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California State University, Long Beach
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April Witty

May 1994

The Effects of Duration, Interstimulus Onset Interval (ISOI) and Separation on Perceived Velocity in Auditory Apparent Motion


    Auditory apparent motion is an illusion produced by the proper timing and placement of two discrete stimuli; under optimal conditions movement of the lead stimulus toward the lag stimulus is perceived.  This study investigated the effect of duration, ISOI and separation on subjects’ ability to perceive velocity in auditory apparent motion.  Eight subjects were exposed to 80 unique duration, ISOI and separation combinations and were asked to make velocity estimations.  All hypotheses were supported; as duration and ISOI increased, velocity estimations decreased and as separation increased, velocity estimations increased.

    Subjects were asked to make duration and separation estimations after they completed the velocity estimation task to make sure they were not judging duration or separation and interpreting it as velocity.  The results from the duration and separation estimation tasks did not parallel the results from the velocity estimation task.  The results suggest that temporal factors (stimulus duration and ISOI) have a greater influence than spatial factors on subjects’ perceived velocity judgments.