A reappraisal of the roles of past experience and innate organizing processes in visual perception.

Twenty years ago, in his Principles of Gestalt Psychology, Kurt Koffka posed the problem of visual perception in the succinct question, "Why do things look as they do?" He took issue with the usual answer that things look as they do because of our past experience with them, arguing that an empiristic theory not only failed to account for many of the facts of visual perception, but, in addition, entailed a number of logical difficulties. Few of Koffka's arguments have been satisfactorily met; nevertheless, two decades later, a survey would show that his analysis has had little or no impact on the psychological literature dealing with this problem. For example, a widely used textbook states: "With the few possible exceptions provided by primitive organizations, all perceiving is dependent upon past experience—the so-called habit factor" (45, p. 410). Moreover, the empiristic theory has reemerged in the currently popular assumption that perceptions are governed by motivational and affective forces; in this remodeling, however,