Stimulus Categorization and Response Time

Abstract

Generally, in disjunctive reaction time experiments there is a one-to-one correspondence between the number of stimulus alternatives and the number of response alternatives. Consequently, the roles of stimulus recognition or categorization processes and response choice processes are confounded in the data. Two experiments were conducted in which the stimulus set was mapped onto the response set in a many-to-one-fashion. In each case S's task was to press a key in response to those stimuli designated as “critical” and to not press the key in response to stimuli designated as “non-critical.” In the first experiment RT increased monotonically as the number of different stimuli in the critical stimulus category was increased from one to four. In the second experiment RT varied with the number of independent disjunctively combined attributes used to designate the critical category.