Toward a movement dynamics perspective on dual-task performance.

The effect of practice on the parallel organization and control of discrete, asymmetrical bimanual movements was investigated. Subjects performed a flexion movement in the left limb together with a flexion-extension-flexion movement in the right limb. Two groups, one of which received kinematic information feedback, were instructed to produce the different patterns simultaneously. A third group performed each movement in isolation at all times, serving as the baseline condition. The degree of success in parallel action organization was assessed at the qualitative (or structural) and quantitative (or metrical) level of movement specification. Findings revealed that the bimanual groups displayed a tendency to synchronize the patterns of motor output, resulting in (mutual) interference. However,the provision of augmented kinematic information feedback resulted in more successful metrical and structural dissociation of the limb actions. The results are discussed in support of a movement dynamics perspective on motoric dual-task performance. The relevance of the approach for human factors is also emphasized.