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.

References

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.

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 www.gwaynemiller.com. 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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