Echo perception of shape and texture by sighted subjects.

Experienced blind subjects have previously demonstrated good echo perception of size and distance and some echo-discrimination of shapes and textures. In three experiments untrained sighted subjects also proved able to echo-detect and recognize three simple shapes and to recognize fabric and wooden but not carpet and Plexiglas discs at significantly above chance levels. Some improvement occurred over the first few trials but little thereafter, suggesting that this sort of echo perception requires very little training. A blind subject exhibited over-all accuracy comparable to those of sighted subjects. There were, however, interesting differences between the blind subject and the sighted subjects in echo perception of specific stimuli and in approach to the task.