Synchronizing to auditory and tactile metronomes: a test of the auditory-motor enhancement hypothesis.

Humans show a striking advantage for synchronizing movements with discretely timed auditory metronomes (e.g., clicking sounds) over temporally matched visual metronomes (e.g., flashing lights), suggesting enhanced auditory-motor coupling for rhythmic processing. Does the auditory advantage persist for other modalities (not just vision)? Here, nonmusicians finger tapped to the beat of auditory, tactile, and bimodal metronomes. Stimulus magnitude and rhythmic complexity were also manipulated. In conditions involving a large area of stimulation and simple rhythmic sequences, tactile synchronization closely matched auditory. Although this finding shows a limitation to the hypothesis of enhanced auditory-motor coupling for rhythmic processing, other findings clearly support it. First, there was a robust advantage with auditory information for synchronization with complex rhythm sequences; moreover, in complex sequences a measure of error correction was found only when auditory information was present. Second, higher order grouping was evident only when auditory information was present.