Ventriloquism effect and aftereffect in the distance dimension

Abstract

When an auditory target is presented simultaneously with a spatially displaced visual target, the perceived auditory target location shifts toward the visual target. This effect, known as the ventriloquism effect or visual capture, has been extensively studied in the horizontal dimension, but not in distance. Here, we measured distance localization performance in a reverberant room. Stimuli were either audio-visual (AV) 300-ms broadband noise bursts presented synchronously with spatially congruent or incongurent visual stimuli/LEDs, or auditory-only (A-only) noise bursts. One of eight speakers (distance 70 cm to 203 cm directly ahead of the listener) presented a stimulus on each trial. During adaptation runs, the AV stimuli were presented with the V-component closer or further by 30% than the A-component (displacement direction fixed within session). The ventriloquism effect was observed for both V-closer and V-further AV stimuli, with slightly stronger shifts induced by the V-closer stimuli. Ventriloquism aftereffect, assessed by presenting A-only trials interleaved with the adaptation-AV trials, was also observed, but was weaker than the ventriloquism effect. The results suggest that visual targets do capture auditory targets in the distance dimension, but visual modulation might be asymmetrical with respect to distance. [Work supported by EU FP7-247543, VEGA-1/0492/12, NSF (BCS-1057625).]