Ashmead D H, McCarty M E, Lucas L S, Belvedere M C
Bill Wilkerson Hearing and Speech Center, Vanderbilt University, Nashville, TN 37212.
Child Dev. 1993 Aug;64(4):1111-27.
This experiment evaluated the role of visual input about the location of a target object and the location of the hand in reaching by infants and adults. 5- and 9-month-old infants were presented with illuminated toys to reach for in a dark room. On no-switch trials, the toy remained illuminated throughout the infant's reach, whereas on switch trials the first-lit toy was replaced during the reach by a second-lit toy at a different position. On approximately half of the trials of each type a luminescent marker was attached to the reaching hand. Adult subjects (tested without the hand marker) fully compensated to the second-lit toy on switch trials, during a second reaching segment. On switch trials, 9-month-olds partially adjusted to the second-lit toy when wearing the hand marker and did not adjust without it. On no-switch trials, 9-month-olds reached just as accurately with or without the hand marker. 5-month-olds were generally inaccurate in their reaching and were unaffected by the presence or absence of the hand marker. The findings suggest that during the development of reaching there is an increase in visual guidance during the approach phase of reaches.
本实验评估了视觉输入在婴儿和成人伸手够物时对目标物体位置和手部位置的作用。在黑暗的房间里，向5个月和9个月大的婴儿展示发光玩具让他们去够。在无切换试验中，玩具在婴儿伸手的整个过程中一直发光，而在切换试验中，第一个发光的玩具在伸手过程中被不同位置的第二个发光玩具取代。在每种类型的大约一半试验中，一个发光标记附着在伸手的手上。成年受试者（在不使用手部标记的情况下进行测试）在切换试验的第二个伸手阶段，能完全向第二个发光玩具进行补偿。在切换试验中，9个月大的婴儿戴上手部标记时会部分调整去够第二个发光玩具，不戴时则不调整。在无切换试验中，9个月大的婴儿戴或不戴手部标记时伸手准确度一样。5个月大的婴儿伸手通常不准确，且不受手部标记存在与否的影响。研究结果表明，在伸手够物能力的发展过程中，伸手接近阶段的视觉引导有所增加。
