ABSTRACT
The preceding three chapters, 5, 6, and 7, have analyzed the kind and the direction of change. Here, we examine the time course of change. The earlier investigators, Wulf (1922), Perkins (1932), Bartlett (1932), and others, proposed that change was progressive in time. By that they meant first that change increased with time, and second that change was directed, not random. Bartlett thought the direction is toward culturally prescribed schemata, Perkins investigated intrinsic change toward symmetry, and Wulf and Koffka (1935) proposed “leveling” and “sharpening” as the goal of change. The Progressive Change was thought to be due to either extrinsic schemata (Bartlett) or intrinsic structural characteristics of the trace (Wulf, Koffka, Perkins). The experiments to document these changes used repeated reproductions by the same subject over periods of days, weeks, and longer. An example of this procedure is the experiment by Perkins described in the next section.
