Response latencies are determined by the current stimulus and the current response criterion

Abstract

There has been a recent renewal of interest in the response latency as a psychophysical index of detectability, discriminability, or perceptual magnitude. This response measure depends on a number of variables other than those of the stimulus and thus some care is required in its interpretation. It has been proposed that one of the most powerful determinants of response latency in discrimination tasks should be the distance of the current stimulus from the current criterion, measured along a decision axis. This proposition was demonstrated in nine experimental conditions, in which the tasks were (a) a difficult frequency discrimination, (b) an easy frequency discrimination, and (c) assignment of a two digit number to the correct one of two distributions. Each of these stimulus conditions was tested (1) in a standard statistical decision procedure, (2) with the optimal criterion demonstrated on each trial, and (3) in a “labeling” procedure without real or implied rewards. In all cases the response latencie...