Auditory motion in depth is preferentially 'captured' by visual looming signals.

The phenomenon of crossmodal dynamic visual capture occurs when the direction of motion of a visual cue causes a weakening or reversal of the perceived direction of motion of a concurrently presented auditory stimulus. It is known that there is a perceptual bias towards looming compared to receding stimuli, and faster bimodal reaction times have recently been observed for looming cues compared to receding cues (Cappe et al., 2009). The current studies aimed to test whether visual looming cues are associated with greater dynamic capture of auditory motion in depth compared to receding signals. Participants judged the direction of an auditory motion cue presented with a visual looming cue (expanding disk), a visual receding cue (contracting disk), or visual stationary cue (static disk). Visual cues were presented either simultaneously with the auditory cue, or after 500 ms. We found increased levels of interference with looming visual cues compared to receding visual cues, compared to asynchronous presentation or stationary visual cues. The results could not be explained by the weaker subjective strength of the receding auditory stimulus, as in Experiment 2 the looming and receding auditory cues were matched for perceived strength. These results show that dynamic visual capture of auditory motion in the depth plane is modulated by an adaptive bias for looming compared to receding visual cues.