Aspects of size, shape and texture in touch: redundancy and interference in children's discrimination of raised dot patterns.

Children discriminated tactual dot patterns by size or form and by texture. Adding irrelevant, easy, correlated texture cues improved size and form discrimination while orthogonal irrelevant texture cues interfered. Facilitation and interference could be reversed by reversing dimensional difficulty, but were found also when the two dimensions were equally accurate, for both blindfolded sighted and for blind children. The theoretical implication with regard to age effects, and practical implications for using dot numerosity and dot density differences for Braille learning were discussed.