Could an auditory equivalent to a continuously varying visual stimulus improve beat synchronization? Evidence supporting vision as a trustworthy modality in sensorimotor timing.

Although synchronization to a perceived regular beat in time has been established to be much less variable for discrete auditory stimuli, such as tones, than for discrete visual stimuli, such as flashes, recent advances in beat synchronization research have demonstrated that visual beat synchronization can be substantially improved and become comparable to auditory tones when employing continuously moving visual stimuli. It therefore has been suggested that the difference in modality is an important but not necessarily dominant factor for beat synchronization. However, doubts exist in favoring auditory dominance, as comparing continuously varying visual stimuli with discrete auditory stimuli is considered unfair. Here, based on a periodically contracting ring for which the spatial displacement continuously varied with a constant acceleration, we devised an equivalent in the auditory domain: an amplitude-modulated sound whose amplitude continuously varied with an acceleration of the same magnitude. The results showed that beat synchronization performance of the amplitude-modulated sound was not greater than that of the tone or the contracting ring. The present finding supports that vision is a trustworthy modality for sensorimotor timing processing.