abstract
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In recent years, many studies have reported that the tactile spatial acuity of blind participants is enhanced relative to that of sighted participants, but it is unclear what factors drive this enhancement. In the series of three psychophysics studies (of tactile spatial acuity) presented in this thesis, we attempted to tease apart two hypotheses explaining tactile spatial acuity enhancement in the blind: visual deprivation and tactile experience. To measure tactile spatial acuity in these studies, we used a grating orientation task. In the first study (Chapter 2), we found that blind participants outperformed sighted participants, but only on body parts where tactile experience is presumably greater in blind than in sighted participants (i.e., fingertips, not lips); we found additionally that blind participants’ tactile acuity correlated with their Braille reading behaviour (e.g., style, frequency of reading). In the second study (Chapter 3), we found that visual deprivation of sighted participants for periods up to 110 minutes did not enhance their sense of touch. In the third study (Chapter 4), we found that extensive training on a tactile task can substantially improve sighted participants’ sense of touch. The findings from our three studies thus provide consistent support for the hypothesis that tactile experience, but not visual deprivation, drives tactile spatial acuity enhancement in the blind.