On the timing basis of bimanual coordination in discrete and continuous tasks

Motor events are behaviorally meaningful, discrete entities (e.g., key strokes) that are generated at some specific portion of an effector's movement trajectory. Bimanual coordination may be conceptualized with reference to such discrete motor events or with reference to continuous movement trajectories. Studies inspired by the former approach suggest that hand coordination is primarily achieved by assigning a coherent timing goal structure to the motor events produced by each hand. Studies conducted with the latter approach have shown that between-hand interdependence may also arise from the cross-coupling of the command signals that generate each hand's motion. Little is known, however, about the relationships between timing-level coordination and trajectory-level coordination of the hands. Some aspects of these relationships are analyzed using data from experiments that involved bimanual finger tapping and circle drawing at identical and different frequencies.