ROLES OF VISUAL INFORMATION FOR CONTROL OF REACHING MOVEMENTS IN CHILDREN

What visual information do children normally require for the control o f reaching movements? How is performance affected when children do not have access to the preferred mode of perceptual information? These qu estions were studied in 28 children who were tested on 3 occasions: at 6, 7, and 8 years of age. The task was to pick beads, 1 at a time, fr om 1 cup and carry them to another cup. With the aid of a mirror arran gement and a curtain, the amount of visual information was manipulated with regard to both the target and the performing hand. The movements were monitored with an optoelectronic device (SELSPOT II) and analyze d in terms of transport and object-handling phases. Results showed tha t object handling required visual information on both hand and target. For the transport phase of the movement, visual information on the sp atial location of the target was sufficient, and sight of the hand did not improve performance. In contrast to adult subjects, when children did not have access to the required visual information, their perform ances deteriorated markedly. These results indicate that from the age of 6, children use visual information for control of arm movements in a manner like that of adults, although with less accuracy and speed. H owever, even 8-year-old children are limited in their ability to use a lternative perceptual strategies for movement control, and they theref ore become less flexible and more dependent on visual information.