MENTAL ROTATION OF A TACTILE LAYOUT BY YOUNG VISUALLY-IMPAIRED CHILDREN

Mental rotation tasks have been used to probe the mental imagery both of sighted and of visually impaired people. People who have been blind since birth display a response pattern which is qualitatively similar to that of sighted people but tend to respond more slowly or with a h igher error rate. It has been suggested that visually impaired people code the stimulus and its (or their own) motion in a different way fro m sighted people-in particular, congenitally blind people may ignore t he external reference framework provided by the stimulus and surroundi ng objects, and instead use body-centred or movement-based coding syst ems. What has not been considered before is the relationship between d ifferent strategies for tactually exploring the stimulus and the respo nse pattern of congenitally blind participants. Congenitally blind and partially sighted children were tested for their ability to learn and recall a layout of tactile symbols. Children explored layouts of one, three, or five shapes which they then attempted to reproduce. On half the trials there was a short pause between exploring and reproducing the layouts. In an aligned condition children reproduced the array fro m the same position at which they had explored it; in a rotated condit ion children were asked to move 90 degrees round the table between exp loring and reproducing the layout. Both congenitally blind and partial ly sighted children were less accurate in the rotated condition than i n the aligned condition. Five distinct strategies used by the children in learning the layout were identified. These strategies interacted w ith both visual status and age. We suggest that the use of strategies, rather than visual status or chronological age, accounts for differen ces in performance between children.