Cite as:
McCourt M E, Pasieka B, 2003, "Auditory 'capture' of visual motion" Perception 32 ECVP Abstract Supplement

Auditory 'capture' of visual motion

M E McCourt, B Pasieka

Visual perception is significantly altered by auditory stimuli. We asked whether the perceived direction of visual motion could be influenced by auditory signals. The visual stimulus was a spatiotemporally vignetted sine-wave grating. Multiple 'frames' of this stimulus were combined into short movies. Each frame lasted 125 ms, and each movie consisted of 3 frames. Between successive frames, the spatial phase of the grating was altered. Nine phases were sampled, ranging from 90° to 270° in increments of 18°. An interframe phase shift of 180° produced a movie in which the direction of grating drift was ambiguous and bistable. Interframe phase shifts of 90° or 270° produced unambiguous apparent motion. We paired the presentation of the movies with auditory stimuli. The auditory stimulus was a binaural amplitude-gated burst of pink noise. In the rightward sound condition, the sound-source onset at a point 2 virtual metres to the left of the subject's head and moved at a constant velocity to a location 2 virtual metres to the right of the head. The opposite occurred in the leftward sound condition. There was also a no-sound control condition. Observers ignored the auditory stimulus and judged the direction of visual motion. The perceived direction of visual motion was strongly influenced by the direction of concurrent auditory motion. Auditory motion not only 'captured' ambiguous visual motion, but could even reverse the perceived direction of unambiguous visual motion. These results suggest that visual motion, a dynamic and spatiotemporal aspect of visual perception, can be altered by sound. Additional experiments exploring whether the influence of auditory motion on visual motion extends to the facilitation of motion discrimination thresholds are presented.

[Supported by the US National Science Foundation; EPS 0132289.]

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