Skinner, Burrhus Frederic - 1904–90, American psychologist, b. Susquehanna, Pa. He received his Ph.D. from Harvard in 1931, and remained there as an instructor until 1936, when he moved to the Univ. of Minnesota (1937–45) and to Indiana Univ., where he was chairman of the psychology department (1945–48). He returned to Harvard in 1948, becoming the Edgar Pierce Professor of Psychology in 1958. Skinner was the leading exponent of the school of psychology known as' behaviorism' which explains the behavior of humans and other animals in terms of the physiological responses of the organism to external stimuli. Like other behaviorists, he rejected unobservable phenomena of the sort that other forms of psychology, particularly 'psychoanalysis' had studied, concerning himself only with patterns of responses to rewards and stimuli. Skinner maintained that learning occurred as a result of the organism responding to, or operating on, its environment, and coined the term operant conditioning to describe this phenomenon. He did extensive research with animals, notably rats and pigeons, and invented the famous Skinner box, in which a rat learns to press a lever in order to obtain food. Skinner's more well-known published works include The Behavior of Organisms (1938), Walden Two (1948), Beyond Freedom and Dignity (1971), and About Behaviorism (1974, repr. 1976).