Influence of stimulus and response probability on decision and movement latency in a discrete choice reaction task.

Abstract

Varied the relative frequencies of occurrence of 4 stimuli and 2 responses in a discrete choice reaction task with 8 female and 10 male undergraduates. With circles of differing diameter or letters as stimuli, decision time (DT) was significantly shorter for high- than low-frequency stimuli and responses. Movement time (MT) showed corresponding differences with letters, while for the circles only the effect of stimulus frequency bias was significant. The changes in DT with the introduction of stimulus and response bias are interpreted as arising at the stimulus-processing and response-selection stages, respectively. The differences in MT are attributed to the occurrence of erroneous decisions, occurring at either stage, which are corrected before completion of the response. (18 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)