Reanalysis and Critique of “Sensory Discrimination” as an Ability Component of the Blind

Abstract

Juurmaa (1967) carried out the first comprehensive study to assess the ability domain of totally blind males. Using Thurstone's centroid method and graphic orthogonal rotation, 9 factors were extracted from a 23 × 23 intercorrelation matrix. Abilities measured included verbal comprehension, arithmetic reasoning, spatial ability, memory, dexterity, kinesthetic memory, tactual discrimination, and auditory sensitivity. One factor, “sensory discrimination,” was obtained from the blind group which had no corresponding factor in a sighted male comparison group. The purpose of the present study was to explore further the interpretation of this unique factor and to raise major methodological issues about Juurmaa's analyses, namely, the make-up of the blind sample, the choice of factor analytic tools, and the arbitrariness of the decision concerning dimensionality. Consideration of these issues in conjunction with a reanalysis of Juurmaa's data, led the authors to conclude that the ability structure of the blind needs considerably more research before any conclusions can be drawn without extreme caution.