Top Brain, Bottom Brain, Part 2 – Left/Right? Wrong

Continued from Part 1. In writing Top Brain, Bottom Brain: Surprising Insights Into How You Think, we invested time in exploring the reasons for the enduring popularity of the left brain/right brain story, which holds that that individuals are either are either logical/analytical or artistic/intuitive based on the “strength” of the brain’s cerebral hemispheres. We knew from daily life that the story was deep-rooted in popular culture — but were surprised by the astounding selection of books, stories, videos, tests, self-help programs, toys and even “essence therapy” devoted to left brain/right brain story. Try a Google search to see for yourself. You could spend hours on the results.

Researchers have long known that science does not support sweeping claims about how people differ in their left and right hemispheres. The functions of the hemispheres are in fact different, but these differences aren’t the stuff of popular lore. Rather, the hemispheres differ in how they process very specific types of information. For example, the left hemisphere processes details of visible objects whereas the right processes overall shape — hardly the sort of difference to fire the popular imagination! We wanted to learn how the great disparity between what science knows and what popular culture has embraced took root and flourished. We felt it would be important background introduction to our new Theory of Cognitive Modes, based on another anatomical division, between the top and bottom parts of the brain.

The hemisphere story grew out of a series of 16 operations in the 1960s and 1970s conducted by surgeons working with lead researcher Roger W. Sperry, a neuroscientist at the California Institute of Technology. The doctors sought relief for intractable epileptics by severing the corpus callosum, the largest structure connecting the left and right hemispheres. The patients did find relief — and in his post-operative studies, Sperry indeed found cognitive differences between the two sides, confirming his earlier experiments with cats and monkeys. He wrote extensively of his findings in the professional literature. Word reached the mainstream press. In a big way.

In 1973, The New York Times Magazine published an article, We are left-brained or right-brained, that ran over 13 pages. “Two very different persons inhabit our heads,” the article began, “residing in the left and right hemispheres of our brains, the twin shells that cover the central brain stem. One of them is verbal, analytic, dominant. The other is artistic…” Time magazine featured the left/right story in 1975. Harvard Business Review in 1976 published “Planning on the Left Side and Managing on the Right” and the next year, Psychology Today came on board. Sperry’s 1981 Nobel Prize in Physiology or Medicine for his split-brain research made these stories all but impossible to ignore.

Three fundamental problems plague the popular narrative about the left brain versus the right brain: First, as mentioned, the functions of the two sides of the brain have been mischaracterized. The left and right hemispheres do indeed have different functions, but they aren’t the sweeping ones of the common narrative. Second, the two sides of the brain always work together. And third, people don’t have a dominant left or right hemisphere. These points are accepted in the scientific community, but have been largely overlooked by mainstream readers. Misconceptions persist despite cautions against over-interpretation of Sperry’s results by respected scientists, including Brenda Milner, of the Montreal Neurological Institute, and Stevan Harnad, founder of the journal Behavioral and Brain Sciences. Sperry himself warned that “experimentally observed polarity in right-left cognitive style is an idea in general with which it is very easy to run wild… it is important to remember that the two hemispheres in the normal intact brain tend regularly to function closely together as a unit” in an essay published in Neuropsychologia in 1984.

By then, the proverbial horse had left the barn: the popular culture had found a simple and seemingly logical narrative that offered answers in the age-old quest for understanding and also practical applications for everyday life. The advent of the Internet with its power to reach and inform – and misinform – the masses canonized the story, alongside such lesser myths as the one that we use just 10 percent of our brains (when in fact every region of a healthy brain is used, as brain scanning demonstrates) and the one that even moderate amounts of alcohol kill neurons (excessive drinking can, however, damage dendrites).

With publication of our book by a major mass-market publisher, we introduce to the broader community another theory of brain function based on an anatomical division of the brain — but not into its left and right hemispheres. By doing so, a legitimate question is posed: do we fall victim to the same problems as the left brain/right brain story? Are we launching our own myth?

Needless to say, our answer is no, as we explain in Part 3 of this series.


Goleman, Daniel. “Split-Brain Psychology—Fad of the Year.” Psychology Today 11 (1977): 88–90.

Harnad, Stevan, and Horst D. Steklis. “Comment on J. Paredes and M. Hepburn’s ‘The Split Brain and the Culture-and-Cognition Paradox.” Current Anthropology 17 (1976): 320–22.

Milner, Brenda. “Interhemispheric Differences in the Localization of Psychological Processes in Man.” British Medical Bulletin 27 (1971): 272–77.

Pines, Maya. “We Are Left-Brained or Right-Brained; Two Astonishingly Different Persons Inhabit Our Heads.” New York Times Magazine, September 9, 1973

Sperry, Roger W. (1961). “Cerebral Organization and Behavior: The Split Brain Behaves in Many Respects Like Two Separate Brains, Providing New Research Possibilities.” Science 133 (1961): 1749–57.

“Lateral Specialization in the Surgically Separated Hemispheres.” In Third Neurosciences Study Program, edited by F. Schmitt and F. Worden, 5–19. Cambridge, MA: MIT Press, 1974.

“Some Effects of Disconnecting the Cerebral Hemispheres.” Nobel Lecture, Nobel Prize in Physiology or Medicine 1981, www .nobelprize .org /nobel prizes /medicine /laureates /1981 /sperry-lecture_en.html #.

“Consciousness, Personal Identity and the Divided Brain.” Neuropsychologia 22 (1984): 661–73.

Image via Eskymaks / Shutterstock.

  • I appreciate the information shared here, yet Miller and Kosslyn, in everything I have read so far, have missed an important piece of this picture in neglecting the work of Iain McGilchrist on the divided brain (The Master and His Emissary; The Divided Brain; and numerous videos of his talks). In his 20 years of meticulous research, he would agree that old version of left/right isn’t accurate, but that there is still a distinct and compelling difference in the way the two hemispheres attend to the world. Said very briefly (and therefore not doing it any kind of justice), the right attends to the space between, the relational world unfolding in this moment, both/and, comfortable with paradox, and the left reprocesses information, rendering it lifeless for the sake of being able to create systems, either/or, unaware of the embodied world in the moment. Both are essential, and if the relationship between them is that the right offers the vision and the left creates the systems to manifest it, all is well. If the left goes off on its own, we create a dehumanized, more mechanical, more simplistic world. I wonder how these two authors might revise their own theory in light of this.

    My other struggle with the top-brain/bottom-brain theory is this. In what I have read so far (and I have not read the book, but only several articles), the top brain is thought of as being devoted to planning and goals. My understanding is that for the left prefrontal and accompanying circuits this is mostly true, but the right prefrontal and its companions are very concerned with relationship, attachment, autobiographical felt sense narrative, integrating body awareness, and much more. So it seems like their theory primarily embraces half of the top-brain and all of the bottom (perceptual) brain. So to circle back to McGilchrist’s argument (as I understand it), it would appear that Miller and Kosslyn are attending from a left hemisphere perspective which has the possibility of leaving out (not seeing) the viewpoint from the right. We all have our biases and the best we can probably do is become aware of them. I would like to acknowledge mine. My work largely focuses around attachment and a more right-focused way of attending, so I am more sensitive to that than to the left-focused way of attending. I am sure that biases both the way I read Miller and Kosslyn as well as informs my response.

  • Bonnie, hi. I had the same reaction, and found this fascinating back and forth critique between McGilchrist and Kosslyn / Miller, on Iain’s site.

    • Thank you, William. Yes, I had read the conversation and that was one of the reasons I was moved to write this. It didn’t seem to me that Kosslyn and Miller were very responsive to what Iain was saying, so thought I would try again. It’s comforting to hear that there are others sensing the same thing.

  • Pingback: Brain Misconceptions, Brain Realities. | Brain Blogger()

G. Wayne Miller and Stephen M. Kosslyn, PhD

G. Wayne Miller is an author, filmmaker and Providence (R.I.) Journal staff writer. Visit him at Stephen M. Kosslyn, PhD, 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.

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