Evidence from auditory simple reaction times for both change and level detectors

We examine the form of distributions of simple reaction time. The stimuli we use are the offset of weak pure tones masked by wide-band noise. The hazard functions of the RT distributions (i.e, the probability of a response given that one has not already occurred) are monotone increasing for very weak tones but become peaked for stronger tones. Of the models available in the literature, none is very satisfactory, although two can account for the general qualitative shape of the peaked hazard functions. We propose a model wherein both a change and a level detector function in parallel. If one assumes that the change detector and level detector have slightly different thresholds, this model can account for both the monotone increasing and the peaked hazard functions.