Motion-Binding Property Contributes to Accurate Temporal-Order Perception in Audiovisual Synchrony.

Temporal perception in multisensory processing is important for an accurate and efficient understanding of the physical world. In general, it is executed in a dynamic environment in our daily lives. In particular, the motion-binding property is important for correctly identifying moving objects in the external environment. However, how this property affects multisensory temporal perception remains unclear. We investigate whether the motion-binding property influences audiovisual temporal integration. The study subjects performed four types of temporal-order judgment (TOJ) task experiments using three types of perception. In Experiment 1, the subjects conducted audiovisual TOJ tasks in the motion-binding condition, between two flashes, and in the simultaneous condition, in which the two flashes are perceived as simultaneous stimuli without motion. In Experiment 2, subjects conducted audiovisual TOJ tasks in the motion-binding condition and the short and long successive interval condition, in which the two stimuli are perceived as successive with no motion. The results revealed that the point of subjective simultaneity (PSS) and the just-noticeable difference (JND) in the motion-binding condition differed significantly from those in the simultaneous and short and long successive interval conditions. Specifically, the PSS in the motion-binding condition was shifted toward a sound-lead stimulus in which the PSS became closer to zero (i.e., physical simultaneity) and the JND became narrower compared to other conditions. This suggests that the motion-binding property contributes to accurate temporal integration in multisensory processing by precisely encoding the temporal order of the physical stimuli.