Sounds can alter the perceived direction of a moving visual object

Auditory temporal or semantic information often modulates visual motion events. However, the effects of auditory spatial information on visual motion perception were reported to be absent or of smaller size at perceptual level. This could be caused by a superiority of vision over hearing in reliability of motion information. Here, we manipulated the retinal eccentricity of visual motion and challenged the previous findings. Visual apparent motion stimuli were presented in conjunction with a sound delivered alternately from two horizontally or vertically aligned loudspeakers; the direction of visual apparent motion was always perpendicular to the direction in which the sound alternated. We found that the perceived direction of visual motion could be consistent with the direction in which the sound alternated or lay between this direction and that of actual visual motion. The deviation of the perceived direction of motion from the actual direction was more likely to occur at larger retinal eccentricities. These findings suggest that the auditory and visual modalities can mutually influence one another in motion processing so that the brain obtains the best estimates of external events.