Effects of stimulus intensity on the lateralized readiness potential

Information-processing models differ about whether stimulus intensity affec ts the speed of motor processes involved in response activation and executi on. Previous studies of intensity are reviewed, but they are not decisive o n this point because they have used indirect approaches requiring strong as sumptions. Two experiments examined the effects of stimulus intensity on th e lateralized readiness potential (LRP), a measure of hand-specific respons e activation. In Experiment 1, visual stimulus intensity influenced the tim e from stimulus onset to LRP onset but not the time from LRP onset to the k eypress response. In Experiment 2, auditory stimulus intensity did not infl uence either of these Lime intervals, although it did influence the time fr om stimulus onset to the N100 and P300 components of the evoked potential. The results indicate that stimulus intensity does not influence the duratio n of motor processes in choice reaction time tasks.