In the years since Pavlov's work first became known in the United States (Pavlov, 1906; Yerkes & Morgulis, 1909), the least controversial assessment of his contributions is the recognition that he provided psychology with not only a method, but an elucidation of the many conditions affecting the formation and retention of learned responses and an objective terrninology for their description (for example, conditioning itself, conditioned and unconditioned stimuli, reinforcement, stimulus generalization, extinction, spontaneous recovery, differentiation). Pavlov's terms are, in fact, still regarded by investigators of 1earning as being among the most basic descriptive units of behavior, applicable even in learning paradigms other than classical conditioning. Moreover, by virtue of his objective, deterrninistic, and Darwinian frame of reference, Pavlov's method of investigation, empirical findings, and concepts have had a persistent and broad impact not only upon learning psychologists, but also upon the wider psychological community. Unfortunately, this impact has been colored by numerous misconceptions of classical conditioning, which have accumulated and ramified to the point where even the mere specification of the method of classical conditioning has become ambiguous and controversial. The source of many of these misconceptions can be found in the wide and uncritical acceptance of the findings of Pavlov and his more psychologically oriented Russian contemporary, Bekhterev.