Older and younger adults' strategies in sensorimotor tasks: insights from Fitts' pointing task.

We investigated how young and older adults differ in sensorimotor tasks. Two groups of participants (young and older adults) performed discrete Fitts' tasks in which 4 levels of difficulty (ID) were used, resulting from either the manipulation of the size of the target (ID(W)) or of the distance between home and target positions (ID(D)). Kinematic analysis allowed distinguishing 4 different types of strategies used to reach the target, on the basis of the existence and the nature of submovements. Results showed that the repertoire of strategies was significantly smaller in older than in young participants. In addition, the frequency of use of the different strategies varied with participants' age. Specifically, the most frequent strategies used by older participants included submovements, while those used by young participants did not include submovements. The differences observed between young and older adults were independent of whether ID was manipulated via target size or movement distance. Finally, age-related differences in strategy performance were found. These results have important implications for furthering our understanding of aging effects in sensorimotor tasks. They also illustrate the usefulness of a strategy approach in a domain where it had never been formally used before.