Early stages of tactual matching.

Naive sighted subjects tested under blind conditions were able to match raised dot (Braille letters) patterns relatively accurately by touch, but showed no advantage in judging identical pairs over different pairs of patterns. This was the case also for letters subjects had been taught to name. Instructions to match on name or feel had significant effects, but these did not relate differentially to "same"/"different" judgments. Under visual conditions subjects matched "same" letters faster than "different" letters. Errors in drawing the letters after tactual exposure and naming training showed that subjects had no accurate idea of the spatial relations or configuration of the dot patterns. The findings suggested that early stages of tactual matching involve exhaustive comparisons and rechecking of features, and that correct notions of tactual dot configurations may be built up rather slowly, and depend on identifying features along orthogonal axes.