AGING AND RAPID AIMING ARM MOVEMENT CONTROL

The authors explored the motor control of target-oriented arm movement s across 3 age groups: 20 20- to 30-year-olds, 2 groups (n = 38) of ol der adults (54 to 64, and 65 to 80). Each individual completed 2 arm m ovement tasks that had the same movement difficulty but different move ment directions. A mixed design was used to examine the differences am ong age groups and movement directions in reaction time (RT), variabil ity in RT, movement time (MT), timing variability and inter-segment-in terval (ISI). Comparing to the young participants, the senior adults i nitiated movement tasks slower (RT) and with more RT variability, and executed the arm movements slower and less consistently. The two older groups had greater timing variability in their movements, showed more delays (longer ISI) when reversing arm movement direction, and had lo wer correlations among segments of the movements than the younger grou p. The quality of the elderly's control of rapid aiming arm movements showed a regression, which suggests a lack of movement planning, resul ting in greater use of visual feedback during movement execution.