An active kinesthetic-to-visual matching task was performed by 15 children
aged 5-10 years and five young adults. The task required the participants to locate the target visually while performing center-out drawing movements to the located
visual targets in the absence of
visual feedback of
hand/pen motion. Movement time (MT), terminal end-point position error (EPE), and initial directional error (IDE) were measured. The general finding is that the end-point error variability, representing the
joint localization
probability distributions for
proprioceptive localization of the
hand and
visual localization of the target, was largest for the youngest children, but did not differ from one another for the older age groups. The localization distributions, as characterized by
principal component analysis, showed that both errors in extent and direction were significantly larger in the youngest children. These
error distributions could not be accounted for by initial localization errors
prior to movement onset in the children. It is likely that at least some portion of the increased movement variability seen during sensorimotor development in young children can be attributed not only to immature control mechanisms per se, but also to partial, not yet stable, forward representations for
hand localization which are used for
movement perception,
planning, and control.
