Fig. 6.

Size and direction of after-effects as subjects learn field B₂ at different time intervals after practicing in B₁. Size is determined as the distance from a straight line (from the previous to the next target) at 300 msec into the movement. Direction is positive for an after-effect appropriate for field B₁ (i.e., counter-clockwise, as in Fig. 2) and negative for an after-effect appropriate for field B₂. Plotted are the means and 95% confidence intervals. Each point represents the average after-effect for a group of subjects at a given movement number (bin size is 4). Because the size of after-effects depends on direction of target (e.g., Fig. 2F), the change for a given curve is not expected to be monotonic. However, the sequence of targets for all subjects is the same. Therefore, after-effects at a movement number may be directly compared among the different groups. The figure shows that at 5 min after learningB₁, subjects begin learningB₂ with after-effects that are in the direction of B₁. Control subjects who never learned B₁ begin learningB₂ with no after-effects, i.e., unbiased. With temporal distance between training sessions, initial after-effects begin to resemble those of the control group.