Are corrections in accurate arm movements corrective?

Publisher Summary At any rate, the difference between movements with and without a precise goal is interesting because it demonstrates that the longer deceleration observed when a high accuracy is required must be due to an active process for bringing the movement at the target, rather than to passive counteracting forces. A longer deceleration implies that a certain level of velocity is maintained in the later part of the trajectory in order to cover residual distance before the stop. In fact, significance of asymmetry of the velocity curve is difficult to interpret, particularly, in the case of the moving segments with a high load, such as the arm. In that case, the apparent smoothness of the deceleration curve could be an effect of filtering out smaller re-accelerations during the deceleration phase. The time for visual feedback to be effective can be much shorter than 200 mseconds, and therefore, visual feedback could improve final accuracy by acting during the movement generated by the initial impulse, and not only after completion of that movement. Second, as is shown in the chapter, secondary movements may be present in situations where no visual feedback from the moving limb is available, which excludes visual corrective mechanisms.