A confusion matrix of the whole block capital letters of the alphabet was obtained to examine the nature of tactile letter recognition. A 17 x 17 matrix of tactile stimulators was placed against the backs of 4 blind Ss. A hierarchical cluster analysis {\&} a nonmetric multidimensional scaling technique were applied to the matrix. Results of the two analyses were consistent with each other, {\&} indicated that at least three independent basic letter features - enclosing shapes, vertical parallel lines, {\&} angle of lines - play important parts in tactile letter recognition. Most confusion may be attributable to displacement of the apparent loci, omission or fusion of loci of stimulation, {\&} failure to detect gaps in the tactile letters. 1 Table, 6 Figures. HA
The subjects were asked to confirm the shapes of the alphabet further by touch. Then they had practice in order to familiarize themselves with this equipment.