The fast and the slow of skilled bimanual rhythm production: Parallel versus integrated timing

Professional pianists performed 2 bimanual rhythms at a wide range of different tempos. The polyrhythmic task required the combination of 2 isochronous sequences (3against 4) between the hands; in the syncopated rhythm task successive keystrokes formed intervals of identical (isochronous) durations. At slower tempos, pianists relied on integrated timing control merging successive intervals between the hands into a common reference frame. A timer-motor model is proposed based on the concepts of rate fluctuation and the distinction between target specification and timekeeper xecution processes as a quantitative account of performance atslow tempos. At rapid rates expert pianists used hand-independent, parallel timing control. In alternative to a model based on a single central clock, findings upport a model of flexible control structures with multiple timekeepers that can work in parallel to accommodate specific task constraints. Polyrhythms have received considerable attention in the study of bimanual coordination because they require the simultaneous production of conflicting (non-harmonically-related) motor sequences, like three beats in the left han