On intersensory evoked potentials

It has been found in a variety of studies that, for human observers, reaction time is faster to a sound than to a light. The study being reported here was designed to test the hypothesis of audio-visual facilitation when a flash precedes a sound by about 30 to 50 milliseconds. It is hypothesized that the electrophysiological result of this facilitation will be an increased energy of the event related potential (ERP) resulting from the interaction between the visual and auditory processes. The stimuli consisted of a click (A), a flash (V), a simultaneous flash-click (AV), a flash preceding the click by 40 milliseconds (AV40) and by 80 milliseconds (AV 80). All of the stimuli were presented to the subject at random. Comparison of the ERP averages for the five subjects tested, and for the above mentioned conditions, supported the hypothesis of sensory integration. The AV40 averages indicated a larger recruitment of cells, as evidenced by a larger response than the AV, A, or V responses separately.