Kenneth W. Spence (1907-1967) played a major role in psychology from the early 1930s until his untimely death. His impact is illustrated by the fact that from 1962 to 1967, he was the most cited author in a survey of the fourteen most prestigious psychological journals (Myers, 1970). Spence's influence resulted from achievements as experimentalist, theorist, methodologist, and teacher. In all of these roles, he operated as a natural science psychologist, one who believed that the science of psychology can employ the same methods of empirical inquiry and theory construction as physics, chemistry, and biology. In essence, he was asserting that psychology, in principle, is capable of producing a body of reliable scientific knowledge. To achieve this goal he deemed it necessary to conceptualize psychology as the science of behavior, not of the mind. That is, the basic observations of the science of psychology are the behavior...