ABSTRACT
Alterations in movement control across practice and the influence of augmented information feedback—knowledge of results (KR)—represent two fundamental concerns in skill acquisition research. In this chapter, these areas were joined together in a paradigm that involves a coincident-timing task in which a moving target is intercepted by a level controlled by a flexion-extension movement at the elbow joint. With analyses that allow the description of programmed units of behavior, we show that practice with KR resulted in a large and systematic reorganization in movement control. In early practice, subjects produced a single, preprogrammed bi-directional action. However, in later practice, subjects segmented this action into two independently controlled parts. This reorganization was characterized by a pause in movement after the backswing (flexion) a variable period in which subjects presumably processed visual feedback from the display and then a second programmed forward swing (extension) movement to strike the target. These segmented patterns acquired via practice and KR suggested changes in motor control with practice that were counter to predictions from several current viewpoints about skill acquisition.
