The development of the adult-like strategy for reaching movements in childhood.

This study was undertaken to follow the development of the capability to produce fast and precise movements reaching to visual targets, during childhood. One child (male) was tested repeatedly since age 6, until age 9. Accuracy increased progressively, while reaction and movemet times decreased, eventually approaching those typical of the adult. The most prominent finding is that our subject changed the strategy adopted for reaching to targets at different distances, from “width control” to “height control”: when youngest, he scaled movement times of trajectories mainly (width control); when older, he scaled peak velocity of a stereotyped bell-shaped trajectory (height control), thus adopting a fully adult-like strategy. The results were confirmed in two groups of 5 children each, aged 6 and 9 respectively. It is concluded that, between age 6 and 9, children become capable of producing both quick and accurate trajectories to target, by implementing the optimized "height control" strategy typical of adult