Abstract

The present study attempted to investigate age associated change in IQ in adulthood by analysing K-WAIS standardization data. The results indicated that scaled scores of verbal and performance subtests declined steadily with age. When education level was controlled, the rate of decline in scaled scores was considerably reduced, but the basic pattern of decline with age remained unchanged. Multiple regression analysis with the educational attainment and age as predictors of scaled scores revealed that education accounted for 54.4%, 49.9%, and 56.5% of variance in the sum of scaled scores of the verbal subtests, performance subtests, and all subtests, respectively. Adding age as another predictor led to an increment of 13.1% of variance accounted for in the sum of performance subtest scaled scores, and 4.1% in the sum of verbal subtest scaled scores. Age increased prediction of the total sum of scaled scores was 8.1%. The results were interpreted to mean that age associated changes in K-WAIS performance could not be accounted for by educational attainment alone.