Smyth Mary M, Katamba Janet, Peacock Kirsty A
Department of Psychology, Lancaster University, England.
J Mot Behav. 2004 Mar;36(1):91-103. doi: 10.3200/JMBR.36.1.91-103.
The authors investigated whether 5- to 10-year-old children (N = 75) differ from adults (N = 12) in the developmental course of distance scaling and the adaptations to the inability to see the hand during prehension movements. The children reached under a surface and grasped and lifted an object suspended through it. All children scaled velocity appropriately for movement distance, both with and without sight of the hand. However, 5- to 6-year-old children did not increase grip aperture with increased distance, whereas older children and adults did. The older children and adults spent longer after peak deceleration when they could not see the hand, and maximum grip aperture (MGA) was larger, providing an increased safety margin. Children aged 5 to 6 spent the same amount of time between peak deceleration and grasp, whether or not they could see the hand, and they failed to increase MGA when they could not see the hand. Prehension in the younger children differed from that of older children in two ways: The younger children did not integrate reach and grasp over different distances and did not use visual information about hand position to optimize accuracy.
作者研究了5至10岁儿童（N = 75）与成年人（N = 12）在距离缩放发展过程以及抓握动作中看不到手时的适应情况是否存在差异。儿童在一个平面下伸手，抓住并提起通过该平面悬挂的物体。所有儿童无论是否能看到手，都能根据移动距离适当地调整速度。然而，5至6岁的儿童不会随着距离增加而增大抓握孔径，而年龄较大的儿童和成年人会。年龄较大的儿童和成年人在看不到手时，在峰值减速后花费的时间更长，且最大抓握孔径（MGA）更大，从而提供了更大的安全边际。5至6岁的儿童在峰值减速和抓握之间花费的时间相同，无论他们是否能看到手，并且当他们看不到手时，他们不会增大MGA。年幼儿童的抓握与年龄较大儿童的抓握在两个方面存在差异：年幼儿童不会在不同距离上整合伸手和抓握动作，也不会利用关于手位置的视觉信息来优化准确性。
