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Stop the Pseudo-Science of Left-Brain/Right-Brain

Susan Notes:

Every year brings us the Edge Question. The 2014 Question is introduced with this observation:

Science advances by discovering new things and developing new ideas. Few truly new ideas are developed without abandoning old ones first. As theoretical physicist Max Planck (1858-1947) noted, "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it." In other words, science advances by a series of funerals. Why wait that long?


Ideas change, and the times we live in change. Perhaps the biggest change today is the rate of change. What established scientific idea is ready to be moved aside so that science can advance?

Here are two people (among 174 respondents) advocating that we retire the notion of Right Brain/Left Brain.

Sarah-Jayne Blakemore
Royal Society University Research Fellow and Full Professor of Cognitive Neuroscience at the Institute of Cognitive Neuroscience, University College London; co-author, The Learning Brain


Most people will have heard about the left-brain/right-brain idea. Maybe they have been told they're too 'left-brained' or want to be more 'right-brained'. The idea has made it into everyday parlance, has infiltrated schools everywhere, sells a lot of self-help books, and has even been used as the basis of scientific theories, for example with regards to gender differences in the brain. Yet it is an idea that makes no physiological sense.

Scientific lingo about how the two sides of the brain--the hemispheres--function has permeated mainstream culture, but the research is often wildly over-interpreted. The notion that the two hemispheres of the brain are involved in different 'modes of thinking' and that one hemisphere dominates over the other has become widespread, in particular in schools and the workplace. There are numerous websites where you can find out whether you are left-brained or right-brained and that offer to teach you how to change this.

This is pseudo-science and is not based on knowledge of how the brain works. While it is true that the brain is made up of two hemispheres and one hemisphere is often initially active before the other during actions, speech and perception, both sides of the brain work together in almost all situations, tasks and processes. The hemispheres are in constant communication with each other and it simply is not possible for one hemisphere to function without the other hemisphere 'joining in', except in certain rare patient populations. In other words, you are not right or left-brained. You use both sides of the brain.

Some people have proposed that education currently favours left-brain modes of thinking, which are supposed to be logical, analytical and accurate, while not putting enough emphasis on right-brain modes of thinking, which are supposed to be creative, intuitive, emotional and subjective. Certainly education should involve a wide variety of tasks, skills, learning and modes of thinking. However, it is just a metaphor to refer to these as right-brain or left-brain modes. Patients who have had a lesion in their right hemisphere are not devoid of creativity. Patients with a damaged left hemisphere might be unable to produce language (which relies on the left hemisphere in over 90% of the population) but can still be analytical.

Whether left-brain/right-brain notions should influence the way people are educated is highly questionable. There is no validity in categorizing people in terms of their abilities as either a left-brain or a right-brain person. In terms of education, such categorization might even act as an impediment to learning, not least because it might be interpreted as being innate or fixed to a large degree. Yes, there are large individual differences in cognitive strengths. But idea that people are left-brained or right-brained needs to be retired.

Stephen M. Kosslyn

Founding Dean, Minerva Schools at the Keck Graduate Institute

Left Brain/Right Brain

Solid science sometimes devolves into pseudoscience, but the imprimatur of being science nevertheless may remain. No better example of this is the popular "left brain/right brain" narrative about the specializations of the cerebral hemispheres. According to this narrative, the left hemisphere is logical, analytic, and linguistic whereas the right is intuitive, creative, and perceptual. Moreover, each of us purportedly relies primarily on one half-brain, making us "left-brain thinkers" or "right-brain thinkers."

This characterization is misguided, and it's time to put it to rest.

Two major problems can be identified at the onset:

First, the idea that each of us relies primarily on one or the other hemisphere is not empirically justifiable. The evidence indicates that each of us uses all of our brain, not primarily one side or the other. The brain is a single, interactive system, with the parts working in concert to accomplish a given task.

Second, the functions of the two hemispheres have been mischaracterized. Without question, the two hemispheres engage in some different kinds of information processing. For example, the left preferentially processes details of objects we see whereas the right preferentially processes the overall shape of objects we see; the left preferentially processes syntax (the literal meaning), the right pragmatics (the indirect or implied meaning) and so forth. Our two hemispheres are not like our two lungs: One is not a "spare" for the other, redundant in function. But none of these well-documented hemispheric differences come close to what's described in the popular narrative.

It is time to move past the popular but incorrect left brain/right brain narrative.

— Sarah-Jayne Blakemore & Stephen M. Kosslyn
The Edge Question


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