Perceptual training of audiovisual simultaneity judgments generalizes across spatial locations.

Multisensory processing critically depends on the perceived timing of stimuli in the different sensory modalities. Crossmodal stimuli that fall within rather than outside an individual temporal binding window (TBW) are more likely to be bound into a multisensory percept. A number of studies have shown that a short perceptual training in which participants receive feedback on their responses in an audiovisual simultaneity judgment (SJ) task can substantially decrease the size of the TBW and hence increase crossmodal temporal acuity. Here we tested whether multisensory perceptual learning in the SJ task is specific for the spatial locations at which the audiovisual stimuli are presented during training. Participants received feedback about the correctness of their SJ responses for audiovisual stimuli which were presented in one hemifield only. The TBW was assessed separately for audiovisual stimuli in each hemifield before and one day after the training. In line with previous findings, the size of the TBW was significantly reduced after the training phase. Importantly, an equally strong reduction of TBW size was observed in both the trained and the untrained hemifield. Thus, multisensory temporal learning completely generalized to the untrained hemifield, suggesting that the improvement in crossmodal temporal acuity was mediated by higher, location-invariant processing stages. These findings have implications for the design of multisensory training protocols in applied settings such as clinical interventions by showing that training at multiple spatial locations might not be necessary to achieve robust improvements in crossmodal temporal acuity.