David Premack Ph.D. is emeritus professor of psychology at the University of Pennsylvania. A pioneer, with Ann, in chimpanzee language study, they showed why chimps cannot acquire human language. Premack proposed a theory of reward or reinforcement still used after forty years (Premack Principle), and introduced the concept of "Theory of Mind," a keystone of human social intelligence. His book "The Mind of an Ape," which he wrote with Ann Premack, summarized his work on animal intelligence and was given an award by the American Psychological Association. Ann Premack's book "Why Chimps Can Read...