Cognitive functioning of deaf young adults as determined by Wechsler Performance Scales

Abstract

This study examined the behavior of deaf young adults on the Wechsler Performance Scales relative to variables of deafness, type of schooling and degree of loss. It also compared performance results of the deaf young adults with performance of adults in general as reflected by Wechsler Adult Intelligence Scale-Revised (WAIS-R) standardization norms. Subjects for the study were from Dallas and Houston Regional Day School Programs for the Deaf and from Texas School for the Deaf, located in Austin. One hundred eighty protocols revealed Performance IQ and five subtest scaled scores for each subject; these constituted the six dependent variables. Analysis of Variance was used to investigate main effects for type of schooling and degree of loss on the dependent variables and possible interaction effects between the two factors (schooling and hearing loss). A one-sample t-test compared the Performance IQ (PIQ) mean and the subtest scaled score means of the study's sample to the WAIS-R PIQ mean of 100 and the subtest scaled score mean of 10 at the.05 and.01 levels of significance. Measures of central tendency and variability were used to examine patterns of performance. Results revealed no significant differences between test means on performance of deaf young adults for degree of hearing loss. Type of schooling yielded significant differences on the PA and BD subtests; however, less confidence can be placed on the PA subtest because of unequal variances. The study's sample scored statistically different from the means of the national normed group. There is a distinct pattern of performance as found in samples of deaf children. The group did not produce scores which "fall toward the mean" as suggested by the developmental theory that scores improve with age for deaf individuals. The unexpected finding that this sample of deaf young adults in Texas scored about one standard deviation below the norm negates the claim of Vernon and others that deaf individuals score within the normal range when non-verbal measures are used. Possible explanations for the discrepancy are presented as relating to such factors as the selection of tests, the individuals' approach to test-taking, skill of examiners, use of interpreters. Recommendations for further study with more controlled conditions are outlined.