The aftereffects of ventriloquism: the time course of the visual recalibration of auditory localization.

Exposure to synchronous but spatially discordant auditory and visual inputs produces adaptive recalibration of the respective localization processes, which manifest themselves in measurable aftereffects. Here we report two experiments that examined the time course of visual recalibration of apparent sound location in order to establish the build-up and dissipation of recalibration. In Experiment 1 participants performed a sound localization task before and during exposure to an auditory-visual discrepancy. In Experiment 2, participants performed a sound localization task before and after 60, 180 or 300 exposures to the discrepancy and aftereffects were measured across a series of post-adaptation sound localization trials. The results show that recalibration is very fast. Substantial aftereffects are obtained after only 18-24 exposures and asymptote appears to be reached between 60 and 180 exposures. The rate of adaptation was independent of the size of the discrepancy. The retention of the aftereffect was strong, as we found no dissipation, not even after as few as 60 exposure trials.