The influence of visual cues on the localisation of circular auditory motion

A relative inability of listeners to refer auditory motion properly to the front hemifield when a rapid circular trajectory is traced around them in the horizontal plane was investigated. It was hypothesised that the representations of visual space and auditory frontal space are linked in such a way that auditory cues alone are insufficient to determine the veridical path in the front hemifield when both the front and the rear hemifield receive circular auditory input in rapid sequence. Listeners discriminated the direction of a rapid apparent trajectory created by the sequential activation of various combinations of loudspeakers and light-emitting diodes spaced evenly in a circular array. The addition of visual stimuli to the front hemifield, even when lacking motional cues, improved discrimination significantly. Conversely, when the same portion of the trajectory presented to the front hemifield consisted only of visual stimuli, performance decreased markedly. Additional conditions, in which the trajectory was restricted to a 120 deg path in the frontal plane, confirmed these effects. The findings suggest that the presence of a visual cue enhances the perception of auditory directionality, even when it does not itself provide any motion information.