As a first step, the investigators will determine movement times, accuracy, smoothness, segment and joint rotations and the main components of multi-joint coordination. Cartesian coordinates (x,y,z) for each segment will be obtained from the segmental marker sets. Raw data from at least three markers per segment will be used after interpolation of missing markers (5th-order polynomial). For each trial, movement times and peak velocities will be determined from endpoint tangential velocity traces. Movement time is the time between the point at which the tangential velocity exceeds and remains above 5% of its maximum and then returns to and remains below this level. Movement accuracy in terms of constant extent errors will be computed as the mean distance (d) between the final endpoint position (x, y, z) and the position of the target (x0, y0, z0). Constant and variable (SD) directional errors will also be defined. Movement smoothness will be computed from the tangential velocity trace using the index of curvature (ratio of endpoint path length to length of a straight line joining the initial and final positions) and the number of peaks in the trajectory path. For segment and joint rotations, vectors will be calculated within reference coordinate systems for the upper and forearm segments.