A pioneer in re-introducing physiology as a determinate of psychological characteristics, Jerome Kagan has taught both undergraduate and graduate students for more than 35 years. For the past 20 years, he and his students have been working intensely on the relation between the infant temperamental qualities of high and low reactivity and the subsequent development of variation in mood and behavior that have come to be called "inhibited" and "uninhibited."

Born in Newark, N.J., in 1929, Kagan earned his undergraduate degree from Rutger's University (1950) and was awarded a Ph.D. in psychology from Yale University (1954). Research undertaken at the Fels Research Institute led to his first book, Birth to Maturity (1962), a landmark study of the degree to which personality traits are carried from infancy and childhood to adolescence and beyond, and a deep curiosity about inhibited and uninhibited children. Since 1964, he has taught at Harvard University, where he has held the Daniel and Amy Starch chair in psychology. From 1997 to 2000, he was co-director of the university-wide "Mind-Brain-Behavior" initiative at Harvard.

Among Kagan's many books and other publications are Unstable Ideas: Temperament, Cognition, and Self (1989); Galen's Prophecy (1994), which suggests that the second-century Roman physician Galen was correct in attributing temperamental differences to both inheritance and environment; and Three Seductive Ideas (1998), which argues against "infant determinism."