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Zusammenfassung:
If the audio and visual stream in a movie are poorly aligned the discrepancy between the actors’ speech and lip movements are very disturbing in the beginning. However, after a short time the constant delay in one modality becomes barely noticeable. This phenomenon is termed temporal recalibration, that is, the adaptation of synchrony perception to multisensory asynchronies in the environment. Here, we investigate whether and how temporal recalibration may be achieved via adaptation of the response towards unisensory stimuli. To this aim, we exposed participants to three minutes of either -150, 0 or +150ms audiovisual asynchrony. Subsequently, we tested participants’ unisensory detection threshold, reaction time, and gap detection. We observe remarkable changes with auditory-only trials following visual-leading audiovisual exposure: increases in detection threshold (i.e., sensitivity is lower), faster reactions, and improved gap detection performance. We do not find effects of adaptation using visual stimuli. These findings indicate that asynchronous exposure leads to changes in the neural response to unisensory stimuli. We suggest that such changes are the precursors of temporal recalibration: For the delayed stimulus during exposure accumulation of sensory evidence becomes higher early after stimulus onset, which, in accordance with a negative feedback mechanism, has the cost of an overall lowering of activation compared to the stimulus leading during exposure.
