Audiovisual integration in depth

Abstract

There are several reasons to believe that audiovisual integration might be affected by distance. Namely, the retinal image and the perceived intensity will decrease and arrival time of sound will be delayed. In addition, previous research has already pointed out that there exist different regions of 3D-space with respect to the processing of stimuli. We wondered if and in what manner distance affects audiovisual integration. In the present study audiovisual integration was investigated with a detection task at six different distances from 80 cm up to 15 meters. Response times, multisensory response enhancement, and race model violation were analyzed. It seemed that distance did not affect the amount of audiovisual integration, as there were no significant differences in race model inequality violation between the six distances. Our results did indicate a slight change in multisensory integration from peripersonal to extrapersonal space, by distinctive effects around the border of peripersonal space. In addition the far space conditions showed slightly different results then the near space conditions. Given that RTs for the unimodal stimuli were unequal at 80 cm distance and became more equal as distance increased, integration might be enlarged for the distances further away. This effect could have covered a decrease of integration over distance.