Stephen Michael Kosslyn (born 1948) is an American psychologist who specializes in the fields of cognitive psychology and cognitive neuroscience. Until 31 December 2010 he was John Lindsley Professor of Psychology in Memory of William James and Dean of Social Science at Harvard University, having previously been chair of the Department of Psychology at Harvard University. As of 1 January 2011, he became director of the Center for Advanced Study in the Behavioral Sciences at Stanford University.

Kosslyn received his B.A. in 1970 from UCLA and his Ph.D. in 1974 from Stanford University, both in psychology. His Ph.D. advisor was Gordon Bower. His former teaching career includes Johns Hopkins and Brandeis Universities.

In this groundbreaking contribution to the literature of human personality, a celebrated psychologist and an award-winning author offer an exciting new way of thinking about our minds—and ourselves—based on a new way of looking at the brain.With cowriter G. Wayne Miller, Dr. Stephen M. Kosslyn, a leader in the field of cognitive neuroscience, explains an exciting new theory of the brain for the first time. Summarizing extensive research in an inviting and accessible way, Kosslyn and Miller describe how the top and bottom parts of the brain work together, producing four modes of thought: Mover, Adaptor, Stimulator, and Perceiver. These ways of thinking and behaving shape your personality, and with the scientifically developed test provided in the book, you’ll quickly be able to determine which mode best defines your dominant mode of thought. Once you’ve identified your dominant cognitive mode, the possible practical applications are limitless, from how you conduct business, to your romantic relationships, to your voyage of personal discovery.

For the past fifty years, popular culture has led us to believe in the left brain vs. right brain theory of personality types. Right-brain people, we’ve been told, are artistic, intuitive, and thoughtful, whereas left-brain people tend to be more analytical, logical, and objective. It would be an illuminating theory if it did not have one major drawback: It is simply not supported by science. In contrast, the new theory is based on solid research that has stayed within the confines of labs all over the world—until now.