Sound delay in audiovisual events can signal object depth
43.518, Monday, May 13, 8:30 am - 12:30 pm, Vista Ballroom
Philip Jaekl1, Jakob Maxwell Seidlitz1, Duje Tadin1,2; 1Center for Visual Science & Dept. of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, USA 14627, 2Department of Ophthalmology, University of Rochester, Rochester, NY, USA 14627
The slower arrival time of sound relative to light varies linearly with the distance of an audiovisual event and can potentially be used as reliable cue to depth. Here, we aimed to determine if sound delay in audiovisual events can influence visual judgments of distance. We hypothesized that a given visual event paired with delayed sound would be perceived as being further away than when paired with synchronous sound. Using a 2IFC task, participants judged the distance of two stereoscopically presented random dot clouds in a fixed 3D volume (250ms duration, 1-1.5 ms ISI). In one interval the cloud was paired with a synchronous sound, while in the other, the sound was delayed by 80 ms relative to the visual stimulus onset. By varying the disparity of the dots, the 'cloud' presented in the second interval was stereoscopically shifted either toward or away from the participant relative to the first cloud. Task difficulty was controlled by the percentage of dots that coherently shifted in depth, ranging from 0% (random dispersion of dots) to 100% (fully coherent shift). When the delayed sound was presented in the second interval, participants showed a bias towards perceiving the stimuli as shifting away from the observer. The opposite pattern occurred when the delayed sound occurred in the first interval. By comparing congruent and incongruent audio-visual pairings, we found a trend for participants to be more precise when sound delays were congruent, with the direction of the visual depth shift. These findings reveal that sound delay in audiovisual events can be used when making distance judgmentsa task previously thought to be solved only visually. Evidently, sound delays modulate visual depth perception and possibly provide a previously unknown depth cue.