Evaluating the Intellect of Blind Children

Abstract

The purpose of this study was to evaluate the adequacy of the WISC and the Hayes-Binet as measures of the intelligence of blind children. Thirty subjects, most of whom were in a residential school for the blind, were given both of these tests and the results compared. The mean scores on the two tests were at the borderline level, but there was considerable variation. The correlation between the two tests was 90, and the difference found in the means was not reliable. The test-retest correlation of twenty WISC cases was .91, and again, the difference between the two means was not reliable. Analysis of the sub-test scores of the WISC shows the Digit Span score to be reliably superior to all other scores on the WISC. It is thought that this elevation of the Digit Span score sometimes might so raise the IQ as to give an inaccurate picture of the actual mental ability of the blind child. It would appear that because of the similar results yielded by these two tests, the fact that the WISC is shorter, easier to give, and less tiring to the blind child, makes it desirable to use in place of the Hayes-Binet in many instances. However, if the WISC is used it would be well to supplement it with a test of meaningful verbal memory so that some appraisal can be made of the child's learning ability. A new test of general intelligence standardized on blind children is greatly needed. It would be advisable to pattern this after the WISC, but to modify the Comprehension and Similarities tests along lines more suitable for blind children and to include a test of verbal reasoning and one of meaningful verbal memory.