Figure 3.

The presence of a perceptual shift depends on motor learning. In a control experiment, subjects experience the same trajectories as individuals that display motor learning. Subjects make active movements in the null and aftereffect phases of the study. In the force-field training phase, they are moved passively by the robot to replicate the average movement path experienced by subjects in the leftward condition that show motor learning. The top shows mean movement curvature (±SE) over trials for subjects in the original active learning condition (red) and the passive control condition (yellow). The bottom (magenta) gives the difference between active and passive movements. Movement aftereffects are not observed in the passive condition (yellow), indicating there is no motor learning.