Prism adaptation in normal aging: slower adaptation rate and larger aftereffect.

The effect of aging on prism adaptation, a motor learning paradigm, was evaluated. Different measures were obtained from a task consisting of throwing clay balls to a target in front of the subjects before, during, and after wearing prisms that deviate the visual field by several degrees. When performing the task without wearing the prisms, the aged subjects showed a larger hit variance, whereas the young subjects hit closer to the target. When donning the prisms, the aged group adapted more slowly than the controls, although after throwing all the balls both groups showed the same adaptation levels. After removing the prisms, the aged group showed a larger aftereffect. These findings suggest that the aftereffect requires the involvement of non-cognitive and cognitive processes and indicate that both adaptation and aftereffect are influenced by aging.