The effects of stimulus strength on the timing of audiovisual multisensory facilitation(Spatio-temporal integration of multimodal sensations,Symposium 2 at the 27th Annual Meeting)

抄録

Four experiments examined temporal properties of audiovisual multisensory integration. Experiment 1 measured reaction time to 100ms auditory (A) and visual (V) stimuli, and to audiovisual (AV) combinations with stimulus onset asynchronies (SOAs) ranging from -100 to +200ms. Significant violations of Miller's inequality (signifying neural coactivation) occurred only for simultaneous presentation (AV SOA=0ms). Experiments 2 and 3 were identical to Experiment 1 with the following exceptions. In Experiment 2 auditory stimulus intensity was adjusted to clamp performance in auditory-only trials at a d'=2, while visual stimulus contrast was clearly suprathreshold (d'>4). The results indicated that neural coactivation occurred over an expanded range of AV SOAs from -60 to 0ms. In Experiment 3 visual stimulus contrast was adjusted to clamp performance in visual-only trials at a d'=2, while auditory stimulus intensity was clearly suprathreshold (d'>4). Neural coactivation in this case also occurred over an expanded range of AV SOAs, from 0 to +60ms. In Experiment 4 the intensity of both A and V stimuli was adjusted to clamp performance in unisensory trials at a d'=2. As in Experiment 1, neural coactivation occurred only for simultaneous AV presentation (AV SOA=0ms). These results have implications for early multisensory processing, the role of attention, and the generality of the inverse effectiveness rule.