Tactile-kinaesthetic perception of straightness in blind and sighted humans

A comparison is made between the tactile-kinaesthetic perception of straightness in twenty blind and twenty sighted subjects. Both types of subject are found to perceive a “plus curved” edge as straight, but this curve is significantly less for the blind than for the sighted, i.e. the blind subjects' judgments correspond more closely to the objective straight. Furthermore, the blind, both as individuals and as a group, are significantly finer in their judgments and more consistent. These results are thought to be explained in terms of the more highly developed organisation of the blind's tactile-kinaesthetic perception.