Auditory grouping occurs prior to intersensory pairing: evidence from temporal ventriloquism

Abstract

The authors examined how principles of auditory grouping relate to intersensory pairing. Two sounds that normally enhance sensitivity on a visual temporal order judgement task (i.e. temporal ventriloquism) were embedded in a sequence of flanker sounds which either had the same or different frequency (Exp. 1), rhythm (Exp. 2), or location (Exp. 3). In all experiments, we found that temporal ventriloquism only occurred when the two capture sounds differed from the flankers, demonstrating that grouping of the sounds in the auditory stream took priority over intersensory pairing. By combining principles of auditory grouping with intersensory pairing, we demonstrate that capture sounds were, counter-intuitively, more effective when their locations differed from that of the lights rather than when they came from the same position as the lights.

Fig. 1

a A schematic illustration of a trial. Lights were presented with a particular SOA ranging between −75 and 75 ms, with negative values indicating that the lower light was presented first. Two capture sounds were presented either simultaneously with the lights (∼0 ms AV-interval), or ∼100 ms before the first and ∼100 ms after the second light (∼100 ms AV-interval). The capture sounds were embedded in a sequence of flanker sounds which either had the same or a different frequency (Exp1), rhythm (Exp 2), or location (Exp 3). Perceptual grouping of the sounds is illustrated by the grey ovals. Temporal ventriloquism only occurred when the capture sounds were different from the flanker sounds at the ∼100 ms interval, as illustrated on the second line. b Schematic set-up of Experiment 1, 2 and 3