Tracking simple and complex sequences.

We address issues of synchronization to rhythms of musical complexity. In two experiments, synchronization to simple and more complex rhythmic sequences was investigated. Experiment 1 examined responses to phase and tempo perturbations within simple, structurally isochronous sequences, presented at different base rates. Experiment 2 investigated responses to similar perturbations embedded within more complex, metrically structured sequences; participants were explicitly instructed to synchronize at different metrical levels (i.e., tap at different rates to the same rhythmic patterns) on different trials. We found evidence that (1) the intrinsic tapping frequency adapts in response to temporal perturbations in both simple (isochronous) and complex (metrically structured) rhythms, (2) people can synchronize with unpredictable, metrically structured rhythms at different metrical levels, with qualitatively different patterns of synchronization seen at higher versus lower levels of metrical structure, and (3) synchronization at each tapping level reflects information from other metrical levels. The latter finding provides evidence for a dynamic and flexible internal representation of the sequence's metrical structure.