The role of sight of the hand in the development of prehension in childhood.

In two studies, children between 5 and 10 years of age were asked to reach to grasp an object without sight of the hand during the movement. The oldest children and adults were faster when they could see the hand and increased maximum grip aperture when they could not see the hand. The 10-year-olds were less able to integrate grasp and lift than adults when they could see their hands. Children aged 5 and 6 showed no increase in movement time when they could not see the hand and did not adapt maximum grip aperture to lack of sight. These effects remained when children were encouraged to reach for and lift the target as quickly as possible. The results indicate that younger children did not give preference to vision in the control of prehension, while older children used visual feedback to improve efficiency. Dependence on sight of the hand for the control of prehension does not simply decrease with age, but it may be integrated into an anticipatory control strategy where it contributes to the efficiency of control.