Effects of stimulus intensity on the lateralized readiness potential

Information-processing models differ about whether stimulus intensity affects the speed of motor processes involved in response activation and execution. Previous studies of intensity are reviewed, but they are not decisive on this point because they have used indirect approaches requiring strong assumptions. Two experiments examined the effects of stimulus intensity on the lateralized readiness potential (LRP), a measure of hand-specific response activation. In Experiment 1, visual stimulus intensity influenced the time from stimulus onset to LRP onset but not the time from LRP onset to the keypress response. In Experiment 2, auditory stimulus intensity did not influence either of these Lime intervals, although it did influence the time from stimulus onset to the N100 and P300 components of the evoked potential. The results indicate that stimulus intensity does not influence the duration of motor processes in choice reaction time tasks.