Phase adjustment of rhythmic auditory and visual streams
Poster Presentation

Ben Schouten
University of Leuven, Belgium

Karl Verfaillie
University of Leuven, Belgium

     Abstract ID Number: 100
     Full text: Not available
     Last modified: June 18, 2007
     Presentation date: 07/06/2007 10:00 AM in Quad Maclauren Hall
     (View Schedule)

Abstract
Using audiovisual sequences of biological and artificial stimuli at various rhythms, Arrighi, Alais and Burr (2006) recently showed that the auditory stream needs to be delayed for sight and sound to be perceived simultaneously. More importantly, they showed that the size of the auditory delay inversely depends on the tempo of the rhythm. We replicated their findings with comparable stimuli (both biological and artificial motion) but with a different methodology (phase adjustment). The artifical motion stimulus was a horizontally back and forth translating Gaussian blob at different speeds. The biological motion stimulus consisted of a point-light walker walking at different speeds. On each trial the visual motion stimulus was accompanied by auditory rhythmic ticks with the same rhythm but with a random phase shift relative to the visual motion pattern. In two experiments participants had to adjust the auditory rhythmic ticks to the change in direction of the blob (Exp 1) or to the footsteps of the point-light walker (Exp 2). Estimated points of subjective simultaneity in both experiments pointed to the necessity of an auditory delay, inversely varying with the tempo of the rhythm, to perceive the audiovisual stimuli as simultaneous.