Tactile perception in blind Braille readers: A psychophysical study of acuity and hyperacuity using gratings and dot patterns

It is not clear whether the blind are generally superior to the sighted on measures of tactile sensitivity or whether they excel only on certain tests owing to the specifics of their tactile experience. We compared the discri mination performance of blind Braille readers and age-matched sighted subje cts on three tactile tasks using precisely specified stimuli. Initially, th e blind significantly outperformed the sighted at a hyperacuity task using Braille-like dot patterns, although, with practice, both groups performed e qually well. On two other tasks, hyperacute discrimination of gratings that differed in ridge width and spatial-acuity-dependent discrimination of gra ting orientation, the performance of the blind did not differ significantly from that of sighted subjects. These results probably reflect the specific ity of perceptual learning due to Braille-reading experience.