Abstract
If visual and audio stimuli are repeatedly presented with a certain constant temporal asynchrony for a few minutes, the perceived temporal asynchrony between the stimuli would be reduced. This phenomenon called as “audio-visual temporal recalibration”. Many previous studies have shown that the temporal recalibration could be obtained with short stimuli (up to 20 ms). Therefore, they have not found whether temporal recalibration may occur for both onset and offset of a long audio-visual stimuli, and whether a constant temporal gap between the onset (or offset) of the audio-visual stimuli would enable the recalibration for the offset (or onset) of the stimuli. The present study focused on these issues. We used a white noise as an audio stimulus and a white circle as a visual stimulus (longer than 200 ms) for which participants easily separated their onset and offset. Experiments consisted of adaptation phase and test phases. In the adaptation phase, the auditory-visual stimuli with a constant temporal asynchrony (-240, 0 or +240 ms) were presented for about 3 minutes. In the test phase, participants judged which of the visual stimulus or auditory stimulus is the first. On the one hand, if participants were exposed to the asynchrony between the onsets of the audio-visual stimuli (or between their offsets) and tested for the temporal order of their onsets (or their offsets), we found stable audio-visual recalibration. On the other hand, if participants were exposed to the asynchrony between the onsets of the stimuli (or between their offsets) and tested for the temporal order of their offsets (or their onsets), we found no substantial audio-visual recalibration. These results suggest that the audio-visual temporal recalibration is restricted to the temporal features of the stimuli which were exposed with a constant temporal asynchrony.