Visual-Motor Integration of Unexpected Sensory Events in Young and Older Participants: A Kinematic Analysis

We report a single experiment that examined the ability of young and older participants to modify their movement plan on-line during movement execution. Participants performed a single phase aiming task under 2 different conditions. In the experimental condition, during 76% of the trials, the index of difficulty of the task remained constant at 4.8 bits (medium target). During 24% of the trials, target width changed unexpectedly at movement initiation to either a smaller (6.1 bits) or larger (3.5 bits) target. In the control setting, participants completed trials to each target (3.5, 4.8, or 6.1 bits); target width remained constant throughout movement in this condition. For both age groups, participants responded in the anticipated fashion during control trials; movement time increased as a function of target size, with older participants generally performing more slowly. In the experimental condition, the young participants adapted their performance to the new target characteristics. In contrast, older ...