INTERSENSORY FACILITATION OF REACTION-TIME - EVALUATION OF COUNTER AND DIFFUSION COACTIVATION MODELS

In a simple reaction time experiment a subject's task is to react to stimuli from three different modalities (visual, auditory, tactile) when any of the stimuli is presented alone, as a pair from two different modalities, or as a triple from all three modalities. The shorter reaction time to double stimuli compared to reaction time to single stimuli or the shorter reaction time to triple stimuli compared to reaction time to double and single stimuli is called ''intersensory facilitation of reaction time.'' Two models were considered to explain this phenomenon: a counter model (Poisson superposition) and a diffusion model (Ornstein-Uhlenbeck process). Both models gave an excellent fit on the level of mean reaction times. (C) 1995 Academic Press, Inc.