Chronometric analysis of classification.

This series of studies represents an effort to extend the subtractive method of Bonders to the analysis of depth of processing in simple classification tasks. The stimuli are always pairs of items (letters, nonsense forms, digits) to which S must respond same or different as quickly as possible. Levels of instruction are physical identity (e.g., AA), name identity (e.g., Aa), and rule identity (e.g., both vowels). By use of the subtractive method, times for matches at each level are analyzed. The emphasis is not placed upon the times themselves but upon their relevance for understanding the operations and mechanisms involved in perceptual matching, naming, and classifying. Nearly 100 years ago the Dutch physiologist Donders presented a paper (Bonders, 1868) on the time for simple cognitive operations. This wellknown paper initiated the use of the subtractive method of latency analysis to measure the time for internal mental processes such as recognition and choice. Although the subtractive method has received a good deal of criticism (Boring, 1950), there is once again active interest in pursuing it. Recent work includes detailed analysis of successive stages in simple reaction time (McGill, 1963), separation of recognition from choice time (Taylor, 1966), effect of task variables such as S-R compatibility upon the component times (Broadbent & Gregory, 1965), and development of dynamic decision models to predict and explain various components of choice time (Fitts, 1966; Stone, 1960).