Figure 2.

Prism adaptation and aftereffect in groups 1, 4, and 5. Plots of trial number vs. horizontal displacement from the target for throws made before, while, and after the subjects donned 30-diopter prism lenses. The addition of weight to the throwing arm (groups 4 and 5) during the PRE and PRI trials had no effect on the performance of the task or on the onset of the adaptation. However, the weight–no weight transition between PRI and POS was associated with a smaller aftereffect. Furthermore, the reinstatement of the load halfway through the POS trials led to the appearance of a second, late aftereffect in both experimental groups. Data represent means ±s.e.m.