Cognitive and biomechanical influences in pianists' finger tapping.

Movement sequences such as typing or tapping display important interactions among finger movements arising from anticipatory motion (preparing for upcoming events) and coupling (non-independence among fingers). We examined pianists' finger tapping for the influence of cognitive chunking processes and biomechanical coupling constraints. In a synchronization-continuation task, pianists repeatedly tapped four-finger sequences that differed in terms of the chunks that formed subsequences and in the transitions among physically adjacent or non-adjacent fingers. Chunking influenced intertap intervals, regardless of the particular fingers tapped; the final tap of each chunk was lengthened and less variable relative to other taps. The particular fingers tapped influenced peak finger heights, consistency of motion, and velocity-acceleration patterns, regardless of chunking. Thus, cognitive constraints influenced timing, whereas biomechanical factors influenced motion trajectories. These findings provide an important caveat for study of anticipatory motion by documenting the influence of biomechanical coupling on motion trajectories.