Visual-auditory interaction: Compensating for the slower speed of sound
Single Paper Presentation

Laurence Harris
Centre for Vision Research, York University

Agnieszka Kopinska
Centre for Vision Research, York University

     Abstract ID Number: 95
     Full text: Not available
     Last modified: May 20, 2003

Abstract
How can a bimodal stimulus be perceived as a single event when the sound and light likely arrive at the sense organs at different times due to sound travelling so much slower than light? Information carried by sound and light also takes different amounts of time to be processed by the end organs and to be transmitted to the cortex. Processing time also depends on factors such as intensity, dark adaptation and eccentricity. We varied the distance of visual and auditory targets from one to thirty two metres, varied light intensity using dark glasses, and compared foveal with peripheral viewing. We measured the temporal offsets of light-sound pairings judged as synchronous, and reaction times to lights and sounds alone and to the light-sound pairings. Despite large differences in reaction times that varied in a predictable way with stimulus parameters, the timing of light-sound pairings judged as simultaneous corresponded to the light and the sound leaving the source simultaneously. The differences between perception (judgements of synchronicity) and action (reaction times) reveal how visual and auditory information about single object is combined into a single percept.