This chapter describes the theories of Clark Hull, who had an enormous influence on American psychology from the time he first wrote about - and reinterpreted - Pavlovs work in the early 1930s to well into the 1960s. Hulls ambition was to develop a general theory of learning and motivation based on the development of habits - as studied mainly in rats - that would provide psychology with the equivalent of Newtons contribution to physics. His vision inspired some of the brightest and most productive researchers into animal learning in the 1950s and 1960s. Important topics that the neo-Hullians studied included the partial reinforcement extinction effect and conditioning of visceral responses.

Behavioral psychology was immediately preceded by the reflexology of Russian physiology and the associationism of Thorndike. Physiological reflexology received a sound foundation with the works of Sechenov and Bekhterev, but it was Pavlov who proposed a comprehensive theory of conditioning. Watson’s behavioral formulation defined stimulus and response elements as the substitute to rid psychology of residual mentalistic constructs. Watson’s contemporaries, Holt, Weiss, Hunter, and Lashley, soon restored to behaviorism critical psychological activities. The logical positivist movement expressed an operational spirit and insured the initial success of the behaviorist model. Behavioral psychology expanded beyond the original formulations of Pavlov and Watson. Contemporary reflexology in Russia and in nearby countries expanded to include a wide range of psychological and physiological problems, led by such eminent scientists as Vygotsky, Luria, Konorski, Asratyan, and Beritashvili. In the United States, behaviorism moved through several intellectual stages, through the contributions of Guthrie, Tolman, Hull, and Skinner. A major application of behaviorism was the behavior modification model in clinical settings. Contemporary behaviorism remains a dominant but diffused force in psychology.