The control of goal-directed limb movements: Correcting errors in the trajectory

A number of recent models of limb control have attempted to explain speed-accuracy tradeoff in goal-directed movements on the basis of the characteristics of the muscular impulses that are specified prior to movement initiation. In contrast, studies from our laboratory have demonstrated that, even for very rapid aiming movements, the characteristics of the movement trajectory change with the availability of visual information about the position of the limb and the target during the movement. Moreover, when the movement of the limb is perturbed at movement initiation by an electromagnetic force, performers can rapidly adjust their aiming movements in order to hit the target if visual feedback is available. The performer can also rapidly adjust to unexpected changes in target size and amplitude. Visually based adjustments to the movement trajectory can be either discrete or continuous. (C) 1999 Elsevier Science B.V. All rights reserved.