Does stimulus location influence a visual illusion induced by sound?
Poster Presentation

Kaisa Tiippana
Laboratory of Computational Engineering, Helsinki University of Technology

Mikko Sams
Laboratory of Computational Engineering, Helsinki University of Technology

     Abstract ID Number: 89
     Full text: Not available
     Last modified: March 21, 2005

Abstract
Multisensory interactions are generally stronger when stimulation arises from a similar location in space. This study investigated the effect of stimulus side on an audiovisual illusion in which a single flash is often perceived as two when accompanied by two rapid beeps (Shams & al, 2002, Cogn Brain Res 14, 147-152). 1-3 flashes and beeps were presented to the left or right side of fixation either alone or together in a factorial design. The latter presentations could be either congruent so that both auditory and visual stimuli were on the same side, or incongruent so that the stimuli were presented on opposite sides of fixation. Subjects were instructed to count the flashes, and to ignore any beeps. The results replicated the illusion, and showed that the congruence of stimulus location did not affect subjects’ performance. The fact that audiovisual speech perception is not influenced by stimulus location (Jones & Munhall, 1997, Canad Acoust 25, 13-19), either, suggests that categorical perception may be much less sensitive to stimulus location than many other audiovisual tasks based on continuous perception of stimulus qualities.