Previous behavioural studies have challenged the notion of unrestricted visual dominance in motion perception by demonstrating that the auditory modality can affect visual motion perception in the peripheral field. Thus far, electrophysiological evidence for the interplay between both modalities across space has not been provided, yet. The present study investigated crossmodal interactions during the encoding of bimodal motion offsets at different locations in space. To this end, moving audio-visual stimuli with either congruent or spatially and temporally disparate motion offsets were presented along different azimuthal trajectories in free-field while event-related potentials (ERPs) were recorded.
The pattern of interactions at motion offset suggests that dominance effects between modalities are reflected in a latency shift of ERP components. The latencies of the visual offset N1 were shifted towards the respective termination of the moving acoustic signal at peripheral motion offset locations. The presence of a concurrent visual motion stream less consistently affected the latencies of auditory offset components at frontal motion offset locations which only partially supports the widely reported visual dominance in the central visual field. However, the results provide electrophysiological evidence that the auditory system can modulate the processing of motion streams in the peripheral visual field which is supposed to be due to superior tracking of an ongoing motion in the periphery by the auditory system compared to the visual system. Our findings are well in line with previous studies that highlighted the crucial role of the auditory modality when the reliability of the visual signal is degraded.