Visual motion perception induced by sounds in vertical plane.

The alternation of sounds in the left and right ears induces motion perception of a static visual stimulus (SIVM: Sound-Induced Visual Motion). In this case, binaural cues were of considerable benefit in perceiving locations and movements of the sounds. The present study investigated how a spectral cue - another important cue for sound localization and motion perception - contributed to the SIVM. In experiments, two alternating sound sources aligned in the vertical plane were presented, synchronized with a static visual stimulus. We found that the proportion of the SIVM and the magnitude of the perceived movements of the static visual stimulus increased with an increase of retinal eccentricity (1.875-30 degree), indicating the influence of the spectral cue on the SIVM. These findings suggest that the SIVM can be generalized to the whole two dimensional audio-visual space, and strongly imply that there are common neural substrates for auditory and visual motion perception in the brain.