Expectations about dynamic visual objects facilitates early sensory processing of congruent sounds

The perception of a moving object can lead to the expectation of its sound, yet little is known about how visual expectations influence auditory processing. We examined how visual perception of an object moving continuously across the visual field influences early auditory processing of a sound that occurred congruently or incongruently with the object's motion. In Experiment 1, electroencephalogram (EEG) activity was recorded from adults who passively viewed a ball that appeared either on the left or right boundary of a display and continuously traversed along the horizontal midline to make contact and elicit a bounce sound off the opposite boundary. Our main analysis focused on the auditory-evoked event-related potential. For audio-visual (AV) trials, a sound accompanied the visual input when the ball contacted the opposite boundary (AV-synchronous), or the sound occurred before contact (AV-asynchronous). We also included audio-only and visual-only trials. AV-synchronous sounds elicited an earlier and attenuated auditory response relative to AV-asynchronous or audio-only events. In Experiment 2, we examined the roles of expectancy and multisensory integration in influencing this response. In addition to the audio-only, AV-synchronous, and AV-asynchronous conditions, participants were shown a ball that became occluded prior to reaching the boundary of the display, but elicited an expected sound at the point of occluded collision. The auditory response during the AV-occluded condition resembled that of the AV-synchronous condition, suggesting that expectations induced by a moving object can influence early auditory processing. Broadly, the results suggest that dynamic visual stimuli can help generate expectations about the timing of sounds, which then facilitates the processing of auditory information that matches these expectations.