Implicit auditory modulation on the temporal characteristics of perceptual alternation in visual competition.

Visual competition refers to the spontaneous change of the subjective perception of ambiguous visual patterns. We investigated how implicit and explicit auditory inputs affect the temporal characteristics of perceptual alternation and the interpretation bias in ambiguous visual patterns. Participants traced the perceived direction of apparent visual motion, while two task-irrelevant auditory tones were alternately presented. In the pre- and post-learning sessions, ambiguous apparent motion (seen as moving vertically or horizontally) was presented. In the learning session, disambiguated vertical and horizontal apparent motions were alternately presented and switched in synchronization with the changes in auditory tones. The results showed that the temporal intervals of perceptual alternation from the auditory switches were reduced after the participants experienced the synchronized audiovisual switches, even when the auditory switches were not consciously detectable. The magnitude of the effect was comparable for the implicit and explicit auditory switches. Neither explicit nor implicit auditory tones biased the interpretation of the ambiguous visual motion. These results suggest that auditory inputs implicitly affect the temporal characteristics of perceptual alternation after participants experience synchronized audiovisual events.