Most generally, behaviorism is a viewpoint that takes psychological phenomena as physical activity rather than as belonging to a special domain of mental events. For a behaviorist, then, psychology is the study of behavior and its physical, mainly environmental, determinants rather than of the nature of experience or of mental process. Behaviorism originated in natural-science traditions of the late nineteenth century, and precursors of its methods and concepts developed at the turn of the century in the work of E. L. Thorndike and Russian physiologist I. P. Pavlov, as well as of several other psychologists and physiologists (Day, 1980; Herrnstein, 1969).

But behaviorism as a distinct viewpoint came to be recognized with the publication of American psychologist John B. Watson's article "Psychology as the Behaviorist Views It" (1913). Identification of behaviorism with the controversial Watson persists despite the fact that it developed into several distinct traditions that bear only a family...