Tactual Maps: Discriminability of Textures and Shapes
Robert B. Horsfall, Deborah C. Vanston · Journal of Visual Impairment & Blindness · 1981
Report of a study of the discriminability of point symbols in tactual maps which showed that the three shapes and four textures tested are distinguishable in sizes 7.9 mm (.3 in.) and larger. Suggestions for the use of textures in tactual maps are offered.