Is one of the key pioneers of developmental psychology. He is Daniel and Amy Starch Research Professor of Psychology, Emeritus at Harvard University, and co-faculty at the New England Complex Systems Institute. He has shown that an infant's "temperament" is quite stable over time, in that certain behaviors in infancy are predictive of certain other behavior patterns in adolescence. Kagan was listed as the 22nd most eminent psychologist of the 20th Century, just above Carl Jung.^{[1]  (from Wikipedia)}