Sensory uncertainty modulates audio-visual interactions.
Poster

James Heron
Department of Optometry, University of Bradford, UK

D. Whitaker
Department of Optometry, University of Bradford, UK

Paul V. McGraw
Department of Optometry, University of Bradford, UK

     Abstract ID Number: 74
     Full text: Not available
     Last modified: May 22, 2003

Abstract
Auditory signals have been shown to have a marked influence on visual perception in a wide range of tasks. However, the mechanisms of these interactions are, at present, poorly understood. Here we present a series of experiments where a temporal cue in the auditory domain (gaussian white noise) can significantly affect the localisation of a visual target (luminance defined gaussian blob). Positional tasks such as these were previously thought to be relatively impervious to auditory influences.

To investigate the mechanism of this interaction, we first modulated the positional uncertainty by increasing the size of visual targets. When positional uncertainty was low (small target size), auditory signals had little or no influence on perceived visual position. However, with increasing visual uncertainty (larger target size) auditory signals exerted a significantly larger influence on perceived visual position. We then altered the temporal profile of the auditory signal by modulating its temporal gaussian envelope. Introducing this temporal uncertainty to the auditory signal greatly reduced the susceptibility of visual localization to auditory influences, and perceived position became more veridical. Thus it would appear that the level of uncertainty in individual sensory domains appears to govern the perceptual outcome of multisensory integration.

Acknowledgments: PV McGraw is supported by The Wellcome Trust.