Production of polyrhythms.

Previous research has shown that there are strong constraints on the concurrent performance of nonharmonically related motor sequences such as polyrhythms. A model of polyrhythm production is proposed that involves a hierarchical timing system. The model assumes a single mechanism (a counter) for the timing and serial ordering of responses. Predictions derived from the model were tested in an experiment in which skilled (musically trained) and unskilled Ss attempted to reproduce polyrhythms of varying complexity. The results agreed with the model's predictions and showed that Ss adopted a hierarchical form of integrated motor organization in which movements of the slow hand were subordinate to movements of the fast hand. This strategy was consistent across S groups, polyrhythms, and hand arrangements.