There Is No Left Brain/Right Brain Divide

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You are hardly alone if you believe that humanity is divided into two great camps: the left-brain and the right-brain thinkers — those who are logical and analytical vs. those who are intuitive and creative. For years, an industry of books, tests and videos has flourished on this concept. It seems to be natural law.

Except it isn’t.

Scientists have long known that the popular left brain/right brain story doesn’t hold water. Here’s why. First, the sweeping characterizations of the two halves of the brain miss the mark: one is not logical and the other intuitive, one analytical and the other creative. The left and right halves of the brain do function in some different ways, but these differences are more subtle than is popularly believed. (For example, the left side processes small details of things you see, the right processes the overall shape.) Second, the halves of the brain don’t work in isolation; rather, they always work together as a system. Your head is not an arena for some never-ending competition, the brain’s “strong” side tussling with its “weak.” Finally, people don’t preferentially use one side or the other.

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The roots of the left/right story lie in a small series of operations in the 1960s and 1970s by doctors working with Roger W. Sperry, a Nobel-laureate neuroscientist at the California Institute of Technology. Seeking treatment for severe epilepsy, 16 patients agreed to let the doctors cut the corpus callosum, the main nerve bundle that joins the two halves of the brain. They found some relief from these dramatic visits to the OR — and when they left the hospital, they allowed Sperry and his team to study their cognitive functioning.

Laboratory findings do not always make their way into the popular culture, but these did, which provided an unfortunate opportunity for misinterpretation of what was, in essence, a limited set of experiments. In 1973, the New York Times Magazine published an article titled, “We Are Left-Brained or Right-Brained,” which began: “Two very different persons inhabit our heads … One of them is verbal, analytic, dominant. The other is artistic …” TIME featured the left/right story two years later. Harvard Business Review and Psychology Today jumped in. Never mind that Sperry himself cautioned that “experimentally observed polarity in right-left cognitive style is an idea in general with which it is very easy to run wild.” A myth spread.

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Myths, of course, are a timeless way to make sense of experience. In the search for meaning, people may create simplified narratives. This is a reasonable strategy, but the right brain/left brain narrative introduced misconceptions.

We have developed a new theory built on another, frequently overlooked anatomical division of the brain, into its top and bottom parts. Among other things, the top part sets up plans and revises those plans when expected events do not occur; the bottom classifies and interprets what we perceive.

Based on decades of research, the theory holds that this distinction can help explain why individuals vary in how they think and behave. We all use both parts of the brain but differ in how deeply we use each part. The key is the way the parts interact, not each part by itself. Depending on the extent to which a person uses the top and bottom parts, four possible cognitive modes emerge. These modes reflect the amount that a person likes to devise complex and detailed plans and likes to understand events in depth. (You can determine your own dominant mode with this test.)

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This new approach avoids the pitfalls of the left brain/right brain story for several reasons. The characterizations of what each part does are based on years of solid research. We emphasize that the two parts always work together — it’s the relative balance of how much people use the two parts that determines each cognitive mode. And we stress that the parts of the brain don’t work alone or in competition but seamlessly together. In some ways this theory too is a simplification, but one that brings more understanding. If there’s one thing we do know, it’s that as a species, we are continually inclined to try to understand what we encounter, even something as complex as the brain.

Kosslyn is a cognitive neuroscientist and was professor of psychology at Harvard University for over 30 years; he now serves as the founding dean of the Minerva Schools at the Keck Graduate Institute. Miller is an author, filmmaker and Providence Journal staff writer. They are the co-authors of Top Brain, Bottom Brain: Surprising Insights Into How You Think.


Interestingtheory,thewonderofthemindstillnotusshowsitsfullpotential.It isaworldwithoutborders,butsometimes,notisitissonecessary to wanting tounderstandorknowtheunfathomable,maybeonlyseeusbetheunknown.


Iain McGilchrist's book (The Master and his Emissary) is filled with hundreds of references that explain this in detail. There has been clear oversimplification in popular media, but the lateralization of narrow vs. holistic perspectives has clearly been shown. This animated Youtube from one of Iain's lectures is outstanding, .

Here is a back and forth exchange of critiques by McGilchrist and Kosslyn / Miller,


Although I agree that no part of the brain acts in isolation, this article misses some very important imaging studies from Japan, as well as extensive research by Dr. Linda Silverman regarding learning styles and Dr. R. Fedler who has done extensive validation studies for a "learning style" identifying inventory.

 Kuriki et al (1996), noted that there is most definitely more activity in the right hemisphere during reading of Chinese or Japanese logographics in comparison to alphabet, bottom-up languages like English, German, French. Characteristics of left-brain thinking or the sequential-verbal learning style, include a preference for step-by-step learning, emphasis or procedure and plug-in formulae, highly organized environments and conservatism.This preference reflects the process of linguistic analysis of bottom -up languages, characterized by a process of building words by adding morphemes until the desired meaning is achieved {the smallest language component that carries meaning like "s" which signifies plural} (Kierans, 1991; Silverman, 1989). 

By way of contrast, languages that are pictographic or syllabic in nature require a top down information processing strategy as one symbol can represent a word or concept. It may be that for these individuals the routine use of global information processing strategies leads to a more holistic thinking style, promoting greater synthesis abilities instead of analysis of information (Zhang, 2002). Further, research indicates that in global languages, like Chinese and Japanese, the left hemisphere is activated for the phonological aspect of reading but lateralization for graphical processing is to the right hemisphere. This is attributed to the intensive demands for visuospatial analysis required by the logographs’ square configuration (Kuriki et al.1996; Tan et al.2001).

This view is consistent with Ross (2003;2004) who proposed that language and cognition are not isolated phenomena but rather that there is a triarchic relationship where cognition, language and culture interact and act on each other, hence the Sapir-Whorf hypothesis, that language influences how we perceive the world is valid and that culture also acts as a significant contributing factor in how we learn and process new information. 

This "lateralization",[ not a term I agree with because it implies complete autonomy between hemispheres rather than interdependence and autonomy simultaneously], is more evident in individuals with early onset bilingualism, especially in those individuals who speak both a top-down language and a bottom-up language. I have witnessed by daughter switch from English to Japanese and have noted that her whole demeanor and personality changes when she switches. This is consistent with the research that suggests that certain characteristics like demeanor, political view, level of gregariousness, etc are different in L1 than L2. I suspect that, rather than support the hypothesis that there is no difference in brain activity patterns between the 2 "information processing" styles, that we may discover that there is a right hemisphere equivalent to the Werneke area that processes top-down languages and may be at play in the pattern observed in some individuals, who are more visual-spatial in their thinking, of taking less time to process the written word because they skip the phonological loop when processing language and go straight to the lexicon.

This being said, in European languages and cultures, the auditory -sequential learning style is more prevalent in general but the visual-spatial learning style is more common in gifted individuals (70%). I would suggest that the studies referred to in this article did not control for this phenomenon and so is only generalizable for 60% of the population and in other groups like Asians and Native Americans where the prevalence of the visual-spatial learning style is between 80 and 90%. This is the problem with having scientific research published in popular press, there is no peer review and study results are not put in their proper context, Samples, especially in psychological studies tend to have very small samples, 25 is not uncommon and therefore cannot be generalized to the rest of the population until the study has been replicated several times with different researchers and participants so that the results are more reflective of what is really out there. It is very easy to manipulate the data to reflect the results we want. A perfect case in point is the misbranding of Risperidone and other second generation antipsychotics as being safe and effective for paediatric use based on the findings of a few case studies (n=1) and carefully controlled short term studies (<25) which stopped before the subjects would express the structural changes in brain structure often in their teen years) due to the influence of the drug on brain development. More recently the APA has come forward and condemned the off-label prescribing of antipsychotics to children and adolescents who do not have a psychotic disorder diagnosis. And the authors of these studies have attempted to retract their results from the peer reviewed journals.

One should always be extremely careful of the validity of studies and refrain from making sweeping generalizations based on crumbs of data resulting from questionable methodology.



"You are hardly alone if you believe that humanity is divided into two great camps: the left-brain and the right-brain thinkers — those who are logical and analytical vs. those who are intuitive and creative."

Anyone who thinks this has to be true has clearly never really watched classic "left-brain" people, like real-life scientists, mathematicians, engineers, and computer programmers, at work.  Because if they had, they'd realize that these people, despite being very logical and analytical, also MUST be both intuitive and creative merely to get their jobs done, much less to excel at them and get satisfaction from them.  


Left and right brain have been used metaphorically by many to explain the concept that various functions are associated with different parts of the brain.


Unfortunately the argument about left/right brain workings did not originate in California as the author says - it began in Montreal when Dr. Wilder Penfield, neurosurgeon and founder of the Montreal Neurological Institute postulated, after many operations during which patients were sedated only for the initial opening of their skulls, but were conscious and responsive during surgery, about the two sides of the brain and their differing 'jobs'.  He did not suggest that they work independently or only one at a time, but in any case, was the initiator of the left/right brain concept.  For the record.


L/R brain use does exist.   Even though the motor neurons exist in both hemispheres, only one side is used.    This has been proven millions of times with stroke survivors.     Left half,  right body  - and vice versa.    

Many studies (research and clinical)  have proven that generally 'female' brains are more able to adapt to using/training the other hemisphere when the one normally used has been damaged with cell death (stroke, trauma, etc.).

Yes both hemispheres have the potential of symmetrical functions.   But only one side is preferred and used the most.    E.g.,  both hands can be used to write.     99.9% of humans only use one hand.   

Agree, however, that assigning personality/character traits to L or R handed-ness is insane.     Those who primarily use their Right brain to be believed as more touchy/feely/artsy is equally as insane as determining that anyone who is left-handed is "evil".


@IliveahWaters1 so what happens if a misfunction makes it that both halves are equally prefered and work simultaneously?

Some speech therapists say this is why some people stammer.