Temporal ventriloquism: crossmodal interaction on the time dimension - 2. Evidence from sensorimotor synchronization

In two experiments, we measured audio-visual crossmodal attraction on the time dimension, using a sensorimotor synchronization task. Synchronization performance made it possible to split up the total crossmodal attraction (demonstrated in earlier studies through inter-modal temporal order judgments) into its modality-specific components, the auditory bias of the visual event's perceived time of occurrence and the visual bias of the auditory event's perceived time of occurrence. Participants were asked to produce tapping movements in synchrony with a sequence of isochronously repeated pacing signals. In Experiment 1, pacing signals were light flashes, each preceded or followed, at one of several stimulus onset asynchronies (SOAs), by an auditory distracter that the participant was instructed to ignore. The timing of the tap was, in spite of that instruction, strongly biased toward the distracter. In Experiment 2, the converse task was used. The pacing signals were auditory and the to be ignored distracters, light flashes. The timing of the taps was biased significantly here also toward the distracter, but to a much lesser extent. Taken together, these results clearly demonstrate that audition plays a bigger role than vision in temporal ventriloquism and is probably generally superior to vision for processing the temporal dimension of events. (C) 2003 Elsevier Science B.V. All rights reserved.