Visual cues and the handwriting of older adults: a kinematic analysis.

Kinematic techniques determined the nature of any age-related changes in the fluency of handwriting movements and also the extent to which any changes can be related to a differential utilization of visual feedback. To quantitatively document the kinematics of handwriting movements, 24 young and 24 older adults were compared by having them write simple cursive letter ls 4 times on a graphics tablet, under 4 different visual conditions (no vision, non inking pen, inking pen, and lined paper). Pen tip position was sampled at 200 Hz, from which kinematic indexes of movement efficiency and consistency were derived. Quantitative differences in movement trajectories were found in the older adults, who produced less efficient movements with a concomitant increased utilization of external visual cues. Older adults made a differential use of visual feedback to modify movement trajectories, rather than to control the effects of neural noise. Handwriting movements of older adults resembled only to a limited extent those of patients with Parkinson's disease.