Continued from Part 2.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 17^th-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 20^th 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

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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.

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