Why movement is captured by music, but less by speech: role of temporal regularity.

Music has a pervasive tendency to rhythmically engage our body. In contrast, synchronization with speech is rare. Music's superiority over speech in driving movement probably results from isochrony of musical beats, as opposed to irregular speech stresses. Moreover, the presence of regular patterns of embedded periodicities (i.e., meter) may be critical in making music particularly conducive to movement. We investigated these possibilities by asking participants to synchronize with isochronous auditory stimuli (target), while music and speech distractors were presented at one of various phase relationships with respect to the target. In Exp. 1, familiar musical excerpts and fragments of children poetry were used as distractors. The stimuli were manipulated in terms of beat/stress isochrony and average pitch to achieve maximum comparability. In Exp. 2, the distractors were well-known songs performed with lyrics, on a reiterated syllable, and spoken lyrics, all having the same meter. Music perturbed synchronization with the target stimuli more than speech fragments. However, music superiority over speech disappeared when distractors shared isochrony and the same meter. Music's peculiar and regular temporal structure is likely to be the main factor fostering tight coupling between sound and movement.