Over life-span tactile perception undergoes many changes either caused by altered use or by age. We here address the question how enhanced hand use in blind subjects affects tactile acuity and tactile learning abilities.
We tested 4 groups of young and old early and late-blind subjects and compared them to age-matched control groups of sighted people. A static two-point discrimination task was used to measure tactile acuity on the index fingers of both hands. To induce learning processes we applied a tactile stimulation protocol to the tip of the Braille-reading finger. This so-called coactivation protocol is based on Hebbian Learning and has been shown to drive substantial improvement of tactile acuity in young and elderly subjects.
Young blind and sighted subjects showed only little differences in their discrimination thresholds, whereas tactile acuity thresholds in elderly were much higher in sighted than in blind people. The improvement in tactile acuity induced by coactivation was largely confined to elderly late-blinds. The results are discussed in relation to preservation of high levels of tactile acuity at high age, and in respect to consequences of learning-induced improvement of tactile acuity in blind subjects.