The Effect of Auditory Stream Segregation on Synchronized Tapping

Abstract

We can tap in synchrony with a simple sequence of auditory tones, but our taps generally precede it by several tens of milliseconds("negative mean asynchrony"). A simple sequence of sounds sometimes causes auditory perceptual organization different from the physical sequence. However little is known about interactions between the auditory perceptual organization and sensorimotor synchronization. The present study aimed at investigating effects of the auditory stream segregation (one stream or two) on the synchronized tapping. Participants listened to a sequence of two different auditory tones presented alternately, and were asked to tap in synchrony with one group of tones (ie, high tones or low) with index fingers. After that, they were also asked whether the tones were perceived one or two streams. The results showed that negative mean asynchrony was caused both in perceived one stream and two. However, the amplitude of the asynchrony was smaller when they perceived the tones as one stream than as two. This indicates that auditory perceptual organization affects sensorimotor synchronization even if auditory tones were presented with the same timing. When we synchronize bodily with auditory tones as in the case of a motor rehabilitation, we have to take account of auditory perceptual organization.