Stimulus intensity effects on auditory and visual reaction processes.

Literature on the effect of stimulus intensity on reaction processes was reviewed. It was shown that there is no agreement as to whether intensity effects are limited to encoding or whether they are extended to later processing stages. The situation can be characterized as an asymmetry between modalities: vision is consistent with the first alternative and audition with the second.Chronometric analysis was used to bear on the question. It was shown that the effects of visual intensity and foreperiod (FP) are additive in a simple RT situation both for constant and mixed blocks FP. Auditory intensity and FP interact in both simple and two-choice situations. In a control experiment visual intensity and S-R compatibility were found to be additive. The asymmetry was accounted for by auditory alerting, previously discussed by several authors.The framework of stimulus intensity research utilizing RT measures was briefly evaluated.