ABSTRACT
Throughout his career, Bill Estes has worked on refining theories of how rewards and punishments operate to shape and control organisms' behavior. From his earlier training with B. F. Skinner, Estes acquired a firm commitment to studying the way incentives and reinforcement schedules control behavior in lower organisms; and his later concern with human learning led him into careful study of the research papers of Edward L. Thorndike. Thorndike was an extremely important figure in learning theory in the 1920–1945 period and Estes was a student in the later years. Thorndike's proposed “Law of Effect” was to serve as the focal point around which revolved most studies of reinforcement and learning (Thorndike, 1931).
