Bimodal and trimodal multisensory enhancement: effects of stimulus onset and intensity on reaction time. Percept Psychophys 66

Manual reaction times to visual, auditory, and tactile stimuli presented simulta-neously, or with a delay, were measured to test for multisensory interaction effects in a simple detection task with redundant signals. Responses to trimodal stimulus combinations were faster than to bimodal combinations, which in turn were faster than reactions to unimodal stimuli. Response enhancement increased with decreas-ing auditory and tactile stimulus intensity and was a u-shaped function of stimulus onset asynchrony. Distribution inequality tests indicated that the multisensory in-teraction effects were larger than predicted by separate activation models, including the difference between bimodal and trimodal response facilitation. The results are discussed with respect to previous findings in a focused attention task and are com-pared to multisensory integration rules observed in bimodal and trimodal superior colliculus neurons in the cat and monkey. Diederich & Colonius: Trimodal Interaction