by G. Wayne Miller and Stephen M. Kosslyn
– Part One: Since Time Immemorial
It will come as no news to those with an interest in neuroscience and psychology that misconceptions and myths about the brain have proliferated since time immemorial (and persist in the modern era, as we discuss in Part Two). The ancient Egyptians thought so little of the brain that they discarded it when mummifying the body in preparation for eternal life. Aristotle believed the brain existed only to cool the blood. Hippocrates got a bit further – but only a bit — with his general observation in “On the Sacred Disease” that the brain is the seat of emotion, pain and anxiety.
Of course, social conventions and the limits of early science restricted those ancient thinkers. By the European Renaissance, prohibitions against cadaver dissection were loosening and the study of mind and brain gained momentum. The 17th-century Dutch anatomist Franciscus Sylvius described an anatomical division of the brain — into its top and bottom parts — that would profoundly interest certain modern scientists. Sylvius’s contemporary Thomas Willis proposed that different large regions of the brain were responsible for different functions. In the 1860s, the Parisian neuroanatomist Pierre Paul Broca provided compelling evidence for the concept of “localization of function,” which holds that different parts of the brain do different things, with his studies of his famous patients “Lelo” and “Tan.”
But this credible science put little dent in pop-psychology’s first fad, phrenology, at least not for years after it took root in the early 1800s. The invention of German physician Franz Joseph Gall, phrenology held that the brain consists of some two dozen or more mental “organs,” each with an individual function — including faculties such as “philoprogenitiveness,” “hope,” “firmness,” “secretiveness” and “individuality.” The larger the size of the relevant brain area, the more developed was the corresponding function. But more than that, the phrenologists asserted that the bumps in the skull overlying each “organ” could be used to assess the efficacy of the underlying faculty. By examining the head with their fingers and various instruments, practitioners claimed to be able to divine aspects of personality and behavior – typically with the goal of self-improvement. Phrenologists charged a fee, of course. Motivated by the timeless quest for happiness, people seeking guidance in relationships, jobs and everyday life readily paid. Thus a template was born.
How popular was phrenology? So popular that Mark Twain included a phrenologist, “the celebrated Dr. Armand de Montalban of Paris,” in The Adventures of Huckleberry Finn. Twain’s phrenologist was a charlatan. Writer Ambrose Bierce also saw through this 19th-century pseudoscience, lampooning phrenology in his satirical book The Devil’s Dictionary as the “science of picking the pocket through the scalp. It consists of locating and exploiting the organ that one is a dupe with.” Skeptics notwithstanding, the fad case a powerful spell. Even today, one can find phrenology charts and busts for sale online and in antique stores – and the state of Michigan not long ago extended its sales tax to include phrenology, along with palm reading and numerology. Someone still maintains the website phrenology.org. “Phrenology is a true science, which is there to benefit humanity,” the site declares.
Phrenology was never accepted inside credible scientific circles because many of its key assumptions are fundamentally incorrect. Specifically: the functions were not described correctly (e.g., “hope” is not localized to a single part of the brain), the size of a brain area does not necessarily reflect its efficacy, and bumps on the skull do not reflect properties of the underlying brain areas. (However, phrenology did have value in helping to reaffirm the concept that functions of the mind are anatomically localized in the brain.) Why, then, did so many lay people embrace it? The answer apparently lies in the timeless yearning we have to understand ourselves and our world. Ancient thinker, contemporary neuroscientist or ordinary person, we seem as a species to be hardwired to attempt to make sense of events and objects that we encounter, even something as complex as the brain. We create narratives, simplifying when necessary. This is not necessarily a bad thing, so long as the narratives are simplified correctly — characterizing core ideas and not introducing misconceptions
In Part Two, we will explore a contemporary parallel to phrenology that persists for much the same reason: our innate desire for meaning.
References
Finger, Stanley. Origins of Neuroscience: A History of Explorations into Brain Function. New York: Oxford University Press, 1994.
Gall, F. J., and J. G. Spurzheim, Anatomie et physionomie du système nerveux en général et du cerveau en particulier. Premier volume. Paris, F. Schoell, 1810; F. J. Gall and J. G. Spurzheim, vol. 2, 1812; F. J. Gall, vol. 3, 1818; F. J. Gall, vol. 4, 1819.
Gross, Charles G. “Early History of Neuroscience.” In Encyclopedia of Neuroscience, edited by George Adelman. Cambridge, MA: Birkhäuser Boston, 1987.
Gross, Charles G. “Aristotle on the Brain.” The Neuroscientist 1 (1995): 245–50.
Molnar, Zoltán. “Thomas Willis (1621–1675), the Founder of Clinical Neuroscience.” Nature Reviews Neuroscience 5 (2004): 329–35.
O’Connor, James P. B. “Thomas Willis and the Background to Cerebri Anatome.” Journal of the Royal Society of Medicine 96 (2003): 139–53.
G. Wayne Miller is an author, filmmaker and Providence (R.I.) Journal staff writer. Visit him at www.gwaynemiller.com. Stephen M. 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.
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– Part Two: Left/right? Wrong.
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 Three 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.
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– Part Three: The Theory of Cognitive Modes
A side view of the brain reveals the top and bottom parts, which are demarcated largely by the Sylvian fissure, the large crease named for Franciscus Sylvanus, the 17th-century Dutch anatomist who first described it. The top brain consists of the parietal lobe and the top (and larger) part of the frontal lobe. The bottom brain includes the remainder of the frontal lobe and the occipital and temporal lobes. Until the 20th century, the importance of this division went largely unnoticed.
This top/bottom division matters because these two parts of the brain have different cognitive functions, a fact first discovered in the context of visual perception and supported in a milestone report in 1982 by National Medal of Science winner Mortimer Mishkin and Leslie G. Ungerleider, of the National Institute of Mental Health. Their trailblazing study examined rhesus monkeys, whose brains process visual information in much the same way as the human brain. Decades of research by many scientists, much of which is with humans, have led to a detailed understanding of the functions of these two parts of the brain.
In brief, the top part of the brain is involved in setting up plans, controlling movements, registering changes in where objects are located in space, and revising plans when anticipated events do not occur. The bottom is involved in classifying and interpreting what we perceive, and allows us to confer meaning on the world. Unlike the left brain/right brain story, a black-and-white dichotomy, The Theory of Cognitive Modes emphasizes the constant and close interaction of the top and bottom systems. They don’t work in isolation – or in competition – but seamlessly together.
We all use both the top and bottom systems, but our Theory of Cognitive Modes holds that we vary in the degree to which we tend to rely on each brain system for functions that are optional – that are not dictated by the immediate situation, such as your reaction to a car speeding in your direction, for example. Nothing in your environment forces you to make subtle and detailed plans — or to ponder the meaning of something in your mind. This kind of optional function is up to the individual.
We define four cognitive modes, based on how highly or minimally a person utilizes the top and bottom brains in optional ways. According to our theory:
•Mover Mode results when a person uses both the top and bottom brain systems in optional ways. People who habitually rely on Mover Mode often are leaders, and prefer situations in which they can plan and act — and be able to react to the consequences of their actions.
•Perceiver Mode results when a person uses the bottom brain system in optional ways, but not the top in such ways. People habitually relying on Perceiver Mode should try to understand in depth what they perceive, putting their experiences in context and drawing the implications. But they do not like to devise detailed and complex plans.
•Stimulator Mode results when a person uses the top but not the bottom brain system in optional ways. People relying on Stimulator Mode may create original, complex plans, but they can also disrupt others’ plans and may stick with their own after it’s clear that their plan should be revised.
•Adaptor Mode results when someone uses neither top nor bottom brain system in optional ways. People thinking in this mode are not absorbed in formulating new plans and don’t spend much time trying to understand their experiences in depth. However, they can use both brain systems effectively when others formulate a complex or detailed plan or define how to interpret objects and events. As such they can be good team members.
You can take a test in our book, and online at www.TopBrainBottomBrain.com, to determine your own dominant mode.
In presenting our Theory of Cognitive Modes, we welcome scrutiny from the scientific community. As we write in the Preface, “Why Another Brain Book?”:
“We intend this book to be accessible to the general reader, but we also hope that it will influence the scientific community. Since neuroimaging burst on the scene in the mid-1980s, many studies of the mind and brain have become noticeably less theory-oriented. Although neuroimaging is a valuable tool in modern neuroscience, it is not always used effectively. Many researchers now simply ask people to perform a cognitive task (such as playing chess or thinking about a particular topic) while their brains are being scanned — and then see which parts of the brain become activated. [We should note that in some cases the scientists also want to provide evidence for a distinction, such as between different ways of thinking.] This approach is radically different from the traditional one, in which the researcher tests specific theories. The traditional approach is important because science makes progress by devising increasingly better theories, and thus it is essential that theories be developed and evaluated. In this book, we seek to return to the hypothesis-driven tradition by proposing a new, plausible, and coherent theory that is strongly rooted in empirical findings.
“We remind the reader at critical points that we are working with a theory, and that rigorous empirical tests of many key predictions have yet to be conducted. We hope that the reader will take the ideas we present as well-founded hypotheses that are worth considering, not as received truth. We also hope that this book will inspire a new round of studies that will further enrich our understanding of how the brain really works.”
References
O. Blazhenkova, M. Kozhevnikov, and M. A. Motes, “Object-Spatial Imagery: A New Self-Report Imagery Questionnaire,” Applied Cognitive Psychology 20 (2006): 239–63.
G. Borst, W. L. Thompson, and S. M. Kosslyn, “Understanding the Dorsal and Ventral Systems of the Human Cerebral Cortex: Beyond Dichotomies,” American Psychologist 66, no. 7 (2011): 624–32.
Melvyn Goodale and A. David Milner “Separate Visual Pathways for Perception and Action,” Trends in Neurosciences 15 (1992): 20–25.
S. M. Kosslyn, “You Can Play 20 Questions with Nature and Win: Categorical Versus Coordinate Spatial Relations as a Case Study,” Neuropsychologia 44 (2006): 1519–23.
S. M. Kosslyn, W. L. Thompson, and G. Ganis, The Case for Mental Imagery (New York: Oxford University Press, 2006).
Kosslyn, Stephen M., and G. Wayne Miller. Top Brain, Bottom Brain: Surprising Insights Into How You Think. New York: Simon Schuster. 2013.
J. G. Rueckl, K. R. Cave, and S. M. Kosslyn, “Why Are ‘What’ and ‘Where’ Processed by Separate Cortical Visual Systems? A Computational Investigation,” Journal of Cognitive Neuroscience 1 (1989): 171–86.
A. Treisman and H. Schmidt, “Illusory Conjunctions in the Perception of Objects,” Cognitive Psychology 14 (1982): 107–41.
Ungerleider, Leslie G., and Mortimer Mishkin. “Two Cortical Visual Systems.” In David J. Ingle, Melvyn A. Goodale, and Richard J. W. Mansfield, eds., Analysis of Visual Behavior, 549–86. Cambridge, MA: MIT Press, 1982.
A. W. Woolley, J. R. Hackman, T. E. Jerde, C. F. Chabris, S. L. Bennett, and S. M. Kosslyn, “Using Brain-Based Measures to Compose Teams: How Individual Capabilities and Team Collaboration Strategies Jointly Shape Performance,” Social Neuroscience 2 (2007): 96–105.