Two modes of error processing in reaching.

Several processes are devoted to error reduction for the production of purposeful actions. When motor responses deviate from their goal, online corrections can be performed either under voluntary control with additional sub-movements or under fast automatic control with smooth velocity profiles. When errors cannot be corrected online and are repeated over trials, subsequent responses can be improved iteratively through adaptation, a progressive adjustment of motor commands that acts to reduce the magnitude of error.

A joint-centred model accounts for movement curvature and spatial variability.

Hand reaching toward a visual target needs the central nervous system (CNS) to encode target location and initial limb posture. Once these sensory inputs are encoded within a common frame of reference, the motor system builds a motor command to drive the limb towards the target. In order to face the controversy concerning the variables (in task-space versus joint-space) the motor system may manipulate to build a motor command, we propose to compare recorded hand pointing movements to a task-space vector model and to a simplified joint-centred model.