Chapter 2 Intermittent Versus Continuous Control of Manual Aiming Movements

Publisher Vision is important for limb control, but continuous visual monitoring of the limb and movement environment is not always necessary. This chapter focuses on the issue of visual intermittency and the control of arm and hand movements and reviews the experiments that suggest that a brief visual representation of the movement environment may, at times, provide an adequate replacement for more direct visual information. This representation allows several situations to move accurately to targets in space even when vision is occluded for a short period of time. The chapter examines the role of vision in the control of limb movements by manipulating its presence/absence during the movement. In many studies, the major goal is to determine the time an individual takes to use visual feedback about the position of the limb in space for improving the accuracy of the movement. When one considers typical closed-loop explanations of limb control, the degree of precision that can be achieved without vision is all the more surprising. Specifically, most closed-loop models of limb control posit that visual, kinesthetic, and feedforward information about limb position must be compared to visual information about target position to detect and correct error inherent in the initial movement impulse.