" are widespread and widely accepted. But they may also be wrong.

Location matters

There is truth to the idea that some brain functions reside more on one side of the brain than the other. We know this in part from what is lost when a stroke affects a particular part of the brain. For example, it has long been thought that, in most people, control of language resides in the left side of the brain. And there are areas of the right half the brain that control movement of the left arm and leg (and vice versa). Damage to the front part of the brain is linked with reduced motivation, difficulty planning, and impaired creativity. Meanwhile, the back of the brain (the occipital cortex) integrates visual information from the eye. Damage to this area can cause partial or complete blindness. These are just a few examples of how certain parts of the brain appear responsible for specific functions. So, location does matter.

But for more individual personality traits, such as creativity or a tendency toward the rational rather than the intuitive, there has been little or no evidence supporting a residence in one area of the brain. In fact, if you performed a CT scan, MRI scan, or even an autopsy on the brain of a mathematician and compared it to the brain of an artist, it's unlikely you'd find much difference. And if you did the same for 1,000 mathematicians and artists, it's unlikely that any clear pattern of difference in brain structure would emerge.

The right-brain/left brain myth?

So, is the idea of "thinking with the left side of your brain" a myth? Maybe. But, the lack of proof does not prove the opposite. For people living thousands of years ago, an inability to prove the earth was round did not prove the earth was flat!

But, the evidence discounting the left/right brain concept is accumulating. According to a 2013 study from the University of Utah, brain scans demonstrate that activity is similar on both sides of the brain regardless of one's personality.

They looked at the brain scans of more than 1,000 young people between the ages of 7 and 29 and divided different areas of the brain into 7,000 regions to determine whether one side of the brain was more active or connected than the other side. No evidence of "sidedness" was found. The authors concluded that the notion of some people being more left-brained or right-brained is more a figure of speech than an anatomically accurate description.

On the other hand, researchers continue to study brain laterality – that is, which parts (and sides) of the brain are dominant when considering different brain functions such as language skills or facial recognition.

The bottom line

If you've always thought of yourself as a "numbers person" or a creative sort, this area of research doesn't change anything. But it's probably inaccurate to link these traits one side of your brain. We still don't know a lot about what determines individual personality; but it seems unlikely that it's solely the dominance of one side of the brain or the other that matters most.

Image: BlueLela/Getty Images

About the Author

Robert H. Shmerling, MD , Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Disclaimer:

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Free Healthbeat Signup

Get the latest in health news delivered to your inbox!

Thanks for visiting. Don't miss your FREE gift.

The Best Diets for Cognitive Fitness , is yours absolutely FREE when you sign up to receive Health Alerts from Harvard Medical School

Sign up to get tips for living a healthy lifestyle, with ways to fight inflammation and improve cognitive health , plus the latest advances in preventative medicine, diet and exercise , pain relief, blood pressure and cholesterol management, and more.

Health Alerts from Harvard Medical School

Get helpful tips and guidance for everything from fighting inflammation to finding the best diets for weight loss ...from exercises to build a stronger core to advice on treating cataracts . PLUS, the latest news on medical advances and breakthroughs from Harvard Medical School experts.

BONUS! Sign up now and get a FREE copy of the Best Diets for Cognitive Fitness

Stay on top of latest health news from Harvard Medical School.

Plus, get a FREE copy of the Best Diets for Cognitive Fitness .

Work Life is Atlassian’s flagship publication dedicated to unleashing the potential of every team through real-life advice, inspiring stories, and thoughtful perspectives from leaders around the world.

Contributing Writer

Work Futurist

Senior Quantitative Researcher, People Insights

Principal Writer

Left brain vs. right brain: fact or fiction?

We’re busting myths about the brain and sharing ways you can use yours to blow minds at work.

Get stories like this in your inbox

5-second summary

In the 1960s, neuroscience research showed that one side of the brain tends to be more dominant in each person. Since then, many people have categorized themselves as “left-brained” (analytical, methodical, logical) or “right-brained” (artsy, creative, emotional).
Although these labels can make it easier to understand ourselves and each other, they’re limiting and, frankly, not even accurate anymore. Since the original experiments in the 60s, several more studies have busted the left brain vs. right brain myth.
Recent research shows that the human mind is beautifully complex, constantly changing, and made for learning and growth. Each side controls different functions throughout the body, and both sides work together in amazing ways to help us become our best selves.

“I’m an Enneagram 1.”

“ENTJ. You?”

“It’s Sagittarius season!”

“I’m left-brained. Totally Type A.”

If you’ve taken personality tests or looked up your horoscope before, at least one of these probably rings a bell. But even if you haven’t, you’ve surely sparked a conversation with someone over a shared trait, interest, talent, or experience.

And you’re not alone. It’s human nature to put ourselves into categories and try to connect with similar people. For example, at work, the more artsy and creative team members (often stereotyped as “right-brained” people) often hang out together, while the more analytical “left-brained people” (managers, coordinators, analysts, etc.) tend to get along well.

While donning these self-imposed labels can help us navigate the complex world around us and build relationships more easily, this process of “social categorization” can oversimplify our identities, hinder our growth, and even be flat-out wrong — as is the case with the longstanding left brain vs. right brain myth.

🧠 The basics: how the human brain works

The human brain is an incredible organ. So incredible that we could dedicate this whole article to how it works. But since we’re teamwork experts, not neuroscientists, we’ll leave the detailed anatomy lessons to them and give you a super simple overview.

Weighing around three pounds, the brain controls not only how we think, but also how every bit of our body works. Our mind contains about 100 billion neurons and 100 trillion (with a “t!”) connections, which send and receive signals throughout the body via a superhighway of nerves. No matter how far the message has to go, it only takes a split second to get there. (Hence why stepping on a teeny tiny LEGO or stubbing your toe sends an immediate message to your brain to let out a supersized scream 😱)

The brain is divided into two halves: one hemisphere on the right and one on the left. Each hemisphere has four lobes, which each manage a different function – some voluntary, such as tasting and touching, and some involuntary, like breathing and blinking. And each hemisphere controls the opposite side of the body (right hemisphere = left side, left hemisphere = right side).

Although each part of the brain is responsible for different functions, they all work together as a “command center” to control all of our senses, movements, behavior, and survival. By better understanding how our brains work — and how they don’t — we can not just survive , but thrive .

🤔 Myth busting: Is there such a thing as left brain vs. right brain dominance?

There’s a longstanding belief that says one side of the brain is more dominant in each person. This left-brain vs. right-brain dominance theory first emerged in the 1960s when psychobiologist Roger W. Sperry conducted split-brain experiments . He and his counterpart, psychology professor Michael Gazzaniga, were some of the first scientists to investigate hemispheric lateralization, a fancy way of saying that each side of the brain specializes in different jobs or roles.

Sperry and Gazzaniga found that the left hemisphere controls speech, language, and comprehension; recognizes words, letters, and numbers; and does analysis and calculations. This is why people who are more methodical and logical are believed to be “left-brained.” Meanwhile, the right hemisphere controls creativity, perception, and spatial understanding, and recognizes faces, places, and objects – hence why more creative and emotional people are said to be “right-brained.”

Sperry won a Nobel Prize for his split-brain research, and some of it still rings true decades later. Each side of the brain is, indeed, different. Certain parts also control separate functions. And both sides still work together to keep the body running like a well-oiled machine.

However, over time, the left brain vs. right brain dominance theory has proven to be more fiction than fact. In 2013, a team of neuroscientists reviewed Sperry and Gazzaniga’s research, along with new evidence, and debunked several previous findings:

The human brain does not favor one side over the other.
The two sides work differently, but one side is not stronger than the other unless it’s damaged. (Likewise, despite what a bratty sibling or bully may have told you in middle school, neither brain size nor strength correlate to intelligence. Certain areas of the brain simply have stronger neural connections than others, which is what makes each of us better at certain skills – and those connections skills can be strengthened with practice.)
We do not only use one side of our brain at a time. Both sides work in concert. For example, our left brain may do the heavy lifting with calculations, but our right brain helps with estimates and numerical comparisons.

So, while we can still thank Sperry for helping us understand how certain parts of the mind work, this myth about dominance has officially been busted.

🤯 3 brainy facts that will blow your mind and benefit your work

Not only has Sperry’s theory been debunked as overly simplistic, but subsequent research also shows that the brain is even more amazing than we once thought. It’s constantly adapting to change, reorganizing, and learning based on physical interactions and life experiences.

This bodes especially well for everyone in the world of work. No matter how old we are or what stage we’re at in our careers, science shows it’s always possible to grow and improve.

Curious what your left and right brain are actually capable of? Here are three fun facts about the mind that you can use to your advantage at work.

Learning changes the structure of your brain

9 neuroplasticity exercises to boost productivity

During your first day on the job, you probably felt overwhelmed and maybe even out of your league. There are so many new people to meet, new environments to get used to, and new concepts to learn. But after a few weeks or months, you start to get the hang of it and feel more comfortable.

That’s because your brain sends messages along the body’s superhighway of nerves over and over, forming new connections and making foreign things feel familiar. It’s how we learn any new skill and absorb information.

In fact, the literal structure of our brain changes every time we learn something new, have a new thought, or make a new memory. Even when our brain suffers major damage, it can completely reprogram itself through a process called neuroplasticity . (Wild, right?) This is how people who have experienced physical injuries or mental trauma can heal – and how we can keep learning and growing as professionals.

Put it to work

It’s easy to get comfortable on the job, but our minds crave information . To satiate your brain’s desire for learning and keep yourself sharp, try setting aside dedicated time for training and exploration. It could be something as simple as blocking off one hour every other week to read the latest industry news or brush up on a new skill, going to a conference or event a few times each year, or a more formal initiative like participating in a secondment (job rotation) program or professional development course .

Boredom can be beneficial

The surprising, science-backed value of boredom at work

Ever notice some of the best ideas strike when you’re in the shower, commuting, or laying in bed? It’s not a coincidence – it’s science!

John Eastwood, a psychologist and co-author of Out of My Skull: The Psychology of Boredom , explains that boredom can be a huge driver of innovation. When the mind is quiet, creativity kicks in to fill the empty space.

A 2013 study also showed that small amounts of boredom help prime our brains to do convergent thinking, like solving a problem. Another study the following year highlighted that we also need creativity for divergent thinking, like brainstorming. So either way, a little boredom can go a long way.

Consider ways to make space in your schedule for an “anti-power hour” each week: one hour where you’re not expected to produce anything. During this time, you can let your mind wander, get away from the computer and go do something that inspires you, or give yourself the time to do some open-ended, divergent thinking exercises about a topic you haven’t had a chance to tackle.

The best ideas happen when we contemplate, then collaborate

Research shows that collaborative problem-solving leads to better outcomes , as well as personal growth, greater job satisfaction, and less stress. However, a 2018 study out of Harvard Business School suggests that individual brainstorming followed by collaboration can lead to superior solutions.

In the study, three groups of participants were asked to solve traveling salesman problems . The first group worked individually, the second exchanged notes after every round of brainstorming, and the third collaborated after every three rounds.

The results were fascinating. The first group thought of many different solutions, but quality varied. The second group came up with better solutions since they got to work together throughout the process, but they ended up influencing each other and prematurely settling on one idea. The third group performed best. They each got to explore and develop their own thoughts, then come together to build on each other’s ideas – the best of both worlds.

put it to work

When your team is trying to solve a problem or come up with a new concept, start brainstorming individually, then share ideas with the group and refine them together. Techniques like Six Thinking Hats can also be effective for tackling tough decisions by having each person look at the problem with a different “hat” on, or through a different lens.

🪴“When you stop learning, you stop growing.”

Personality tests and labels can make it easier to connect with each other and help us better understand how we interact with our teammates and the world around us. However, it’s best to treat them as fun, not facts, and resist the urge to put ourselves in the purely “right-brained” or “left-brained” box – or any category, for that matter.

Even if someone tends to think more logically or creatively, we contain multitudes. Both sides of our brains are constantly working together, learning, and evolving into the next best version. Let’s bust out of the left brain vs. right brain box and develop a growth mindset to give our craniums what they crave. As Albert Einstein once said, “Never stop learning, for when you stop learning, you stop growing.”

Advice, stories, and expertise about work life today.

Table of Contents
Random Entry
Chronological
Editorial Information
About the SEP
Editorial Board
How to Cite the SEP
Special Characters
Advanced Tools
Support the SEP
PDFs for SEP Friends
Make a Donation
SEPIA for Libraries
Entry Contents

Bibliography

Academic tools.

Friends PDF Preview
Author and Citation Info
Back to Top

Critical Thinking

Critical thinking is a widely accepted educational goal. Its definition is contested, but the competing definitions can be understood as differing conceptions of the same basic concept: careful thinking directed to a goal. Conceptions differ with respect to the scope of such thinking, the type of goal, the criteria and norms for thinking carefully, and the thinking components on which they focus. Its adoption as an educational goal has been recommended on the basis of respect for students’ autonomy and preparing students for success in life and for democratic citizenship. “Critical thinkers” have the dispositions and abilities that lead them to think critically when appropriate. The abilities can be identified directly; the dispositions indirectly, by considering what factors contribute to or impede exercise of the abilities. Standardized tests have been developed to assess the degree to which a person possesses such dispositions and abilities. Educational intervention has been shown experimentally to improve them, particularly when it includes dialogue, anchored instruction, and mentoring. Controversies have arisen over the generalizability of critical thinking across domains, over alleged bias in critical thinking theories and instruction, and over the relationship of critical thinking to other types of thinking.

2.1 Dewey’s Three Main Examples

2.2 dewey’s other examples, 2.3 further examples, 2.4 non-examples, 3. the definition of critical thinking, 4. its value, 5. the process of thinking critically, 6. components of the process, 7. contributory dispositions and abilities, 8.1 initiating dispositions, 8.2 internal dispositions, 9. critical thinking abilities, 10. required knowledge, 11. educational methods, 12.1 the generalizability of critical thinking, 12.2 bias in critical thinking theory and pedagogy, 12.3 relationship of critical thinking to other types of thinking, other internet resources, related entries.

Use of the term ‘critical thinking’ to describe an educational goal goes back to the American philosopher John Dewey (1910), who more commonly called it ‘reflective thinking’. He defined it as

active, persistent and careful consideration of any belief or supposed form of knowledge in the light of the grounds that support it, and the further conclusions to which it tends. (Dewey 1910: 6; 1933: 9)

and identified a habit of such consideration with a scientific attitude of mind. His lengthy quotations of Francis Bacon, John Locke, and John Stuart Mill indicate that he was not the first person to propose development of a scientific attitude of mind as an educational goal.

In the 1930s, many of the schools that participated in the Eight-Year Study of the Progressive Education Association (Aikin 1942) adopted critical thinking as an educational goal, for whose achievement the study’s Evaluation Staff developed tests (Smith, Tyler, & Evaluation Staff 1942). Glaser (1941) showed experimentally that it was possible to improve the critical thinking of high school students. Bloom’s influential taxonomy of cognitive educational objectives (Bloom et al. 1956) incorporated critical thinking abilities. Ennis (1962) proposed 12 aspects of critical thinking as a basis for research on the teaching and evaluation of critical thinking ability.

Since 1980, an annual international conference in California on critical thinking and educational reform has attracted tens of thousands of educators from all levels of education and from many parts of the world. Also since 1980, the state university system in California has required all undergraduate students to take a critical thinking course. Since 1983, the Association for Informal Logic and Critical Thinking has sponsored sessions in conjunction with the divisional meetings of the American Philosophical Association (APA). In 1987, the APA’s Committee on Pre-College Philosophy commissioned a consensus statement on critical thinking for purposes of educational assessment and instruction (Facione 1990a). Researchers have developed standardized tests of critical thinking abilities and dispositions; for details, see the Supplement on Assessment . Educational jurisdictions around the world now include critical thinking in guidelines for curriculum and assessment.

For details on this history, see the Supplement on History .

2. Examples and Non-Examples

Before considering the definition of critical thinking, it will be helpful to have in mind some examples of critical thinking, as well as some examples of kinds of thinking that would apparently not count as critical thinking.

Dewey (1910: 68–71; 1933: 91–94) takes as paradigms of reflective thinking three class papers of students in which they describe their thinking. The examples range from the everyday to the scientific.

Transit : “The other day, when I was down town on 16th Street, a clock caught my eye. I saw that the hands pointed to 12:20. This suggested that I had an engagement at 124th Street, at one o’clock. I reasoned that as it had taken me an hour to come down on a surface car, I should probably be twenty minutes late if I returned the same way. I might save twenty minutes by a subway express. But was there a station near? If not, I might lose more than twenty minutes in looking for one. Then I thought of the elevated, and I saw there was such a line within two blocks. But where was the station? If it were several blocks above or below the street I was on, I should lose time instead of gaining it. My mind went back to the subway express as quicker than the elevated; furthermore, I remembered that it went nearer than the elevated to the part of 124th Street I wished to reach, so that time would be saved at the end of the journey. I concluded in favor of the subway, and reached my destination by one o’clock.” (Dewey 1910: 68–69; 1933: 91–92)

Ferryboat : “Projecting nearly horizontally from the upper deck of the ferryboat on which I daily cross the river is a long white pole, having a gilded ball at its tip. It suggested a flagpole when I first saw it; its color, shape, and gilded ball agreed with this idea, and these reasons seemed to justify me in this belief. But soon difficulties presented themselves. The pole was nearly horizontal, an unusual position for a flagpole; in the next place, there was no pulley, ring, or cord by which to attach a flag; finally, there were elsewhere on the boat two vertical staffs from which flags were occasionally flown. It seemed probable that the pole was not there for flag-flying.

“I then tried to imagine all possible purposes of the pole, and to consider for which of these it was best suited: (a) Possibly it was an ornament. But as all the ferryboats and even the tugboats carried poles, this hypothesis was rejected. (b) Possibly it was the terminal of a wireless telegraph. But the same considerations made this improbable. Besides, the more natural place for such a terminal would be the highest part of the boat, on top of the pilot house. (c) Its purpose might be to point out the direction in which the boat is moving.

“In support of this conclusion, I discovered that the pole was lower than the pilot house, so that the steersman could easily see it. Moreover, the tip was enough higher than the base, so that, from the pilot’s position, it must appear to project far out in front of the boat. Moreover, the pilot being near the front of the boat, he would need some such guide as to its direction. Tugboats would also need poles for such a purpose. This hypothesis was so much more probable than the others that I accepted it. I formed the conclusion that the pole was set up for the purpose of showing the pilot the direction in which the boat pointed, to enable him to steer correctly.” (Dewey 1910: 69–70; 1933: 92–93)

Bubbles : “In washing tumblers in hot soapsuds and placing them mouth downward on a plate, bubbles appeared on the outside of the mouth of the tumblers and then went inside. Why? The presence of bubbles suggests air, which I note must come from inside the tumbler. I see that the soapy water on the plate prevents escape of the air save as it may be caught in bubbles. But why should air leave the tumbler? There was no substance entering to force it out. It must have expanded. It expands by increase of heat, or by decrease of pressure, or both. Could the air have become heated after the tumbler was taken from the hot suds? Clearly not the air that was already entangled in the water. If heated air was the cause, cold air must have entered in transferring the tumblers from the suds to the plate. I test to see if this supposition is true by taking several more tumblers out. Some I shake so as to make sure of entrapping cold air in them. Some I take out holding mouth downward in order to prevent cold air from entering. Bubbles appear on the outside of every one of the former and on none of the latter. I must be right in my inference. Air from the outside must have been expanded by the heat of the tumbler, which explains the appearance of the bubbles on the outside. But why do they then go inside? Cold contracts. The tumbler cooled and also the air inside it. Tension was removed, and hence bubbles appeared inside. To be sure of this, I test by placing a cup of ice on the tumbler while the bubbles are still forming outside. They soon reverse” (Dewey 1910: 70–71; 1933: 93–94).

Dewey (1910, 1933) sprinkles his book with other examples of critical thinking. We will refer to the following.

Weather : A man on a walk notices that it has suddenly become cool, thinks that it is probably going to rain, looks up and sees a dark cloud obscuring the sun, and quickens his steps (1910: 6–10; 1933: 9–13).

Disorder : A man finds his rooms on his return to them in disorder with his belongings thrown about, thinks at first of burglary as an explanation, then thinks of mischievous children as being an alternative explanation, then looks to see whether valuables are missing, and discovers that they are (1910: 82–83; 1933: 166–168).

Typhoid : A physician diagnosing a patient whose conspicuous symptoms suggest typhoid avoids drawing a conclusion until more data are gathered by questioning the patient and by making tests (1910: 85–86; 1933: 170).

Blur : A moving blur catches our eye in the distance, we ask ourselves whether it is a cloud of whirling dust or a tree moving its branches or a man signaling to us, we think of other traits that should be found on each of those possibilities, and we look and see if those traits are found (1910: 102, 108; 1933: 121, 133).

Suction pump : In thinking about the suction pump, the scientist first notes that it will draw water only to a maximum height of 33 feet at sea level and to a lesser maximum height at higher elevations, selects for attention the differing atmospheric pressure at these elevations, sets up experiments in which the air is removed from a vessel containing water (when suction no longer works) and in which the weight of air at various levels is calculated, compares the results of reasoning about the height to which a given weight of air will allow a suction pump to raise water with the observed maximum height at different elevations, and finally assimilates the suction pump to such apparently different phenomena as the siphon and the rising of a balloon (1910: 150–153; 1933: 195–198).

Diamond : A passenger in a car driving in a diamond lane reserved for vehicles with at least one passenger notices that the diamond marks on the pavement are far apart in some places and close together in others. Why? The driver suggests that the reason may be that the diamond marks are not needed where there is a solid double line separating the diamond lane from the adjoining lane, but are needed when there is a dotted single line permitting crossing into the diamond lane. Further observation confirms that the diamonds are close together when a dotted line separates the diamond lane from its neighbour, but otherwise far apart.

Rash : A woman suddenly develops a very itchy red rash on her throat and upper chest. She recently noticed a mark on the back of her right hand, but was not sure whether the mark was a rash or a scrape. She lies down in bed and thinks about what might be causing the rash and what to do about it. About two weeks before, she began taking blood pressure medication that contained a sulfa drug, and the pharmacist had warned her, in view of a previous allergic reaction to a medication containing a sulfa drug, to be on the alert for an allergic reaction; however, she had been taking the medication for two weeks with no such effect. The day before, she began using a new cream on her neck and upper chest; against the new cream as the cause was mark on the back of her hand, which had not been exposed to the cream. She began taking probiotics about a month before. She also recently started new eye drops, but she supposed that manufacturers of eye drops would be careful not to include allergy-causing components in the medication. The rash might be a heat rash, since she recently was sweating profusely from her upper body. Since she is about to go away on a short vacation, where she would not have access to her usual physician, she decides to keep taking the probiotics and using the new eye drops but to discontinue the blood pressure medication and to switch back to the old cream for her neck and upper chest. She forms a plan to consult her regular physician on her return about the blood pressure medication.

Candidate : Although Dewey included no examples of thinking directed at appraising the arguments of others, such thinking has come to be considered a kind of critical thinking. We find an example of such thinking in the performance task on the Collegiate Learning Assessment (CLA+), which its sponsoring organization describes as

a performance-based assessment that provides a measure of an institution’s contribution to the development of critical-thinking and written communication skills of its students. (Council for Aid to Education 2017)

A sample task posted on its website requires the test-taker to write a report for public distribution evaluating a fictional candidate’s policy proposals and their supporting arguments, using supplied background documents, with a recommendation on whether to endorse the candidate.

Immediate acceptance of an idea that suggests itself as a solution to a problem (e.g., a possible explanation of an event or phenomenon, an action that seems likely to produce a desired result) is “uncritical thinking, the minimum of reflection” (Dewey 1910: 13). On-going suspension of judgment in the light of doubt about a possible solution is not critical thinking (Dewey 1910: 108). Critique driven by a dogmatically held political or religious ideology is not critical thinking; thus Paulo Freire (1968 [1970]) is using the term (e.g., at 1970: 71, 81, 100, 146) in a more politically freighted sense that includes not only reflection but also revolutionary action against oppression. Derivation of a conclusion from given data using an algorithm is not critical thinking.

What is critical thinking? There are many definitions. Ennis (2016) lists 14 philosophically oriented scholarly definitions and three dictionary definitions. Following Rawls (1971), who distinguished his conception of justice from a utilitarian conception but regarded them as rival conceptions of the same concept, Ennis maintains that the 17 definitions are different conceptions of the same concept. Rawls articulated the shared concept of justice as

a characteristic set of principles for assigning basic rights and duties and for determining… the proper distribution of the benefits and burdens of social cooperation. (Rawls 1971: 5)

Bailin et al. (1999b) claim that, if one considers what sorts of thinking an educator would take not to be critical thinking and what sorts to be critical thinking, one can conclude that educators typically understand critical thinking to have at least three features.

It is done for the purpose of making up one’s mind about what to believe or do.
The person engaging in the thinking is trying to fulfill standards of adequacy and accuracy appropriate to the thinking.
The thinking fulfills the relevant standards to some threshold level.

One could sum up the core concept that involves these three features by saying that critical thinking is careful goal-directed thinking. This core concept seems to apply to all the examples of critical thinking described in the previous section. As for the non-examples, their exclusion depends on construing careful thinking as excluding jumping immediately to conclusions, suspending judgment no matter how strong the evidence, reasoning from an unquestioned ideological or religious perspective, and routinely using an algorithm to answer a question.

If the core of critical thinking is careful goal-directed thinking, conceptions of it can vary according to its presumed scope, its presumed goal, one’s criteria and threshold for being careful, and the thinking component on which one focuses. As to its scope, some conceptions (e.g., Dewey 1910, 1933) restrict it to constructive thinking on the basis of one’s own observations and experiments, others (e.g., Ennis 1962; Fisher & Scriven 1997; Johnson 1992) to appraisal of the products of such thinking. Ennis (1991) and Bailin et al. (1999b) take it to cover both construction and appraisal. As to its goal, some conceptions restrict it to forming a judgment (Dewey 1910, 1933; Lipman 1987; Facione 1990a). Others allow for actions as well as beliefs as the end point of a process of critical thinking (Ennis 1991; Bailin et al. 1999b). As to the criteria and threshold for being careful, definitions vary in the term used to indicate that critical thinking satisfies certain norms: “intellectually disciplined” (Scriven & Paul 1987), “reasonable” (Ennis 1991), “skillful” (Lipman 1987), “skilled” (Fisher & Scriven 1997), “careful” (Bailin & Battersby 2009). Some definitions specify these norms, referring variously to “consideration of any belief or supposed form of knowledge in the light of the grounds that support it and the further conclusions to which it tends” (Dewey 1910, 1933); “the methods of logical inquiry and reasoning” (Glaser 1941); “conceptualizing, applying, analyzing, synthesizing, and/or evaluating information gathered from, or generated by, observation, experience, reflection, reasoning, or communication” (Scriven & Paul 1987); the requirement that “it is sensitive to context, relies on criteria, and is self-correcting” (Lipman 1987); “evidential, conceptual, methodological, criteriological, or contextual considerations” (Facione 1990a); and “plus-minus considerations of the product in terms of appropriate standards (or criteria)” (Johnson 1992). Stanovich and Stanovich (2010) propose to ground the concept of critical thinking in the concept of rationality, which they understand as combining epistemic rationality (fitting one’s beliefs to the world) and instrumental rationality (optimizing goal fulfillment); a critical thinker, in their view, is someone with “a propensity to override suboptimal responses from the autonomous mind” (2010: 227). These variant specifications of norms for critical thinking are not necessarily incompatible with one another, and in any case presuppose the core notion of thinking carefully. As to the thinking component singled out, some definitions focus on suspension of judgment during the thinking (Dewey 1910; McPeck 1981), others on inquiry while judgment is suspended (Bailin & Battersby 2009, 2021), others on the resulting judgment (Facione 1990a), and still others on responsiveness to reasons (Siegel 1988). Kuhn (2019) takes critical thinking to be more a dialogic practice of advancing and responding to arguments than an individual ability.

In educational contexts, a definition of critical thinking is a “programmatic definition” (Scheffler 1960: 19). It expresses a practical program for achieving an educational goal. For this purpose, a one-sentence formulaic definition is much less useful than articulation of a critical thinking process, with criteria and standards for the kinds of thinking that the process may involve. The real educational goal is recognition, adoption and implementation by students of those criteria and standards. That adoption and implementation in turn consists in acquiring the knowledge, abilities and dispositions of a critical thinker.

Conceptions of critical thinking generally do not include moral integrity as part of the concept. Dewey, for example, took critical thinking to be the ultimate intellectual goal of education, but distinguished it from the development of social cooperation among school children, which he took to be the central moral goal. Ennis (1996, 2011) added to his previous list of critical thinking dispositions a group of dispositions to care about the dignity and worth of every person, which he described as a “correlative” (1996) disposition without which critical thinking would be less valuable and perhaps harmful. An educational program that aimed at developing critical thinking but not the correlative disposition to care about the dignity and worth of every person, he asserted, “would be deficient and perhaps dangerous” (Ennis 1996: 172).

Dewey thought that education for reflective thinking would be of value to both the individual and society; recognition in educational practice of the kinship to the scientific attitude of children’s native curiosity, fertile imagination and love of experimental inquiry “would make for individual happiness and the reduction of social waste” (Dewey 1910: iii). Schools participating in the Eight-Year Study took development of the habit of reflective thinking and skill in solving problems as a means to leading young people to understand, appreciate and live the democratic way of life characteristic of the United States (Aikin 1942: 17–18, 81). Harvey Siegel (1988: 55–61) has offered four considerations in support of adopting critical thinking as an educational ideal. (1) Respect for persons requires that schools and teachers honour students’ demands for reasons and explanations, deal with students honestly, and recognize the need to confront students’ independent judgment; these requirements concern the manner in which teachers treat students. (2) Education has the task of preparing children to be successful adults, a task that requires development of their self-sufficiency. (3) Education should initiate children into the rational traditions in such fields as history, science and mathematics. (4) Education should prepare children to become democratic citizens, which requires reasoned procedures and critical talents and attitudes. To supplement these considerations, Siegel (1988: 62–90) responds to two objections: the ideology objection that adoption of any educational ideal requires a prior ideological commitment and the indoctrination objection that cultivation of critical thinking cannot escape being a form of indoctrination.

Despite the diversity of our 11 examples, one can recognize a common pattern. Dewey analyzed it as consisting of five phases:

suggestions , in which the mind leaps forward to a possible solution;
an intellectualization of the difficulty or perplexity into a problem to be solved, a question for which the answer must be sought;
the use of one suggestion after another as a leading idea, or hypothesis , to initiate and guide observation and other operations in collection of factual material;
the mental elaboration of the idea or supposition as an idea or supposition ( reasoning , in the sense on which reasoning is a part, not the whole, of inference); and
testing the hypothesis by overt or imaginative action. (Dewey 1933: 106–107; italics in original)

The process of reflective thinking consisting of these phases would be preceded by a perplexed, troubled or confused situation and followed by a cleared-up, unified, resolved situation (Dewey 1933: 106). The term ‘phases’ replaced the term ‘steps’ (Dewey 1910: 72), thus removing the earlier suggestion of an invariant sequence. Variants of the above analysis appeared in (Dewey 1916: 177) and (Dewey 1938: 101–119).

The variant formulations indicate the difficulty of giving a single logical analysis of such a varied process. The process of critical thinking may have a spiral pattern, with the problem being redefined in the light of obstacles to solving it as originally formulated. For example, the person in Transit might have concluded that getting to the appointment at the scheduled time was impossible and have reformulated the problem as that of rescheduling the appointment for a mutually convenient time. Further, defining a problem does not always follow after or lead immediately to an idea of a suggested solution. Nor should it do so, as Dewey himself recognized in describing the physician in Typhoid as avoiding any strong preference for this or that conclusion before getting further information (Dewey 1910: 85; 1933: 170). People with a hypothesis in mind, even one to which they have a very weak commitment, have a so-called “confirmation bias” (Nickerson 1998): they are likely to pay attention to evidence that confirms the hypothesis and to ignore evidence that counts against it or for some competing hypothesis. Detectives, intelligence agencies, and investigators of airplane accidents are well advised to gather relevant evidence systematically and to postpone even tentative adoption of an explanatory hypothesis until the collected evidence rules out with the appropriate degree of certainty all but one explanation. Dewey’s analysis of the critical thinking process can be faulted as well for requiring acceptance or rejection of a possible solution to a defined problem, with no allowance for deciding in the light of the available evidence to suspend judgment. Further, given the great variety of kinds of problems for which reflection is appropriate, there is likely to be variation in its component events. Perhaps the best way to conceptualize the critical thinking process is as a checklist whose component events can occur in a variety of orders, selectively, and more than once. These component events might include (1) noticing a difficulty, (2) defining the problem, (3) dividing the problem into manageable sub-problems, (4) formulating a variety of possible solutions to the problem or sub-problem, (5) determining what evidence is relevant to deciding among possible solutions to the problem or sub-problem, (6) devising a plan of systematic observation or experiment that will uncover the relevant evidence, (7) carrying out the plan of systematic observation or experimentation, (8) noting the results of the systematic observation or experiment, (9) gathering relevant testimony and information from others, (10) judging the credibility of testimony and information gathered from others, (11) drawing conclusions from gathered evidence and accepted testimony, and (12) accepting a solution that the evidence adequately supports (cf. Hitchcock 2017: 485).

Checklist conceptions of the process of critical thinking are open to the objection that they are too mechanical and procedural to fit the multi-dimensional and emotionally charged issues for which critical thinking is urgently needed (Paul 1984). For such issues, a more dialectical process is advocated, in which competing relevant world views are identified, their implications explored, and some sort of creative synthesis attempted.

If one considers the critical thinking process illustrated by the 11 examples, one can identify distinct kinds of mental acts and mental states that form part of it. To distinguish, label and briefly characterize these components is a useful preliminary to identifying abilities, skills, dispositions, attitudes, habits and the like that contribute causally to thinking critically. Identifying such abilities and habits is in turn a useful preliminary to setting educational goals. Setting the goals is in its turn a useful preliminary to designing strategies for helping learners to achieve the goals and to designing ways of measuring the extent to which learners have done so. Such measures provide both feedback to learners on their achievement and a basis for experimental research on the effectiveness of various strategies for educating people to think critically. Let us begin, then, by distinguishing the kinds of mental acts and mental events that can occur in a critical thinking process.

Observing : One notices something in one’s immediate environment (sudden cooling of temperature in Weather , bubbles forming outside a glass and then going inside in Bubbles , a moving blur in the distance in Blur , a rash in Rash ). Or one notes the results of an experiment or systematic observation (valuables missing in Disorder , no suction without air pressure in Suction pump )
Feeling : One feels puzzled or uncertain about something (how to get to an appointment on time in Transit , why the diamonds vary in spacing in Diamond ). One wants to resolve this perplexity. One feels satisfaction once one has worked out an answer (to take the subway express in Transit , diamonds closer when needed as a warning in Diamond ).
Wondering : One formulates a question to be addressed (why bubbles form outside a tumbler taken from hot water in Bubbles , how suction pumps work in Suction pump , what caused the rash in Rash ).
Imagining : One thinks of possible answers (bus or subway or elevated in Transit , flagpole or ornament or wireless communication aid or direction indicator in Ferryboat , allergic reaction or heat rash in Rash ).
Inferring : One works out what would be the case if a possible answer were assumed (valuables missing if there has been a burglary in Disorder , earlier start to the rash if it is an allergic reaction to a sulfa drug in Rash ). Or one draws a conclusion once sufficient relevant evidence is gathered (take the subway in Transit , burglary in Disorder , discontinue blood pressure medication and new cream in Rash ).
Knowledge : One uses stored knowledge of the subject-matter to generate possible answers or to infer what would be expected on the assumption of a particular answer (knowledge of a city’s public transit system in Transit , of the requirements for a flagpole in Ferryboat , of Boyle’s law in Bubbles , of allergic reactions in Rash ).
Experimenting : One designs and carries out an experiment or a systematic observation to find out whether the results deduced from a possible answer will occur (looking at the location of the flagpole in relation to the pilot’s position in Ferryboat , putting an ice cube on top of a tumbler taken from hot water in Bubbles , measuring the height to which a suction pump will draw water at different elevations in Suction pump , noticing the spacing of diamonds when movement to or from a diamond lane is allowed in Diamond ).
Consulting : One finds a source of information, gets the information from the source, and makes a judgment on whether to accept it. None of our 11 examples include searching for sources of information. In this respect they are unrepresentative, since most people nowadays have almost instant access to information relevant to answering any question, including many of those illustrated by the examples. However, Candidate includes the activities of extracting information from sources and evaluating its credibility.
Identifying and analyzing arguments : One notices an argument and works out its structure and content as a preliminary to evaluating its strength. This activity is central to Candidate . It is an important part of a critical thinking process in which one surveys arguments for various positions on an issue.
Judging : One makes a judgment on the basis of accumulated evidence and reasoning, such as the judgment in Ferryboat that the purpose of the pole is to provide direction to the pilot.
Deciding : One makes a decision on what to do or on what policy to adopt, as in the decision in Transit to take the subway.

By definition, a person who does something voluntarily is both willing and able to do that thing at that time. Both the willingness and the ability contribute causally to the person’s action, in the sense that the voluntary action would not occur if either (or both) of these were lacking. For example, suppose that one is standing with one’s arms at one’s sides and one voluntarily lifts one’s right arm to an extended horizontal position. One would not do so if one were unable to lift one’s arm, if for example one’s right side was paralyzed as the result of a stroke. Nor would one do so if one were unwilling to lift one’s arm, if for example one were participating in a street demonstration at which a white supremacist was urging the crowd to lift their right arm in a Nazi salute and one were unwilling to express support in this way for the racist Nazi ideology. The same analysis applies to a voluntary mental process of thinking critically. It requires both willingness and ability to think critically, including willingness and ability to perform each of the mental acts that compose the process and to coordinate those acts in a sequence that is directed at resolving the initiating perplexity.

Consider willingness first. We can identify causal contributors to willingness to think critically by considering factors that would cause a person who was able to think critically about an issue nevertheless not to do so (Hamby 2014). For each factor, the opposite condition thus contributes causally to willingness to think critically on a particular occasion. For example, people who habitually jump to conclusions without considering alternatives will not think critically about issues that arise, even if they have the required abilities. The contrary condition of willingness to suspend judgment is thus a causal contributor to thinking critically.

Now consider ability. In contrast to the ability to move one’s arm, which can be completely absent because a stroke has left the arm paralyzed, the ability to think critically is a developed ability, whose absence is not a complete absence of ability to think but absence of ability to think well. We can identify the ability to think well directly, in terms of the norms and standards for good thinking. In general, to be able do well the thinking activities that can be components of a critical thinking process, one needs to know the concepts and principles that characterize their good performance, to recognize in particular cases that the concepts and principles apply, and to apply them. The knowledge, recognition and application may be procedural rather than declarative. It may be domain-specific rather than widely applicable, and in either case may need subject-matter knowledge, sometimes of a deep kind.

Reflections of the sort illustrated by the previous two paragraphs have led scholars to identify the knowledge, abilities and dispositions of a “critical thinker”, i.e., someone who thinks critically whenever it is appropriate to do so. We turn now to these three types of causal contributors to thinking critically. We start with dispositions, since arguably these are the most powerful contributors to being a critical thinker, can be fostered at an early stage of a child’s development, and are susceptible to general improvement (Glaser 1941: 175)

8. Critical Thinking Dispositions

Educational researchers use the term ‘dispositions’ broadly for the habits of mind and attitudes that contribute causally to being a critical thinker. Some writers (e.g., Paul & Elder 2006; Hamby 2014; Bailin & Battersby 2016a) propose to use the term ‘virtues’ for this dimension of a critical thinker. The virtues in question, although they are virtues of character, concern the person’s ways of thinking rather than the person’s ways of behaving towards others. They are not moral virtues but intellectual virtues, of the sort articulated by Zagzebski (1996) and discussed by Turri, Alfano, and Greco (2017).

On a realistic conception, thinking dispositions or intellectual virtues are real properties of thinkers. They are general tendencies, propensities, or inclinations to think in particular ways in particular circumstances, and can be genuinely explanatory (Siegel 1999). Sceptics argue that there is no evidence for a specific mental basis for the habits of mind that contribute to thinking critically, and that it is pedagogically misleading to posit such a basis (Bailin et al. 1999a). Whatever their status, critical thinking dispositions need motivation for their initial formation in a child—motivation that may be external or internal. As children develop, the force of habit will gradually become important in sustaining the disposition (Nieto & Valenzuela 2012). Mere force of habit, however, is unlikely to sustain critical thinking dispositions. Critical thinkers must value and enjoy using their knowledge and abilities to think things through for themselves. They must be committed to, and lovers of, inquiry.

A person may have a critical thinking disposition with respect to only some kinds of issues. For example, one could be open-minded about scientific issues but not about religious issues. Similarly, one could be confident in one’s ability to reason about the theological implications of the existence of evil in the world but not in one’s ability to reason about the best design for a guided ballistic missile.

Facione (1990a: 25) divides “affective dispositions” of critical thinking into approaches to life and living in general and approaches to specific issues, questions or problems. Adapting this distinction, one can usefully divide critical thinking dispositions into initiating dispositions (those that contribute causally to starting to think critically about an issue) and internal dispositions (those that contribute causally to doing a good job of thinking critically once one has started). The two categories are not mutually exclusive. For example, open-mindedness, in the sense of willingness to consider alternative points of view to one’s own, is both an initiating and an internal disposition.

Using the strategy of considering factors that would block people with the ability to think critically from doing so, we can identify as initiating dispositions for thinking critically attentiveness, a habit of inquiry, self-confidence, courage, open-mindedness, willingness to suspend judgment, trust in reason, wanting evidence for one’s beliefs, and seeking the truth. We consider briefly what each of these dispositions amounts to, in each case citing sources that acknowledge them.

Attentiveness : One will not think critically if one fails to recognize an issue that needs to be thought through. For example, the pedestrian in Weather would not have looked up if he had not noticed that the air was suddenly cooler. To be a critical thinker, then, one needs to be habitually attentive to one’s surroundings, noticing not only what one senses but also sources of perplexity in messages received and in one’s own beliefs and attitudes (Facione 1990a: 25; Facione, Facione, & Giancarlo 2001).
Habit of inquiry : Inquiry is effortful, and one needs an internal push to engage in it. For example, the student in Bubbles could easily have stopped at idle wondering about the cause of the bubbles rather than reasoning to a hypothesis, then designing and executing an experiment to test it. Thus willingness to think critically needs mental energy and initiative. What can supply that energy? Love of inquiry, or perhaps just a habit of inquiry. Hamby (2015) has argued that willingness to inquire is the central critical thinking virtue, one that encompasses all the others. It is recognized as a critical thinking disposition by Dewey (1910: 29; 1933: 35), Glaser (1941: 5), Ennis (1987: 12; 1991: 8), Facione (1990a: 25), Bailin et al. (1999b: 294), Halpern (1998: 452), and Facione, Facione, & Giancarlo (2001).
Self-confidence : Lack of confidence in one’s abilities can block critical thinking. For example, if the woman in Rash lacked confidence in her ability to figure things out for herself, she might just have assumed that the rash on her chest was the allergic reaction to her medication against which the pharmacist had warned her. Thus willingness to think critically requires confidence in one’s ability to inquire (Facione 1990a: 25; Facione, Facione, & Giancarlo 2001).
Courage : Fear of thinking for oneself can stop one from doing it. Thus willingness to think critically requires intellectual courage (Paul & Elder 2006: 16).
Open-mindedness : A dogmatic attitude will impede thinking critically. For example, a person who adheres rigidly to a “pro-choice” position on the issue of the legal status of induced abortion is likely to be unwilling to consider seriously the issue of when in its development an unborn child acquires a moral right to life. Thus willingness to think critically requires open-mindedness, in the sense of a willingness to examine questions to which one already accepts an answer but which further evidence or reasoning might cause one to answer differently (Dewey 1933; Facione 1990a; Ennis 1991; Bailin et al. 1999b; Halpern 1998, Facione, Facione, & Giancarlo 2001). Paul (1981) emphasizes open-mindedness about alternative world-views, and recommends a dialectical approach to integrating such views as central to what he calls “strong sense” critical thinking. In three studies, Haran, Ritov, & Mellers (2013) found that actively open-minded thinking, including “the tendency to weigh new evidence against a favored belief, to spend sufficient time on a problem before giving up, and to consider carefully the opinions of others in forming one’s own”, led study participants to acquire information and thus to make accurate estimations.
Willingness to suspend judgment : Premature closure on an initial solution will block critical thinking. Thus willingness to think critically requires a willingness to suspend judgment while alternatives are explored (Facione 1990a; Ennis 1991; Halpern 1998).
Trust in reason : Since distrust in the processes of reasoned inquiry will dissuade one from engaging in it, trust in them is an initiating critical thinking disposition (Facione 1990a, 25; Bailin et al. 1999b: 294; Facione, Facione, & Giancarlo 2001; Paul & Elder 2006). In reaction to an allegedly exclusive emphasis on reason in critical thinking theory and pedagogy, Thayer-Bacon (2000) argues that intuition, imagination, and emotion have important roles to play in an adequate conception of critical thinking that she calls “constructive thinking”. From her point of view, critical thinking requires trust not only in reason but also in intuition, imagination, and emotion.
Seeking the truth : If one does not care about the truth but is content to stick with one’s initial bias on an issue, then one will not think critically about it. Seeking the truth is thus an initiating critical thinking disposition (Bailin et al. 1999b: 294; Facione, Facione, & Giancarlo 2001). A disposition to seek the truth is implicit in more specific critical thinking dispositions, such as trying to be well-informed, considering seriously points of view other than one’s own, looking for alternatives, suspending judgment when the evidence is insufficient, and adopting a position when the evidence supporting it is sufficient.

Some of the initiating dispositions, such as open-mindedness and willingness to suspend judgment, are also internal critical thinking dispositions, in the sense of mental habits or attitudes that contribute causally to doing a good job of critical thinking once one starts the process. But there are many other internal critical thinking dispositions. Some of them are parasitic on one’s conception of good thinking. For example, it is constitutive of good thinking about an issue to formulate the issue clearly and to maintain focus on it. For this purpose, one needs not only the corresponding ability but also the corresponding disposition. Ennis (1991: 8) describes it as the disposition “to determine and maintain focus on the conclusion or question”, Facione (1990a: 25) as “clarity in stating the question or concern”. Other internal dispositions are motivators to continue or adjust the critical thinking process, such as willingness to persist in a complex task and willingness to abandon nonproductive strategies in an attempt to self-correct (Halpern 1998: 452). For a list of identified internal critical thinking dispositions, see the Supplement on Internal Critical Thinking Dispositions .

Some theorists postulate skills, i.e., acquired abilities, as operative in critical thinking. It is not obvious, however, that a good mental act is the exercise of a generic acquired skill. Inferring an expected time of arrival, as in Transit , has some generic components but also uses non-generic subject-matter knowledge. Bailin et al. (1999a) argue against viewing critical thinking skills as generic and discrete, on the ground that skilled performance at a critical thinking task cannot be separated from knowledge of concepts and from domain-specific principles of good thinking. Talk of skills, they concede, is unproblematic if it means merely that a person with critical thinking skills is capable of intelligent performance.

Despite such scepticism, theorists of critical thinking have listed as general contributors to critical thinking what they variously call abilities (Glaser 1941; Ennis 1962, 1991), skills (Facione 1990a; Halpern 1998) or competencies (Fisher & Scriven 1997). Amalgamating these lists would produce a confusing and chaotic cornucopia of more than 50 possible educational objectives, with only partial overlap among them. It makes sense instead to try to understand the reasons for the multiplicity and diversity, and to make a selection according to one’s own reasons for singling out abilities to be developed in a critical thinking curriculum. Two reasons for diversity among lists of critical thinking abilities are the underlying conception of critical thinking and the envisaged educational level. Appraisal-only conceptions, for example, involve a different suite of abilities than constructive-only conceptions. Some lists, such as those in (Glaser 1941), are put forward as educational objectives for secondary school students, whereas others are proposed as objectives for college students (e.g., Facione 1990a).

The abilities described in the remaining paragraphs of this section emerge from reflection on the general abilities needed to do well the thinking activities identified in section 6 as components of the critical thinking process described in section 5 . The derivation of each collection of abilities is accompanied by citation of sources that list such abilities and of standardized tests that claim to test them.

Observational abilities : Careful and accurate observation sometimes requires specialist expertise and practice, as in the case of observing birds and observing accident scenes. However, there are general abilities of noticing what one’s senses are picking up from one’s environment and of being able to articulate clearly and accurately to oneself and others what one has observed. It helps in exercising them to be able to recognize and take into account factors that make one’s observation less trustworthy, such as prior framing of the situation, inadequate time, deficient senses, poor observation conditions, and the like. It helps as well to be skilled at taking steps to make one’s observation more trustworthy, such as moving closer to get a better look, measuring something three times and taking the average, and checking what one thinks one is observing with someone else who is in a good position to observe it. It also helps to be skilled at recognizing respects in which one’s report of one’s observation involves inference rather than direct observation, so that one can then consider whether the inference is justified. These abilities come into play as well when one thinks about whether and with what degree of confidence to accept an observation report, for example in the study of history or in a criminal investigation or in assessing news reports. Observational abilities show up in some lists of critical thinking abilities (Ennis 1962: 90; Facione 1990a: 16; Ennis 1991: 9). There are items testing a person’s ability to judge the credibility of observation reports in the Cornell Critical Thinking Tests, Levels X and Z (Ennis & Millman 1971; Ennis, Millman, & Tomko 1985, 2005). Norris and King (1983, 1985, 1990a, 1990b) is a test of ability to appraise observation reports.

Emotional abilities : The emotions that drive a critical thinking process are perplexity or puzzlement, a wish to resolve it, and satisfaction at achieving the desired resolution. Children experience these emotions at an early age, without being trained to do so. Education that takes critical thinking as a goal needs only to channel these emotions and to make sure not to stifle them. Collaborative critical thinking benefits from ability to recognize one’s own and others’ emotional commitments and reactions.

Questioning abilities : A critical thinking process needs transformation of an inchoate sense of perplexity into a clear question. Formulating a question well requires not building in questionable assumptions, not prejudging the issue, and using language that in context is unambiguous and precise enough (Ennis 1962: 97; 1991: 9).

Imaginative abilities : Thinking directed at finding the correct causal explanation of a general phenomenon or particular event requires an ability to imagine possible explanations. Thinking about what policy or plan of action to adopt requires generation of options and consideration of possible consequences of each option. Domain knowledge is required for such creative activity, but a general ability to imagine alternatives is helpful and can be nurtured so as to become easier, quicker, more extensive, and deeper (Dewey 1910: 34–39; 1933: 40–47). Facione (1990a) and Halpern (1998) include the ability to imagine alternatives as a critical thinking ability.

Inferential abilities : The ability to draw conclusions from given information, and to recognize with what degree of certainty one’s own or others’ conclusions follow, is universally recognized as a general critical thinking ability. All 11 examples in section 2 of this article include inferences, some from hypotheses or options (as in Transit , Ferryboat and Disorder ), others from something observed (as in Weather and Rash ). None of these inferences is formally valid. Rather, they are licensed by general, sometimes qualified substantive rules of inference (Toulmin 1958) that rest on domain knowledge—that a bus trip takes about the same time in each direction, that the terminal of a wireless telegraph would be located on the highest possible place, that sudden cooling is often followed by rain, that an allergic reaction to a sulfa drug generally shows up soon after one starts taking it. It is a matter of controversy to what extent the specialized ability to deduce conclusions from premisses using formal rules of inference is needed for critical thinking. Dewey (1933) locates logical forms in setting out the products of reflection rather than in the process of reflection. Ennis (1981a), on the other hand, maintains that a liberally-educated person should have the following abilities: to translate natural-language statements into statements using the standard logical operators, to use appropriately the language of necessary and sufficient conditions, to deal with argument forms and arguments containing symbols, to determine whether in virtue of an argument’s form its conclusion follows necessarily from its premisses, to reason with logically complex propositions, and to apply the rules and procedures of deductive logic. Inferential abilities are recognized as critical thinking abilities by Glaser (1941: 6), Facione (1990a: 9), Ennis (1991: 9), Fisher & Scriven (1997: 99, 111), and Halpern (1998: 452). Items testing inferential abilities constitute two of the five subtests of the Watson Glaser Critical Thinking Appraisal (Watson & Glaser 1980a, 1980b, 1994), two of the four sections in the Cornell Critical Thinking Test Level X (Ennis & Millman 1971; Ennis, Millman, & Tomko 1985, 2005), three of the seven sections in the Cornell Critical Thinking Test Level Z (Ennis & Millman 1971; Ennis, Millman, & Tomko 1985, 2005), 11 of the 34 items on Forms A and B of the California Critical Thinking Skills Test (Facione 1990b, 1992), and a high but variable proportion of the 25 selected-response questions in the Collegiate Learning Assessment (Council for Aid to Education 2017).

Experimenting abilities : Knowing how to design and execute an experiment is important not just in scientific research but also in everyday life, as in Rash . Dewey devoted a whole chapter of his How We Think (1910: 145–156; 1933: 190–202) to the superiority of experimentation over observation in advancing knowledge. Experimenting abilities come into play at one remove in appraising reports of scientific studies. Skill in designing and executing experiments includes the acknowledged abilities to appraise evidence (Glaser 1941: 6), to carry out experiments and to apply appropriate statistical inference techniques (Facione 1990a: 9), to judge inductions to an explanatory hypothesis (Ennis 1991: 9), and to recognize the need for an adequately large sample size (Halpern 1998). The Cornell Critical Thinking Test Level Z (Ennis & Millman 1971; Ennis, Millman, & Tomko 1985, 2005) includes four items (out of 52) on experimental design. The Collegiate Learning Assessment (Council for Aid to Education 2017) makes room for appraisal of study design in both its performance task and its selected-response questions.

Consulting abilities : Skill at consulting sources of information comes into play when one seeks information to help resolve a problem, as in Candidate . Ability to find and appraise information includes ability to gather and marshal pertinent information (Glaser 1941: 6), to judge whether a statement made by an alleged authority is acceptable (Ennis 1962: 84), to plan a search for desired information (Facione 1990a: 9), and to judge the credibility of a source (Ennis 1991: 9). Ability to judge the credibility of statements is tested by 24 items (out of 76) in the Cornell Critical Thinking Test Level X (Ennis & Millman 1971; Ennis, Millman, & Tomko 1985, 2005) and by four items (out of 52) in the Cornell Critical Thinking Test Level Z (Ennis & Millman 1971; Ennis, Millman, & Tomko 1985, 2005). The College Learning Assessment’s performance task requires evaluation of whether information in documents is credible or unreliable (Council for Aid to Education 2017).

Argument analysis abilities : The ability to identify and analyze arguments contributes to the process of surveying arguments on an issue in order to form one’s own reasoned judgment, as in Candidate . The ability to detect and analyze arguments is recognized as a critical thinking skill by Facione (1990a: 7–8), Ennis (1991: 9) and Halpern (1998). Five items (out of 34) on the California Critical Thinking Skills Test (Facione 1990b, 1992) test skill at argument analysis. The College Learning Assessment (Council for Aid to Education 2017) incorporates argument analysis in its selected-response tests of critical reading and evaluation and of critiquing an argument.

Judging skills and deciding skills : Skill at judging and deciding is skill at recognizing what judgment or decision the available evidence and argument supports, and with what degree of confidence. It is thus a component of the inferential skills already discussed.

Lists and tests of critical thinking abilities often include two more abilities: identifying assumptions and constructing and evaluating definitions.

In addition to dispositions and abilities, critical thinking needs knowledge: of critical thinking concepts, of critical thinking principles, and of the subject-matter of the thinking.

We can derive a short list of concepts whose understanding contributes to critical thinking from the critical thinking abilities described in the preceding section. Observational abilities require an understanding of the difference between observation and inference. Questioning abilities require an understanding of the concepts of ambiguity and vagueness. Inferential abilities require an understanding of the difference between conclusive and defeasible inference (traditionally, between deduction and induction), as well as of the difference between necessary and sufficient conditions. Experimenting abilities require an understanding of the concepts of hypothesis, null hypothesis, assumption and prediction, as well as of the concept of statistical significance and of its difference from importance. They also require an understanding of the difference between an experiment and an observational study, and in particular of the difference between a randomized controlled trial, a prospective correlational study and a retrospective (case-control) study. Argument analysis abilities require an understanding of the concepts of argument, premiss, assumption, conclusion and counter-consideration. Additional critical thinking concepts are proposed by Bailin et al. (1999b: 293), Fisher & Scriven (1997: 105–106), Black (2012), and Blair (2021).

According to Glaser (1941: 25), ability to think critically requires knowledge of the methods of logical inquiry and reasoning. If we review the list of abilities in the preceding section, however, we can see that some of them can be acquired and exercised merely through practice, possibly guided in an educational setting, followed by feedback. Searching intelligently for a causal explanation of some phenomenon or event requires that one consider a full range of possible causal contributors, but it seems more important that one implements this principle in one’s practice than that one is able to articulate it. What is important is “operational knowledge” of the standards and principles of good thinking (Bailin et al. 1999b: 291–293). But the development of such critical thinking abilities as designing an experiment or constructing an operational definition can benefit from learning their underlying theory. Further, explicit knowledge of quirks of human thinking seems useful as a cautionary guide. Human memory is not just fallible about details, as people learn from their own experiences of misremembering, but is so malleable that a detailed, clear and vivid recollection of an event can be a total fabrication (Loftus 2017). People seek or interpret evidence in ways that are partial to their existing beliefs and expectations, often unconscious of their “confirmation bias” (Nickerson 1998). Not only are people subject to this and other cognitive biases (Kahneman 2011), of which they are typically unaware, but it may be counter-productive for one to make oneself aware of them and try consciously to counteract them or to counteract social biases such as racial or sexual stereotypes (Kenyon & Beaulac 2014). It is helpful to be aware of these facts and of the superior effectiveness of blocking the operation of biases—for example, by making an immediate record of one’s observations, refraining from forming a preliminary explanatory hypothesis, blind refereeing, double-blind randomized trials, and blind grading of students’ work. It is also helpful to be aware of the prevalence of “noise” (unwanted unsystematic variability of judgments), of how to detect noise (through a noise audit), and of how to reduce noise: make accuracy the goal, think statistically, break a process of arriving at a judgment into independent tasks, resist premature intuitions, in a group get independent judgments first, favour comparative judgments and scales (Kahneman, Sibony, & Sunstein 2021). It is helpful as well to be aware of the concept of “bounded rationality” in decision-making and of the related distinction between “satisficing” and optimizing (Simon 1956; Gigerenzer 2001).

Critical thinking about an issue requires substantive knowledge of the domain to which the issue belongs. Critical thinking abilities are not a magic elixir that can be applied to any issue whatever by somebody who has no knowledge of the facts relevant to exploring that issue. For example, the student in Bubbles needed to know that gases do not penetrate solid objects like a glass, that air expands when heated, that the volume of an enclosed gas varies directly with its temperature and inversely with its pressure, and that hot objects will spontaneously cool down to the ambient temperature of their surroundings unless kept hot by insulation or a source of heat. Critical thinkers thus need a rich fund of subject-matter knowledge relevant to the variety of situations they encounter. This fact is recognized in the inclusion among critical thinking dispositions of a concern to become and remain generally well informed.

Experimental educational interventions, with control groups, have shown that education can improve critical thinking skills and dispositions, as measured by standardized tests. For information about these tests, see the Supplement on Assessment .

What educational methods are most effective at developing the dispositions, abilities and knowledge of a critical thinker? In a comprehensive meta-analysis of experimental and quasi-experimental studies of strategies for teaching students to think critically, Abrami et al. (2015) found that dialogue, anchored instruction, and mentoring each increased the effectiveness of the educational intervention, and that they were most effective when combined. They also found that in these studies a combination of separate instruction in critical thinking with subject-matter instruction in which students are encouraged to think critically was more effective than either by itself. However, the difference was not statistically significant; that is, it might have arisen by chance.

Most of these studies lack the longitudinal follow-up required to determine whether the observed differential improvements in critical thinking abilities or dispositions continue over time, for example until high school or college graduation. For details on studies of methods of developing critical thinking skills and dispositions, see the Supplement on Educational Methods .

12. Controversies

Scholars have denied the generalizability of critical thinking abilities across subject domains, have alleged bias in critical thinking theory and pedagogy, and have investigated the relationship of critical thinking to other kinds of thinking.

McPeck (1981) attacked the thinking skills movement of the 1970s, including the critical thinking movement. He argued that there are no general thinking skills, since thinking is always thinking about some subject-matter. It is futile, he claimed, for schools and colleges to teach thinking as if it were a separate subject. Rather, teachers should lead their pupils to become autonomous thinkers by teaching school subjects in a way that brings out their cognitive structure and that encourages and rewards discussion and argument. As some of his critics (e.g., Paul 1985; Siegel 1985) pointed out, McPeck’s central argument needs elaboration, since it has obvious counter-examples in writing and speaking, for which (up to a certain level of complexity) there are teachable general abilities even though they are always about some subject-matter. To make his argument convincing, McPeck needs to explain how thinking differs from writing and speaking in a way that does not permit useful abstraction of its components from the subject-matters with which it deals. He has not done so. Nevertheless, his position that the dispositions and abilities of a critical thinker are best developed in the context of subject-matter instruction is shared by many theorists of critical thinking, including Dewey (1910, 1933), Glaser (1941), Passmore (1980), Weinstein (1990), Bailin et al. (1999b), and Willingham (2019).

McPeck’s challenge prompted reflection on the extent to which critical thinking is subject-specific. McPeck argued for a strong subject-specificity thesis, according to which it is a conceptual truth that all critical thinking abilities are specific to a subject. (He did not however extend his subject-specificity thesis to critical thinking dispositions. In particular, he took the disposition to suspend judgment in situations of cognitive dissonance to be a general disposition.) Conceptual subject-specificity is subject to obvious counter-examples, such as the general ability to recognize confusion of necessary and sufficient conditions. A more modest thesis, also endorsed by McPeck, is epistemological subject-specificity, according to which the norms of good thinking vary from one field to another. Epistemological subject-specificity clearly holds to a certain extent; for example, the principles in accordance with which one solves a differential equation are quite different from the principles in accordance with which one determines whether a painting is a genuine Picasso. But the thesis suffers, as Ennis (1989) points out, from vagueness of the concept of a field or subject and from the obvious existence of inter-field principles, however broadly the concept of a field is construed. For example, the principles of hypothetico-deductive reasoning hold for all the varied fields in which such reasoning occurs. A third kind of subject-specificity is empirical subject-specificity, according to which as a matter of empirically observable fact a person with the abilities and dispositions of a critical thinker in one area of investigation will not necessarily have them in another area of investigation.

The thesis of empirical subject-specificity raises the general problem of transfer. If critical thinking abilities and dispositions have to be developed independently in each school subject, how are they of any use in dealing with the problems of everyday life and the political and social issues of contemporary society, most of which do not fit into the framework of a traditional school subject? Proponents of empirical subject-specificity tend to argue that transfer is more likely to occur if there is critical thinking instruction in a variety of domains, with explicit attention to dispositions and abilities that cut across domains. But evidence for this claim is scanty. There is a need for well-designed empirical studies that investigate the conditions that make transfer more likely.

It is common ground in debates about the generality or subject-specificity of critical thinking dispositions and abilities that critical thinking about any topic requires background knowledge about the topic. For example, the most sophisticated understanding of the principles of hypothetico-deductive reasoning is of no help unless accompanied by some knowledge of what might be plausible explanations of some phenomenon under investigation.

Critics have objected to bias in the theory, pedagogy and practice of critical thinking. Commentators (e.g., Alston 1995; Ennis 1998) have noted that anyone who takes a position has a bias in the neutral sense of being inclined in one direction rather than others. The critics, however, are objecting to bias in the pejorative sense of an unjustified favoring of certain ways of knowing over others, frequently alleging that the unjustly favoured ways are those of a dominant sex or culture (Bailin 1995). These ways favour:

reinforcement of egocentric and sociocentric biases over dialectical engagement with opposing world-views (Paul 1981, 1984; Warren 1998)
distancing from the object of inquiry over closeness to it (Martin 1992; Thayer-Bacon 1992)
indifference to the situation of others over care for them (Martin 1992)
orientation to thought over orientation to action (Martin 1992)
being reasonable over caring to understand people’s ideas (Thayer-Bacon 1993)
being neutral and objective over being embodied and situated (Thayer-Bacon 1995a)
doubting over believing (Thayer-Bacon 1995b)
reason over emotion, imagination and intuition (Thayer-Bacon 2000)
solitary thinking over collaborative thinking (Thayer-Bacon 2000)
written and spoken assignments over other forms of expression (Alston 2001)
attention to written and spoken communications over attention to human problems (Alston 2001)
winning debates in the public sphere over making and understanding meaning (Alston 2001)

A common thread in this smorgasbord of accusations is dissatisfaction with focusing on the logical analysis and evaluation of reasoning and arguments. While these authors acknowledge that such analysis and evaluation is part of critical thinking and should be part of its conceptualization and pedagogy, they insist that it is only a part. Paul (1981), for example, bemoans the tendency of atomistic teaching of methods of analyzing and evaluating arguments to turn students into more able sophists, adept at finding fault with positions and arguments with which they disagree but even more entrenched in the egocentric and sociocentric biases with which they began. Martin (1992) and Thayer-Bacon (1992) cite with approval the self-reported intimacy with their subject-matter of leading researchers in biology and medicine, an intimacy that conflicts with the distancing allegedly recommended in standard conceptions and pedagogy of critical thinking. Thayer-Bacon (2000) contrasts the embodied and socially embedded learning of her elementary school students in a Montessori school, who used their imagination, intuition and emotions as well as their reason, with conceptions of critical thinking as

thinking that is used to critique arguments, offer justifications, and make judgments about what are the good reasons, or the right answers. (Thayer-Bacon 2000: 127–128)

Alston (2001) reports that her students in a women’s studies class were able to see the flaws in the Cinderella myth that pervades much romantic fiction but in their own romantic relationships still acted as if all failures were the woman’s fault and still accepted the notions of love at first sight and living happily ever after. Students, she writes, should

be able to connect their intellectual critique to a more affective, somatic, and ethical account of making risky choices that have sexist, racist, classist, familial, sexual, or other consequences for themselves and those both near and far… critical thinking that reads arguments, texts, or practices merely on the surface without connections to feeling/desiring/doing or action lacks an ethical depth that should infuse the difference between mere cognitive activity and something we want to call critical thinking. (Alston 2001: 34)

Some critics portray such biases as unfair to women. Thayer-Bacon (1992), for example, has charged modern critical thinking theory with being sexist, on the ground that it separates the self from the object and causes one to lose touch with one’s inner voice, and thus stigmatizes women, who (she asserts) link self to object and listen to their inner voice. Her charge does not imply that women as a group are on average less able than men to analyze and evaluate arguments. Facione (1990c) found no difference by sex in performance on his California Critical Thinking Skills Test. Kuhn (1991: 280–281) found no difference by sex in either the disposition or the competence to engage in argumentative thinking.

The critics propose a variety of remedies for the biases that they allege. In general, they do not propose to eliminate or downplay critical thinking as an educational goal. Rather, they propose to conceptualize critical thinking differently and to change its pedagogy accordingly. Their pedagogical proposals arise logically from their objections. They can be summarized as follows:

Focus on argument networks with dialectical exchanges reflecting contesting points of view rather than on atomic arguments, so as to develop “strong sense” critical thinking that transcends egocentric and sociocentric biases (Paul 1981, 1984).
Foster closeness to the subject-matter and feeling connected to others in order to inform a humane democracy (Martin 1992).
Develop “constructive thinking” as a social activity in a community of physically embodied and socially embedded inquirers with personal voices who value not only reason but also imagination, intuition and emotion (Thayer-Bacon 2000).
In developing critical thinking in school subjects, treat as important neither skills nor dispositions but opening worlds of meaning (Alston 2001).
Attend to the development of critical thinking dispositions as well as skills, and adopt the “critical pedagogy” practised and advocated by Freire (1968 [1970]) and hooks (1994) (Dalgleish, Girard, & Davies 2017).

A common thread in these proposals is treatment of critical thinking as a social, interactive, personally engaged activity like that of a quilting bee or a barn-raising (Thayer-Bacon 2000) rather than as an individual, solitary, distanced activity symbolized by Rodin’s The Thinker . One can get a vivid description of education with the former type of goal from the writings of bell hooks (1994, 2010). Critical thinking for her is open-minded dialectical exchange across opposing standpoints and from multiple perspectives, a conception similar to Paul’s “strong sense” critical thinking (Paul 1981). She abandons the structure of domination in the traditional classroom. In an introductory course on black women writers, for example, she assigns students to write an autobiographical paragraph about an early racial memory, then to read it aloud as the others listen, thus affirming the uniqueness and value of each voice and creating a communal awareness of the diversity of the group’s experiences (hooks 1994: 84). Her “engaged pedagogy” is thus similar to the “freedom under guidance” implemented in John Dewey’s Laboratory School of Chicago in the late 1890s and early 1900s. It incorporates the dialogue, anchored instruction, and mentoring that Abrami (2015) found to be most effective in improving critical thinking skills and dispositions.

What is the relationship of critical thinking to problem solving, decision-making, higher-order thinking, creative thinking, and other recognized types of thinking? One’s answer to this question obviously depends on how one defines the terms used in the question. If critical thinking is conceived broadly to cover any careful thinking about any topic for any purpose, then problem solving and decision making will be kinds of critical thinking, if they are done carefully. Historically, ‘critical thinking’ and ‘problem solving’ were two names for the same thing. If critical thinking is conceived more narrowly as consisting solely of appraisal of intellectual products, then it will be disjoint with problem solving and decision making, which are constructive.

Bloom’s taxonomy of educational objectives used the phrase “intellectual abilities and skills” for what had been labeled “critical thinking” by some, “reflective thinking” by Dewey and others, and “problem solving” by still others (Bloom et al. 1956: 38). Thus, the so-called “higher-order thinking skills” at the taxonomy’s top levels of analysis, synthesis and evaluation are just critical thinking skills, although they do not come with general criteria for their assessment (Ennis 1981b). The revised version of Bloom’s taxonomy (Anderson et al. 2001) likewise treats critical thinking as cutting across those types of cognitive process that involve more than remembering (Anderson et al. 2001: 269–270). For details, see the Supplement on History .

As to creative thinking, it overlaps with critical thinking (Bailin 1987, 1988). Thinking about the explanation of some phenomenon or event, as in Ferryboat , requires creative imagination in constructing plausible explanatory hypotheses. Likewise, thinking about a policy question, as in Candidate , requires creativity in coming up with options. Conversely, creativity in any field needs to be balanced by critical appraisal of the draft painting or novel or mathematical theory.

Abrami, Philip C., Robert M. Bernard, Eugene Borokhovski, David I. Waddington, C. Anne Wade, and Tonje Person, 2015, “Strategies for Teaching Students to Think Critically: A Meta-analysis”, Review of Educational Research , 85(2): 275–314. doi:10.3102/0034654314551063
Aikin, Wilford M., 1942, The Story of the Eight-year Study, with Conclusions and Recommendations , Volume I of Adventure in American Education , New York and London: Harper & Brothers. [ Aikin 1942 available online ]
Alston, Kal, 1995, “Begging the Question: Is Critical Thinking Biased?”, Educational Theory , 45(2): 225–233. doi:10.1111/j.1741-5446.1995.00225.x
–––, 2001, “Re/Thinking Critical Thinking: The Seductions of Everyday Life”, Studies in Philosophy and Education , 20(1): 27–40. doi:10.1023/A:1005247128053
American Educational Research Association, 2014, Standards for Educational and Psychological Testing / American Educational Research Association, American Psychological Association, National Council on Measurement in Education , Washington, DC: American Educational Research Association.
Anderson, Lorin W., David R. Krathwohl, Peter W. Airiasian, Kathleen A. Cruikshank, Richard E. Mayer, Paul R. Pintrich, James Raths, and Merlin C. Wittrock, 2001, A Taxonomy for Learning, Teaching and Assessing: A Revision of Bloom’s Taxonomy of Educational Objectives , New York: Longman, complete edition.
Bailin, Sharon, 1987, “Critical and Creative Thinking”, Informal Logic , 9(1): 23–30. [ Bailin 1987 available online ]
–––, 1988, Achieving Extraordinary Ends: An Essay on Creativity , Dordrecht: Kluwer. doi:10.1007/978-94-009-2780-3
–––, 1995, “Is Critical Thinking Biased? Clarifications and Implications”, Educational Theory , 45(2): 191–197. doi:10.1111/j.1741-5446.1995.00191.x
Bailin, Sharon and Mark Battersby, 2009, “Inquiry: A Dialectical Approach to Teaching Critical Thinking”, in Juho Ritola (ed.), Argument Cultures: Proceedings of OSSA 09 , CD-ROM (pp. 1–10), Windsor, ON: OSSA. [ Bailin & Battersby 2009 available online ]
–––, 2016a, “Fostering the Virtues of Inquiry”, Topoi , 35(2): 367–374. doi:10.1007/s11245-015-9307-6
–––, 2016b, Reason in the Balance: An Inquiry Approach to Critical Thinking , Indianapolis: Hackett, 2nd edition.
–––, 2021, “Inquiry: Teaching for Reasoned Judgment”, in Daniel Fasko, Jr. and Frank Fair (eds.), Critical Thinking and Reasoning: Theory, Development, Instruction, and Assessment , Leiden: Brill, pp. 31–46. doi: 10.1163/9789004444591_003
Bailin, Sharon, Roland Case, Jerrold R. Coombs, and Leroi B. Daniels, 1999a, “Common Misconceptions of Critical Thinking”, Journal of Curriculum Studies , 31(3): 269–283. doi:10.1080/002202799183124
–––, 1999b, “Conceptualizing Critical Thinking”, Journal of Curriculum Studies , 31(3): 285–302. doi:10.1080/002202799183133
Blair, J. Anthony, 2021, Studies in Critical Thinking , Windsor, ON: Windsor Studies in Argumentation, 2nd edition. [Available online at https://windsor.scholarsportal.info/omp/index.php/wsia/catalog/book/106]
Berman, Alan M., Seth J. Schwartz, William M. Kurtines, and Steven L. Berman, 2001, “The Process of Exploration in Identity Formation: The Role of Style and Competence”, Journal of Adolescence , 24(4): 513–528. doi:10.1006/jado.2001.0386
Black, Beth (ed.), 2012, An A to Z of Critical Thinking , London: Continuum International Publishing Group.
Bloom, Benjamin Samuel, Max D. Engelhart, Edward J. Furst, Walter H. Hill, and David R. Krathwohl, 1956, Taxonomy of Educational Objectives. Handbook I: Cognitive Domain , New York: David McKay.
Boardman, Frank, Nancy M. Cavender, and Howard Kahane, 2018, Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life , Boston: Cengage, 13th edition.
Browne, M. Neil and Stuart M. Keeley, 2018, Asking the Right Questions: A Guide to Critical Thinking , Hoboken, NJ: Pearson, 12th edition.
Center for Assessment & Improvement of Learning, 2017, Critical Thinking Assessment Test , Cookeville, TN: Tennessee Technological University.
Cleghorn, Paul. 2021. “Critical Thinking in the Elementary School: Practical Guidance for Building a Culture of Thinking”, in Daniel Fasko, Jr. and Frank Fair (eds.), Critical Thinking and Reasoning: Theory, Development, Instruction, and Assessmen t, Leiden: Brill, pp. 150–167. doi: 10.1163/9789004444591_010
Cohen, Jacob, 1988, Statistical Power Analysis for the Behavioral Sciences , Hillsdale, NJ: Lawrence Erlbaum Associates, 2nd edition.
College Board, 1983, Academic Preparation for College. What Students Need to Know and Be Able to Do , New York: College Entrance Examination Board, ERIC document ED232517.
Commission on the Relation of School and College of the Progressive Education Association, 1943, Thirty Schools Tell Their Story , Volume V of Adventure in American Education , New York and London: Harper & Brothers.
Council for Aid to Education, 2017, CLA+ Student Guide . Available at http://cae.org/images/uploads/pdf/CLA_Student_Guide_Institution.pdf ; last accessed 2022 07 16.
Dalgleish, Adam, Patrick Girard, and Maree Davies, 2017, “Critical Thinking, Bias and Feminist Philosophy: Building a Better Framework through Collaboration”, Informal Logic , 37(4): 351–369. [ Dalgleish et al. available online ]
Dewey, John, 1910, How We Think , Boston: D.C. Heath. [ Dewey 1910 available online ]
–––, 1916, Democracy and Education: An Introduction to the Philosophy of Education , New York: Macmillan.
–––, 1933, How We Think: A Restatement of the Relation of Reflective Thinking to the Educative Process , Lexington, MA: D.C. Heath.
–––, 1936, “The Theory of the Chicago Experiment”, Appendix II of Mayhew & Edwards 1936: 463–477.
–––, 1938, Logic: The Theory of Inquiry , New York: Henry Holt and Company.
Dominguez, Caroline (coord.), 2018a, A European Collection of the Critical Thinking Skills and Dispositions Needed in Different Professional Fields for the 21st Century , Vila Real, Portugal: UTAD. Available at http://bit.ly/CRITHINKEDUO1 ; last accessed 2022 07 16.
––– (coord.), 2018b, A European Review on Critical Thinking Educational Practices in Higher Education Institutions , Vila Real: UTAD. Available at http://bit.ly/CRITHINKEDUO2 ; last accessed 2022 07 16.
––– (coord.), 2018c, The CRITHINKEDU European Course on Critical Thinking Education for University Teachers: From Conception to Delivery , Vila Real: UTAD. Available at http:/bit.ly/CRITHINKEDU03; last accessed 2022 07 16.
Dominguez Caroline and Rita Payan-Carreira (eds.), 2019, Promoting Critical Thinking in European Higher Education Institutions: Towards an Educational Protocol , Vila Real: UTAD. Available at http:/bit.ly/CRITHINKEDU04; last accessed 2022 07 16.
Ennis, Robert H., 1958, “An Appraisal of the Watson-Glaser Critical Thinking Appraisal”, The Journal of Educational Research , 52(4): 155–158. doi:10.1080/00220671.1958.10882558
–––, 1962, “A Concept of Critical Thinking: A Proposed Basis for Research on the Teaching and Evaluation of Critical Thinking Ability”, Harvard Educational Review , 32(1): 81–111.
–––, 1981a, “A Conception of Deductive Logical Competence”, Teaching Philosophy , 4(3/4): 337–385. doi:10.5840/teachphil198143/429
–––, 1981b, “Eight Fallacies in Bloom’s Taxonomy”, in C. J. B. Macmillan (ed.), Philosophy of Education 1980: Proceedings of the Thirty-seventh Annual Meeting of the Philosophy of Education Society , Bloomington, IL: Philosophy of Education Society, pp. 269–273.
–––, 1984, “Problems in Testing Informal Logic, Critical Thinking, Reasoning Ability”, Informal Logic , 6(1): 3–9. [ Ennis 1984 available online ]
–––, 1987, “A Taxonomy of Critical Thinking Dispositions and Abilities”, in Joan Boykoff Baron and Robert J. Sternberg (eds.), Teaching Thinking Skills: Theory and Practice , New York: W. H. Freeman, pp. 9–26.
–––, 1989, “Critical Thinking and Subject Specificity: Clarification and Needed Research”, Educational Researcher , 18(3): 4–10. doi:10.3102/0013189X018003004
–––, 1991, “Critical Thinking: A Streamlined Conception”, Teaching Philosophy , 14(1): 5–24. doi:10.5840/teachphil19911412
–––, 1996, “Critical Thinking Dispositions: Their Nature and Assessability”, Informal Logic , 18(2–3): 165–182. [ Ennis 1996 available online ]
–––, 1998, “Is Critical Thinking Culturally Biased?”, Teaching Philosophy , 21(1): 15–33. doi:10.5840/teachphil19982113
–––, 2011, “Critical Thinking: Reflection and Perspective Part I”, Inquiry: Critical Thinking across the Disciplines , 26(1): 4–18. doi:10.5840/inquiryctnews20112613
–––, 2013, “Critical Thinking across the Curriculum: The Wisdom CTAC Program”, Inquiry: Critical Thinking across the Disciplines , 28(2): 25–45. doi:10.5840/inquiryct20132828
–––, 2016, “Definition: A Three-Dimensional Analysis with Bearing on Key Concepts”, in Patrick Bondy and Laura Benacquista (eds.), Argumentation, Objectivity, and Bias: Proceedings of the 11th International Conference of the Ontario Society for the Study of Argumentation (OSSA), 18–21 May 2016 , Windsor, ON: OSSA, pp. 1–19. Available at http://scholar.uwindsor.ca/ossaarchive/OSSA11/papersandcommentaries/105 ; last accessed 2022 07 16.
–––, 2018, “Critical Thinking Across the Curriculum: A Vision”, Topoi , 37(1): 165–184. doi:10.1007/s11245-016-9401-4
Ennis, Robert H., and Jason Millman, 1971, Manual for Cornell Critical Thinking Test, Level X, and Cornell Critical Thinking Test, Level Z , Urbana, IL: Critical Thinking Project, University of Illinois.
Ennis, Robert H., Jason Millman, and Thomas Norbert Tomko, 1985, Cornell Critical Thinking Tests Level X & Level Z: Manual , Pacific Grove, CA: Midwest Publication, 3rd edition.
–––, 2005, Cornell Critical Thinking Tests Level X & Level Z: Manual , Seaside, CA: Critical Thinking Company, 5th edition.
Ennis, Robert H. and Eric Weir, 1985, The Ennis-Weir Critical Thinking Essay Test: Test, Manual, Criteria, Scoring Sheet: An Instrument for Teaching and Testing , Pacific Grove, CA: Midwest Publications.
Facione, Peter A., 1990a, Critical Thinking: A Statement of Expert Consensus for Purposes of Educational Assessment and Instruction , Research Findings and Recommendations Prepared for the Committee on Pre-College Philosophy of the American Philosophical Association, ERIC Document ED315423.
–––, 1990b, California Critical Thinking Skills Test, CCTST – Form A , Millbrae, CA: The California Academic Press.
–––, 1990c, The California Critical Thinking Skills Test--College Level. Technical Report #3. Gender, Ethnicity, Major, CT Self-Esteem, and the CCTST , ERIC Document ED326584.
–––, 1992, California Critical Thinking Skills Test: CCTST – Form B, Millbrae, CA: The California Academic Press.
–––, 2000, “The Disposition Toward Critical Thinking: Its Character, Measurement, and Relationship to Critical Thinking Skill”, Informal Logic , 20(1): 61–84. [ Facione 2000 available online ]
Facione, Peter A. and Noreen C. Facione, 1992, CCTDI: A Disposition Inventory , Millbrae, CA: The California Academic Press.
Facione, Peter A., Noreen C. Facione, and Carol Ann F. Giancarlo, 2001, California Critical Thinking Disposition Inventory: CCTDI: Inventory Manual , Millbrae, CA: The California Academic Press.
Facione, Peter A., Carol A. Sánchez, and Noreen C. Facione, 1994, Are College Students Disposed to Think? , Millbrae, CA: The California Academic Press. ERIC Document ED368311.
Fisher, Alec, and Michael Scriven, 1997, Critical Thinking: Its Definition and Assessment , Norwich: Centre for Research in Critical Thinking, University of East Anglia.
Freire, Paulo, 1968 [1970], Pedagogia do Oprimido . Translated as Pedagogy of the Oppressed , Myra Bergman Ramos (trans.), New York: Continuum, 1970.
Gigerenzer, Gerd, 2001, “The Adaptive Toolbox”, in Gerd Gigerenzer and Reinhard Selten (eds.), Bounded Rationality: The Adaptive Toolbox , Cambridge, MA: MIT Press, pp. 37–50.
Glaser, Edward Maynard, 1941, An Experiment in the Development of Critical Thinking , New York: Bureau of Publications, Teachers College, Columbia University.
Groarke, Leo A. and Christopher W. Tindale, 2012, Good Reasoning Matters! A Constructive Approach to Critical Thinking , Don Mills, ON: Oxford University Press, 5th edition.
Halpern, Diane F., 1998, “Teaching Critical Thinking for Transfer Across Domains: Disposition, Skills, Structure Training, and Metacognitive Monitoring”, American Psychologist , 53(4): 449–455. doi:10.1037/0003-066X.53.4.449
–––, 2016, Manual: Halpern Critical Thinking Assessment , Mödling, Austria: Schuhfried. Available at https://pdfcoffee.com/hcta-test-manual-pdf-free.html; last accessed 2022 07 16.
Hamby, Benjamin, 2014, The Virtues of Critical Thinkers , Doctoral dissertation, Philosophy, McMaster University. [ Hamby 2014 available online ]
–––, 2015, “Willingness to Inquire: The Cardinal Critical Thinking Virtue”, in Martin Davies and Ronald Barnett (eds.), The Palgrave Handbook of Critical Thinking in Higher Education , New York: Palgrave Macmillan, pp. 77–87.
Haran, Uriel, Ilana Ritov, and Barbara A. Mellers, 2013, “The Role of Actively Open-minded Thinking in Information Acquisition, Accuracy, and Calibration”, Judgment and Decision Making , 8(3): 188–201.
Hatcher, Donald and Kevin Possin, 2021, “Commentary: Thinking Critically about Critical Thinking Assessment”, in Daniel Fasko, Jr. and Frank Fair (eds.), Critical Thinking and Reasoning: Theory, Development, Instruction, and Assessment , Leiden: Brill, pp. 298–322. doi: 10.1163/9789004444591_017
Haynes, Ada, Elizabeth Lisic, Kevin Harris, Katie Leming, Kyle Shanks, and Barry Stein, 2015, “Using the Critical Thinking Assessment Test (CAT) as a Model for Designing Within-Course Assessments: Changing How Faculty Assess Student Learning”, Inquiry: Critical Thinking Across the Disciplines , 30(3): 38–48. doi:10.5840/inquiryct201530316
Haynes, Ada and Barry Stein, 2021, “Observations from a Long-Term Effort to Assess and Improve Critical Thinking”, in Daniel Fasko, Jr. and Frank Fair (eds.), Critical Thinking and Reasoning: Theory, Development, Instruction, and Assessment , Leiden: Brill, pp. 231–254. doi: 10.1163/9789004444591_014
Hiner, Amanda L. 2021. “Equipping Students for Success in College and Beyond: Placing Critical Thinking Instruction at the Heart of a General Education Program”, in Daniel Fasko, Jr. and Frank Fair (eds.), Critical Thinking and Reasoning: Theory, Development, Instruction, and Assessment , Leiden: Brill, pp. 188–208. doi: 10.1163/9789004444591_012
Hitchcock, David, 2017, “Critical Thinking as an Educational Ideal”, in his On Reasoning and Argument: Essays in Informal Logic and on Critical Thinking , Dordrecht: Springer, pp. 477–497. doi:10.1007/978-3-319-53562-3_30
–––, 2021, “Seven Philosophical Implications of Critical Thinking: Themes, Variations, Implications”, in Daniel Fasko, Jr. and Frank Fair (eds.), Critical Thinking and Reasoning: Theory, Development, Instruction, and Assessment , Leiden: Brill, pp. 9–30. doi: 10.1163/9789004444591_002
hooks, bell, 1994, Teaching to Transgress: Education as the Practice of Freedom , New York and London: Routledge.
–––, 2010, Teaching Critical Thinking: Practical Wisdom , New York and London: Routledge.
Johnson, Ralph H., 1992, “The Problem of Defining Critical Thinking”, in Stephen P, Norris (ed.), The Generalizability of Critical Thinking , New York: Teachers College Press, pp. 38–53.
Kahane, Howard, 1971, Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life , Belmont, CA: Wadsworth.
Kahneman, Daniel, 2011, Thinking, Fast and Slow , New York: Farrar, Straus and Giroux.
Kahneman, Daniel, Olivier Sibony, & Cass R. Sunstein, 2021, Noise: A Flaw in Human Judgment , New York: Little, Brown Spark.
Kenyon, Tim, and Guillaume Beaulac, 2014, “Critical Thinking Education and Debasing”, Informal Logic , 34(4): 341–363. [ Kenyon & Beaulac 2014 available online ]
Krathwohl, David R., Benjamin S. Bloom, and Bertram B. Masia, 1964, Taxonomy of Educational Objectives, Handbook II: Affective Domain , New York: David McKay.
Kuhn, Deanna, 1991, The Skills of Argument , New York: Cambridge University Press. doi:10.1017/CBO9780511571350
–––, 2019, “Critical Thinking as Discourse”, Human Development, 62 (3): 146–164. doi:10.1159/000500171
Lipman, Matthew, 1987, “Critical Thinking–What Can It Be?”, Analytic Teaching , 8(1): 5–12. [ Lipman 1987 available online ]
–––, 2003, Thinking in Education , Cambridge: Cambridge University Press, 2nd edition.
Loftus, Elizabeth F., 2017, “Eavesdropping on Memory”, Annual Review of Psychology , 68: 1–18. doi:10.1146/annurev-psych-010416-044138
Makaiau, Amber Strong, 2021, “The Good Thinker’s Tool Kit: How to Engage Critical Thinking and Reasoning in Secondary Education”, in Daniel Fasko, Jr. and Frank Fair (eds.), Critical Thinking and Reasoning: Theory, Development, Instruction, and Assessment , Leiden: Brill, pp. 168–187. doi: 10.1163/9789004444591_011
Martin, Jane Roland, 1992, “Critical Thinking for a Humane World”, in Stephen P. Norris (ed.), The Generalizability of Critical Thinking , New York: Teachers College Press, pp. 163–180.
Mayhew, Katherine Camp, and Anna Camp Edwards, 1936, The Dewey School: The Laboratory School of the University of Chicago, 1896–1903 , New York: Appleton-Century. [ Mayhew & Edwards 1936 available online ]
McPeck, John E., 1981, Critical Thinking and Education , New York: St. Martin’s Press.
Moore, Brooke Noel and Richard Parker, 2020, Critical Thinking , New York: McGraw-Hill, 13th edition.
Nickerson, Raymond S., 1998, “Confirmation Bias: A Ubiquitous Phenomenon in Many Guises”, Review of General Psychology , 2(2): 175–220. doi:10.1037/1089-2680.2.2.175
Nieto, Ana Maria, and Jorge Valenzuela, 2012, “A Study of the Internal Structure of Critical Thinking Dispositions”, Inquiry: Critical Thinking across the Disciplines , 27(1): 31–38. doi:10.5840/inquiryct20122713
Norris, Stephen P., 1985, “Controlling for Background Beliefs When Developing Multiple-choice Critical Thinking Tests”, Educational Measurement: Issues and Practice , 7(3): 5–11. doi:10.1111/j.1745-3992.1988.tb00437.x
Norris, Stephen P. and Robert H. Ennis, 1989, Evaluating Critical Thinking (The Practitioners’ Guide to Teaching Thinking Series), Pacific Grove, CA: Midwest Publications.
Norris, Stephen P. and Ruth Elizabeth King, 1983, Test on Appraising Observations , St. John’s, NL: Institute for Educational Research and Development, Memorial University of Newfoundland.
–––, 1984, The Design of a Critical Thinking Test on Appraising Observations , St. John’s, NL: Institute for Educational Research and Development, Memorial University of Newfoundland. ERIC Document ED260083.
–––, 1985, Test on Appraising Observations: Manual , St. John’s, NL: Institute for Educational Research and Development, Memorial University of Newfoundland.
–––, 1990a, Test on Appraising Observations , St. John’s, NL: Institute for Educational Research and Development, Memorial University of Newfoundland, 2nd edition.
–––, 1990b, Test on Appraising Observations: Manual , St. John’s, NL: Institute for Educational Research and Development, Memorial University of Newfoundland, 2nd edition.
OCR [Oxford, Cambridge and RSA Examinations], 2011, AS/A Level GCE: Critical Thinking – H052, H452 , Cambridge: OCR. Past papers available at https://pastpapers.co/ocr/?dir=A-Level/Critical-Thinking-H052-H452; last accessed 2022 07 16.
Ontario Ministry of Education, 2013, The Ontario Curriculum Grades 9 to 12: Social Sciences and Humanities . Available at http://www.edu.gov.on.ca/eng/curriculum/secondary/ssciences9to122013.pdf ; last accessed 2022 07 16.
Passmore, John Arthur, 1980, The Philosophy of Teaching , London: Duckworth.
Paul, Richard W., 1981, “Teaching Critical Thinking in the ‘Strong’ Sense: A Focus on Self-Deception, World Views, and a Dialectical Mode of Analysis”, Informal Logic , 4(2): 2–7. [ Paul 1981 available online ]
–––, 1984, “Critical Thinking: Fundamental to Education for a Free Society”, Educational Leadership , 42(1): 4–14.
–––, 1985, “McPeck’s Mistakes”, Informal Logic , 7(1): 35–43. [ Paul 1985 available online ]
Paul, Richard W. and Linda Elder, 2006, The Miniature Guide to Critical Thinking: Concepts and Tools , Dillon Beach, CA: Foundation for Critical Thinking, 4th edition.
Payette, Patricia, and Edna Ross, 2016, “Making a Campus-Wide Commitment to Critical Thinking: Insights and Promising Practices Utilizing the Paul-Elder Approach at the University of Louisville”, Inquiry: Critical Thinking Across the Disciplines , 31(1): 98–110. doi:10.5840/inquiryct20163118
Possin, Kevin, 2008, “A Field Guide to Critical-Thinking Assessment”, Teaching Philosophy , 31(3): 201–228. doi:10.5840/teachphil200831324
–––, 2013a, “Some Problems with the Halpern Critical Thinking Assessment (HCTA) Test”, Inquiry: Critical Thinking across the Disciplines , 28(3): 4–12. doi:10.5840/inquiryct201328313
–––, 2013b, “A Serious Flaw in the Collegiate Learning Assessment (CLA) Test”, Informal Logic , 33(3): 390–405. [ Possin 2013b available online ]
–––, 2013c, “A Fatal Flaw in the Collegiate Learning Assessment Test”, Assessment Update , 25 (1): 8–12.
–––, 2014, “Critique of the Watson-Glaser Critical Thinking Appraisal Test: The More You Know, the Lower Your Score”, Informal Logic , 34(4): 393–416. [ Possin 2014 available online ]
–––, 2020, “CAT Scan: A Critical Review of the Critical-Thinking Assessment Test”, Informal Logic , 40 (3): 489–508. [Available online at https://informallogic.ca/index.php/informal_logic/article/view/6243]
Rawls, John, 1971, A Theory of Justice , Cambridge, MA: Harvard University Press.
Rear, David, 2019, “One Size Fits All? The Limitations of Standardised Assessment in Critical Thinking”, Assessment & Evaluation in Higher Education , 44(5): 664–675. doi: 10.1080/02602938.2018.1526255
Rousseau, Jean-Jacques, 1762, Émile , Amsterdam: Jean Néaulme.
Scheffler, Israel, 1960, The Language of Education , Springfield, IL: Charles C. Thomas.
Scriven, Michael, and Richard W. Paul, 1987, Defining Critical Thinking , Draft statement written for the National Council for Excellence in Critical Thinking Instruction. Available at http://www.criticalthinking.org/pages/defining-critical-thinking/766 ; last accessed 2022 07 16.
Sheffield, Clarence Burton Jr., 2018, “Promoting Critical Thinking in Higher Education: My Experiences as the Inaugural Eugene H. Fram Chair in Applied Critical Thinking at Rochester Institute of Technology”, Topoi , 37(1): 155–163. doi:10.1007/s11245-016-9392-1
Siegel, Harvey, 1985, “McPeck, Informal Logic and the Nature of Critical Thinking”, in David Nyberg (ed.), Philosophy of Education 1985: Proceedings of the Forty-First Annual Meeting of the Philosophy of Education Society , Normal, IL: Philosophy of Education Society, pp. 61–72.
–––, 1988, Educating Reason: Rationality, Critical Thinking, and Education , New York: Routledge.
–––, 1999, “What (Good) Are Thinking Dispositions?”, Educational Theory , 49(2): 207–221. doi:10.1111/j.1741-5446.1999.00207.x
Simon, Herbert A., 1956, “Rational Choice and the Structure of the Environment”, Psychological Review , 63(2): 129–138. doi: 10.1037/h0042769
Simpson, Elizabeth, 1966–67, “The Classification of Educational Objectives: Psychomotor Domain”, Illinois Teacher of Home Economics , 10(4): 110–144, ERIC document ED0103613. [ Simpson 1966–67 available online ]
Skolverket, 2018, Curriculum for the Compulsory School, Preschool Class and School-age Educare , Stockholm: Skolverket, revised 2018. Available at https://www.skolverket.se/download/18.31c292d516e7445866a218f/1576654682907/pdf3984.pdf; last accessed 2022 07 15.
Smith, B. Othanel, 1953, “The Improvement of Critical Thinking”, Progressive Education , 30(5): 129–134.
Smith, Eugene Randolph, Ralph Winfred Tyler, and the Evaluation Staff, 1942, Appraising and Recording Student Progress , Volume III of Adventure in American Education , New York and London: Harper & Brothers.
Splitter, Laurance J., 1987, “Educational Reform through Philosophy for Children”, Thinking: The Journal of Philosophy for Children , 7(2): 32–39. doi:10.5840/thinking1987729
Stanovich Keith E., and Paula J. Stanovich, 2010, “A Framework for Critical Thinking, Rational Thinking, and Intelligence”, in David D. Preiss and Robert J. Sternberg (eds), Innovations in Educational Psychology: Perspectives on Learning, Teaching and Human Development , New York: Springer Publishing, pp 195–237.
Stanovich Keith E., Richard F. West, and Maggie E. Toplak, 2011, “Intelligence and Rationality”, in Robert J. Sternberg and Scott Barry Kaufman (eds.), Cambridge Handbook of Intelligence , Cambridge: Cambridge University Press, 3rd edition, pp. 784–826. doi:10.1017/CBO9780511977244.040
Tankersley, Karen, 2005, Literacy Strategies for Grades 4–12: Reinforcing the Threads of Reading , Alexandria, VA: Association for Supervision and Curriculum Development.
Thayer-Bacon, Barbara J., 1992, “Is Modern Critical Thinking Theory Sexist?”, Inquiry: Critical Thinking Across the Disciplines , 10(1): 3–7. doi:10.5840/inquiryctnews199210123
–––, 1993, “Caring and Its Relationship to Critical Thinking”, Educational Theory , 43(3): 323–340. doi:10.1111/j.1741-5446.1993.00323.x
–––, 1995a, “Constructive Thinking: Personal Voice”, Journal of Thought , 30(1): 55–70.
–––, 1995b, “Doubting and Believing: Both are Important for Critical Thinking”, Inquiry: Critical Thinking across the Disciplines , 15(2): 59–66. doi:10.5840/inquiryctnews199515226
–––, 2000, Transforming Critical Thinking: Thinking Constructively , New York: Teachers College Press.
Toulmin, Stephen Edelston, 1958, The Uses of Argument , Cambridge: Cambridge University Press.
Turri, John, Mark Alfano, and John Greco, 2017, “Virtue Epistemology”, in Edward N. Zalta (ed.), The Stanford Encyclopedia of Philosophy (Winter 2017 Edition). URL = < https://plato.stanford.edu/archives/win2017/entries/epistemology-virtue/ >
Vincent-Lancrin, Stéphan, Carlos González-Sancho, Mathias Bouckaert, Federico de Luca, Meritxell Fernández-Barrerra, Gwénaël Jacotin, Joaquin Urgel, and Quentin Vidal, 2019, Fostering Students’ Creativity and Critical Thinking: What It Means in School. Educational Research and Innovation , Paris: OECD Publishing.
Warren, Karen J. 1988. “Critical Thinking and Feminism”, Informal Logic , 10(1): 31–44. [ Warren 1988 available online ]
Watson, Goodwin, and Edward M. Glaser, 1980a, Watson-Glaser Critical Thinking Appraisal, Form A , San Antonio, TX: Psychological Corporation.
–––, 1980b, Watson-Glaser Critical Thinking Appraisal: Forms A and B; Manual , San Antonio, TX: Psychological Corporation,
–––, 1994, Watson-Glaser Critical Thinking Appraisal, Form B , San Antonio, TX: Psychological Corporation.
Weinstein, Mark, 1990, “Towards a Research Agenda for Informal Logic and Critical Thinking”, Informal Logic , 12(3): 121–143. [ Weinstein 1990 available online ]
–––, 2013, Logic, Truth and Inquiry , London: College Publications.
Willingham, Daniel T., 2019, “How to Teach Critical Thinking”, Education: Future Frontiers , 1: 1–17. [Available online at https://prod65.education.nsw.gov.au/content/dam/main-education/teaching-and-learning/education-for-a-changing-world/media/documents/How-to-teach-critical-thinking-Willingham.pdf.]
Zagzebski, Linda Trinkaus, 1996, Virtues of the Mind: An Inquiry into the Nature of Virtue and the Ethical Foundations of Knowledge , Cambridge: Cambridge University Press. doi:10.1017/CBO9781139174763

How to cite this entry . Preview the PDF version of this entry at the Friends of the SEP Society . Look up topics and thinkers related to this entry at the Internet Philosophy Ontology Project (InPhO). Enhanced bibliography for this entry at PhilPapers , with links to its database.

Association for Informal Logic and Critical Thinking (AILACT)
Critical Thinking Across the European Higher Education Curricula (CRITHINKEDU)
Critical Thinking Definition, Instruction, and Assessment: A Rigorous Approach
Critical Thinking Research (RAIL)
Foundation for Critical Thinking
Insight Assessment
Partnership for 21st Century Learning (P21)
The Critical Thinking Consortium
The Nature of Critical Thinking: An Outline of Critical Thinking Dispositions and Abilities , by Robert H. Ennis

Accessibility

Support SEP

Mirror sites.

View this site from another server:

Info about mirror sites

Library of Congress Catalog Data: ISSN 1095-5054

IMAGES

Left Brain vs. Right Brain Dominance infographic template. How the
Left Brain vs. Right Brain Dominance
Critical Thinking Skills Chart
Which side of your brain is more dominant?
Right Brain Dominance: Benefits & Characteristics, Right Brain Training
Critical Thinking Definition, Skills, and Examples

VIDEO

The Neuroscience of Human Decisions
UGTRB ENGLISH
Common Barriers to Critical Thinking: Another Unconscious Bias
Riddles That’ll Thrill Your Brain More Than a Math Test
Risk: The Neural Basis of Decision Making
I Want "Proof" of ALIEN Civilizations! Julian Dorey

COMMENTS

Lesson 1.5: The Brain Dominance Theory
It is called the "Brain Dominance Theory," or, technically, Lateralization of Brain Function . This theory suggests that certain approaches to thinking and learning differ according to the hemispheres, left and right, of the brain. Critics of this theory claim it is the result of pop psychology more than sound science.
Left Brain vs. Right Brain: Hemisphere Function
Saul Mcleod, PhD. The left brain is associated with logic, analytical thinking, and language processing, while the right brain is linked with creativity, intuition, and holistic thinking. However, this is an oversimplification, as both hemispheres cooperate in most activities. Hemispheric lateralization is the idea that both brain hemispheres ...
What It Means to Be Left-Brained vs. Right-Brained
Additionally, people are said to prefer one type of thinking over the other. For example, a person who is "left-brained" is often said to be more logical, analytical, and objective. A person who is "right-brained" is said to be more intuitive, thoughtful, and subjective. In psychology, the theory is based on the lateralization of brain function.
1.5: Lesson 1.5: The Brain Dominance Theory
It is called the "Brain Dominance Theory," or, technically, Lateralization of Brain Function. This theory suggests that certain approaches to thinking and learning differ according to the hemispheres, left and right, of the brain. Critics of this theory claim it is the result of pop psychology more than sound science. Indeed, common sense ...
Interplay Between Brain Dominance, Reading, and Speaking Skills in
One of the popular theories in psychology that potentially contributes to the development of teaching and learning programs is brain dominance. According to this theory, the brain is categorized into two hemispheres based on personal traits and cognitive styles. It is interesting to investigate the correlation between brain dominance and second ...
Left Brain, Right Brain: Facts and Fantasies
Left-right asymmetries of brain and behavior are now known to be widespread among both vertebrates and invertebrates [11], and can arise through a number of genetic, epigenetic, or neural mechanisms [12]. Many of these asymmetries parallel those in humans, or can be seen as evolutionary precursors.
Critical Thinking Skills and Brain Dominance of Post ...
The Journal of General Education 50.1 (2001) 1-28 Critical thinking is viewed as a major teaching goal by faculty (Siegal, 1988). When 2,700 teachers from 33 two- and four-year colleges were asked ...
Intuition, insight, and the right hemisphere: Emergence of higher
Abstract. Intuition is the ability to understand immediately without conscious reasoning and is sometimes explained as a 'gut feeling' about the rightness or wrongness of a person, place, situation, temporal episode or object. In contrast, insight is the capacity to gain accurate and a deep understanding of a problem and it is often ...
Lateralization of brain function
The lateralization of brain function (or hemispheric dominance / latralisation) is the tendency for some neural functions or cognitive processes to be specialized to one side of the brain or the other. The median longitudinal fissure separates the human brain into two distinct cerebral hemispheres, connected by the corpus callosum.Although the macrostructure of the two hemispheres appears to ...
Cerebral Dominance
Cerebral Dominance. The concept of cerebral dominance refers to the functional inequality of the cerebral hemispheres. It does not hold that the right hemisphere controls the muscles of the left side of the body or that it receives the bulk ofthe sensory information relating to the left side, andthat theopposite is true for the left hemisphere.
Left Brain vs Right Brain: Definition, Theory, & Differences
Having the left brain dominant. 2. Of or relating to the thought processes, such as logic and calculation, generally associated with the left brain. 3. Of or relating to a person whose behavior is dominated by logic, analytical thinking and verbal communication, rather than emotion and creativity. Right-brained adj: 1.
Left brain and right Brain
Left-Brain or Right-Brain Dominance. According to the theory of left-brain or right-brain dominance, each side of the brain controls different types of thinking. It is thought that people prefer one type of thinking over the other. For example, a person who is "left-brained" is thought to be more logical, analytical, and objective.
Brain Theory
Brain Theory. In the mid-1800's, Paul Broca proposed the classic hemispheric dominance theory that particular characteristics were associated with each side of the brain. Initially, researchers believed the left side of the brain had the higher faculties and was more dominant. By the late 1800's, John Jackson was questioning the left brain ...
Right brain/left brain, right?
These notions of "left and right brain-ness" are widespread and widely accepted. But they may also be wrong. Location matters. There is truth to the idea that some brain functions reside more on one side of the brain than the other. We know this in part from what is lost when a stroke affects a particular part of the brain. For example, it has ...
Left brain vs. right brain: fact or fiction?
However, over time, the left brain vs. right brain dominance theory has proven to be more fiction than fact. In 2013, a team of neuroscientists reviewed Sperry and Gazzaniga's research, along with new evidence, and debunked several previous findings: The human brain does not favor one side over the other. The two sides work differently, but ...
Left Brain vs. Right Brain Dominance: The Surprising Truth
The theory of Left Brain and Right Brain Dominance is very easy to understand. According to this theory, the brain's hemispheres are responsible for controlling different types of tasks and thinking. Furthermore, some people supposedly prefer to think only from one side of the brain, resulting in a difference of opinions and ideas.
PDF Correlating Brain Dominance and Hand Preference to Academic Tracks: A
Pearce (2019) recalled that Sperry discovered the right side of the brain as the weaker and dyslexic side that lacks better cognitive understanding prior to the dominant side while the left side as being more into the analytical and verbal compounds of thinking. This study will also explore the correlation of hand preference to brain dominance
The Secret To A Successful Career Change: Left, Right Brain Dominance
Although we have a dominant side when it comes to problem-solving, play and communication, we utilize both sides of our brain. Comprehending your dominant side is critical; learning to pinpoint ...
Critical Thinking
Critical Thinking. Critical thinking is a widely accepted educational goal. Its definition is contested, but the competing definitions can be understood as differing conceptions of the same basic concept: careful thinking directed to a goal. Conceptions differ with respect to the scope of such thinking, the type of goal, the criteria and norms ...
(PDF) Learning Styles, Brain Dominance and Teaching ...
This case study investigated the learners' brain dominance by employing the s uitable pedagogical. strategies to ensure a high level o f transfer of learning. As to realise the objective, the ...
PDF Learning Styles Brain Dominance and Teaching Techniques ...
Learning Styles Brain Dominance and Teaching Techniques: A Case Study Approach. Responsible Education, Learning and Teaching in Emerging Economies, 4(1), 33-46. Introduction. Many characteristics ...
Left Brain vs Right Brain Dominance: The Surprising Truth
Additionally, people are said to prefer one type of thinking over the other. For example, a person who is "left-brained" is often said to be more logical, analytical, and objective. A person who ...

Lesson 1.5: The Brain Dominance Theory

UNIT 1, EXERCISE 5.2

Left Brain vs. Right Brain: Hemisphere Function

Left hemisphere function

Right hemisphere function

Brain Lateralization

Critical Evaluation

What does the right side of the brain control?

What does the left side of the brain control?

Further Reading

Left Brain vs Right Brain Dominance

Left Brain vs Right Brain Traits

Traits of a Left-Brained Person

Traits of a Right-Brained Person

Theory of Left Brain vs Right Brain Dominance

Click Play to Learn About the Left Brain and the Right Brain

History of Left Brain vs. Right Brain Theory

Left Brain vs. Right Brain Research

Persisting Myths of the Left Brain vs. Right Brain

Rachel Goldman, PhD, FTOS

Improving Brain Health Whether You Feel Left-Brained or Right-Brained

1.5: Lesson 1.5: The Brain Dominance Theory

UNIT 1, EXERCISE 5.2

Intuition, insight, and the right hemisphere: Emergence of higher sociocognitive functions

Organization of this review

Definition of intuition and insight

Social dimensions of intuition and insight

Cognitive science, intuition and insight

Nonverbal decoding and intuition

Intuition is primary and insight is secondary

Emotion, affect, and mood in intuition?

Neural correlates of intuition

Neural correlates of insight

Conscious and unconscious processes

A right hemisphere ventral network in intuition and insight?

Crossed aphasia from the historical perspective

Praxis lateralization and handedness in anomalous subjects

“Resting state” functional lateralization in anomalous subjects

IQ achievement discrepancy and anomalous subjects

Communicative superiority and functional lateralization?

Practical applications of intuition and insight

Conclusions

Limitations

Acknowledgments

Cerebral Dominance

Buying options

Author information

Corresponding author

Editor information

Rights and permissions

Copyright information

About this entry

Download citation

Share this entry

Recent Blog Articles

Right brain/left brain, right?

Recognize yourself?

Location matters

The right-brain/left brain myth?

The bottom line

About the Author

Disclaimer:

Free Healthbeat Signup

Left brain vs. right brain: fact or fiction?

5-second summary

🧠 The basics: how the human brain works

🤔 Myth busting: Is there such a thing as left brain vs. right brain dominance?

🤯 3 brainy facts that will blow your mind and benefit your work

Learning changes the structure of your brain

9 neuroplasticity exercises to boost productivity

Put it to work

Boredom can be beneficial

The surprising, science-backed value of boredom at work

The best ideas happen when we contemplate, then collaborate

put it to work

🪴“When you stop learning, you stop growing.”

Advice, stories, and expertise about work life today.

Bibliography

Critical Thinking

2.1 Dewey’s Three Main Examples