Born Jan. 9, 1878, in Greenville, S.C.; died Sept. 25, 1958, in New York. American psychologist and founder of behaviorism.

Watson was a professor at Johns Hopkins University in Baltimore from 1908 to 1920. His ideas, which were based on animal studies, represented a reaction to the methods of introspective psychology. In Watson’s view, psychology was to be regarded as one of the natural sciences and should apply the latter’s objective experimental methods. He treated all psychological activity as behavior, which was interpreted as the sum of “stimulus-response” relationships. According to Watson, the organism is a “self-organizing machine,” and the main task of psychology is to study the processes of learning. Even thought was regarded by Watson as a hidden motor activity and as a substitute for action.

Watson’s ideas and methods greatly influenced the development of psychology, especially in the USA, but have come under criticism in contemporary psychology for being mechanistic and limited.