Age Reduces Motor Asymmetry in a Graphic Task.

The purpose of the present study was to compare motor asymmetry between older and younger adults performing a graphic task. Thirty-four right-handed older and 38 younger adults drewcontinuous cursive "l" loops on a digitizer tablet using their right and left hand, respectively, aimed to assess age-related hand asymmetry differences in the performance of movements. Primary dependent variables were mean velocity, peak velocity, stroke size, and the ratio of the duration to decelerate to the duration of the overall movement time (RDP). A 2-way mixed-design ANOVA with age-group as the between factor (young and old) and hand (left and right) as the within factor was conducted. The results showed a significant age-by-hand interaction for mean velocity (p = .012) and peak velocity (p < .001), supporting decreased asymmetry when aging after young adulthood. Further analysis revealed a greater decline in the dominant (right) hand compared to the non-dominant (left) hand which seems to be the origin of observed reductions in motor asymmetry across the lifespan.