Kinetic Attraction During Bimanual Coordination

Abstract

Two experiments examined the effects of independent variations in kinetic and kinematic requirements on interlimb coupling during a bimanual task. The goal of the investigation was to provide preliminary evidence regarding one general class of physical variables that constrains discrete bimanual movements. Subjects attempted to execute a smooth unidirectional movement with the left arm, along with a three-segment reversal movement with the right arm. The first experiment manipulated the torque required to produce the reversal action, while movement duration and average angular velocity were held constant for both limbs. Several indications of increased interlimb coupling, due to the kinetic variation, were evident. The converse manipulation was used in the second experiment, with movement time and kinematics (velocity, acceleration) changed independently of joint torque requirements for the reversal limb. No clear effect of kinematics on coupling strength was noted. The results suggest that one variable influencing interlimb attraction toward common spatiotemporal trajectories may be kinetic in nature.

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Notes on contributors

Charles B. Walter

The authors extend their sincere appreciation for the thoughtful comments of Les Carlton, Daniel Corcos, and Mark Latash on an earlier draft of this manuscript. Thanks are also extended for the extremely useful suggestions of the two reviewers. This work was supported by funding from the BRSG program of the National Institute of Health to the first author and through Collaborative Research Grant #86/732 from the NATO Scientific Affairs Division to the second author. Please address all correspondence to Charles B. Walter, Motor Control Laboratory MIC 194, Department of Physical Education, University of Illinois at Chicago, P.O.B. 4348, Chicago, IL 60680.