Effects of certainty and uncertainty of stimulus-response correspondence on auditory reaction times.

Complex reaction time (RT) was measured for a task in which a discriminative auditory cue designated whether the right or left hand was to be used in responding. Facilitation of monaural RT compared to binaural RT occurred on trials in which both (1) the ear stimulated corresponded to the hand specified for response and (2) each of 20 male college students had received a prior signal signifying that stimulus-response correspondence would occur on the trial. RT was slower for monaural than binaural input when the monaural stimulus was applied to the ear contralateral to the hand designated by the tonal cue regardless of a prior signal signifying that stimulus-response noncorrespondence would occur on the trial. These slower RTs were attributed to an inability of subjects to inhibit their initial tendency to react toward the source of stimulation.