Haptic equivalence matching of curvature by nonretarded and mentally retarded blind and sighted persons.

Retarded and nonretarded blind subjects were compared on haptic curvature matching tasks that varied in difficulty. All subjects' accuracy decreased with increasing task difficulty. Accuracy of nonretarded subjects did not differ as a function of visual status. Blind retarded subjects were more accurate than were sighted retarded subjects. The data were discussed in terms of haptic information-gathering experience.