COOPERATIVE SELECTION OF MOVEMENTS - THE OPTIMAL SELECTION MODEL

How one selects a movement when faced with alternative ways of doing a task is a central problem in human motor control. Moving the fingerti p a short distance can be achieved with any of an infinite number of c ombinations of knuckle, wrist, elbow, shoulder, and hip movements. The question therefore arises: how is a unique combination chosen? In our model, choice is achieved by consideration of the similarity between the task requirements and the optimal biomechanical performance of eac h limb segment. Two variants of the model account for the movements th at are selected when subjects freely oscillate the fingertip and when they tap against an obstacle. An important feature of both is that the impulse of collision with an obstacle (as in drumming with the hand o r tapping with the finger) is assumed to be controlled in part by aimi ng for a point beyond the surface being struck. Thus, a force-related control variable may be represented and controlled spatially.