Social interaction and rate effects in models of musical synchronization

Important individual differences are observed in peoples abilities to synchronize their body movements with regular auditory rhythms. We investigate whether synchronizing with a regular auditory cue is affected by each persons spontaneous production rate (SPR) and by hearing a partners synchronization in a social context. Musically trained and untrained participants synchronized their tapping with an auditory cue presented at different rates (their own SPR or their partners SPR) and in a Solo or Joint (turn-taking) condition. Linear and nonlinear oscillator models were fit to participants mean asynchronies (signed timing differences between the cued onsets and taps). In Joint turn-taking, participants synchrony was increased when the auditory signal was cued at the participants own SPR, compared with their partners SPR; in contrast, synchronization did not differ across rates in the Solo condition. Asynchronies in the Joint task became larger as the difference between partners spontaneous rates increased; the increased asynchronies were driven by the faster partner who did not slow down to match the rate of their slower partner. Nonlinear delay-coupled models (with time delay, coupling strength, and intrinsic frequency) outperformed linear models (intrinsic frequency only) in accounting for tappers synchronization adjustments. The nonlinear models coupling value increased for musically trained participants, relative to untrained participants. Overall, these findings suggest that both intrinsic differences in partners spontaneous rates and the social turn-taking context contribute to the range of synchrony in the general population. Delay-coupled models are capable of capturing the wide range of individual differences in auditory-motor synchronization.