Effects of finger markers on the kinematics of reaching movements in young children and adults.

Kinematic studies to date have not considered in what ways surface markers may affect the performance of the analyzed motion. This neglect is particularly apparent in studies of prehensile movements involving surface markers attached to the fingers. In order to specify any such effects, a range of kinematic parameters derived from simple reach-to-grasp movements, both with and without finger markers, by 3-year old children and adults were analyzed. Finger markers affected both the spatial and temporal nature of the children's reaching performance as revealed by a more temporally segmented reaching path, an age-atypically straighter reaching path, and an increased time to establish a pincer grip. The reaching movements made by the adults were unaffected in terms of the kinematic parameters employed.