Figure 2.

Adaptation and generalization in the biomechanics. Panel (a) presents the average trajectories observed at Baseline (red), Ad1/Ad3 (blue), Ad4/Ad6 (green), Wo1/Wo2 (blue) and Wo3/Wo4 (green). For each plot the lighter color presents the average of the first 2 movements in the first block listed on top (e.g. Ad1) and the darker color presents the average of the last 2 movement in the second block listed on top (e.g. Ad3). For baseline, the average of the last 5 movements of B3 is presented. For each target we observed an increase in movement curvilinearity at the onset of the perturbation (b) followed by an adaptation and a second increase when the perturbation is removed. Similar behaviors were observed during adaptation (light blue) and generalization (light green) although generalization was characterized by smaller initial deviations at the onset and offset of the perturbation for all targets with the exclusion of target SW. The average normal curvilinearity was significantly higher at the beginning of adaptation with respect of generalization across all targets (c). **denotes p < 0.01, using Mann-Whitney U test. Panel (d) shows the average values of generalization (calculated as the average difference in NC between Ad1 and Ad4 across the subjects) for the targets as a function of the number of pre-adapted adjacent targets.