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 diffe rent tempos. The polyrhythmic task required the combination of 2 isochronou s sequences (3 against 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 su ccessive 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 execution processes as a quantitative account of performance at slow tempos. At rapid rates ex pert pianists used hand-independent, parallel timing control. In alternativ e to a model based on a single central clock, findings support a model of f lexible control structures with multiple timekeepers that can work in paral lel to accommodate specific task constraints.