Auditory-visual sensory integration lowers visual detection thresholds and raises discrimination thresholds
Poster Presentation

Philip Jaekl
Psychology, York University

Laurence Harris
Psychology and Biology, York University

     Abstract ID Number: 50
     Full text: Not available
     Last modified: June 11, 2007
     Presentation date: 07/06/2007 10:00 AM in Quad Maclauren Hall
     (View Schedule)

Abstract
Auditory-visual sensory integration causes visual enhancement in a luminance detection task (Stein et al., 1996) which may result, in part, from changes in parvocellular activity. Facilitation was assessed using a detection task and a discrimination task in which sounds were presented before, synchronized with and after visual targets. The QUEST adaptive method was used in both conditions. Detection condition: a two-alternative forced choice (2afc) metacontrast masking task with a circular visual target followed by an annular mask. Sound-target synchrony resulted in lower luminance thresholds for detecting the presence of a target compared to when no sound occurred, or when sound onset preceded target onset. Thresholds were also lowered when the sound was synchronous with the mask at target-mask interstimulus intervals < 50ms. Discrimination condition: a 2afc orientation task requiring participants to discriminate a vertically oriented Gabor patch from a tilted one. Threshold angles for discriminating Gabor patch orientations increased in the presence of a sound at all sound-target onset asynchronies and were highest when sound onset followed target onset. These results are compatible with a sound-induced activity increase in the parvocellular visual pathway. This study demonstrates psychophysically that auditory-visual integration affects simple visual stimulus detection and stimulus feature discrimination differently.