Figure 1.

Experimental tasks (top panels) with corresponding exemplar control data (bottom panels). (A) Visually guided reaching: Motor control was measured by quantifying reaching behavior in a standard center-out reaching task. An exemplar control (bottom panel) depicts intact reaching behavior with straight, accurate reaches to each of the four targets along with consistent hand speed performance taken from a single target. (B) Position matching: The robot moved the subjects' arm (top panel, right arm in example) to one of nine locations in the workspace. Subjects then mirror-matched the location of the robot movement (top panel, left arm) to where they had sensed their arm had been moved. The exemplar control (bottom panel), demonstrates that the subject (open symbols) could accurately match the locations of the robot movement (black closed symbols). The dotted gray line shows the outline of the subject's data from the outer 8 points mirrored directly onto the robot workspace for visualization purposes. (C) Kinaesthetic matching: The robot moved the subjects' arm (top panel, right arm in example) to one of three locations in the workspace. As soon as the subject felt the robot move their arm, they were to mirror-match the speed, direction and length of the robot-generated movement (top panel). The exemplar control (bottom panel), demonstrates that for a single direction of the task, the subject (open symbols, gray lines) was able to consistently and accurately match the direction and length of the robot-generated movement (closed symbols, black line). The dotted gray line shows subject performance mirrored directly onto the robot movement for visualization purposes.