The influence of speed and force on bimanual finger tapping patterns.

The current study investigated factors that affect the stability of anti-phase bimanual finger tapping. Past research employing the order parameter and control parameter concepts, has identified frequency of movement as a control parameter that affects the stability of finger movement patterns (the order parameter). The present study investigated the hypothesis that multiple movement related variables can interact to influence the stability of an order parameter. Specifically, the combined effect of the rate of movement and movement force on the stability of bimanual finger tapping was examined. Participants were required to initiate an anti-phase tapping pattern under three different movement rate conditions (600, 400, and 200 ms), and were required to increase the force of one finger at the onset of a randomly presented stimulus. The results indicate that an increase in the force parameter at lower tapping rates (600 ms) did not affect the phase relation of the fingers, however at higher rates (200 and 400 ms), the introduction of a force parameter resulted in fluctuations of the phase relation of the fingers, which were followed by pattern shifts from anti-phase to in-phase tapping. The results indicate that movement force and rate of movement interact to influence the outcome of the tapping pattern. Further research is required to investigate force as a control parameter.