When sound affects vision: Effects of auditory grouping on visual motion perception

Two identical visual targets moving across each other can be perceived eith er to bounce off or to stream through each other. A brief sound at the mome nt the targets coincide biases perception toward bouncing. We found that th is bounce-inducing effect was attenuated when other identical sounds (audit ory flankers) were presented 300 ms before and after the simultaneous sound . The attenuation occurred only when the simultaneous sound and auditory fl ankers had similar acoustic characteristics and the simultaneous sound was not salient. These results suggest that there is an aspect of auditory-grou ping (saliency-assigning) processes that is context-sensitive and can be ut ilized by the visual system for solving ambiguity. Furthermore, control exp eriments revealed that such auditory context did not affect the perceptual qualities of the simultaneous sound. Because the attenuation effect is not manifest in the perception of acoustic characteristics of individual sound elements, we conclude that it is a genuine cross-modal effect.