U.S. Supreme Court justices and other federal judges are, effectively, appointed for life, with no built-in check on their cognitive functioning as they approach old age. There is about a century of research on aging and intelligence that shows the vulnerability of processing speed, fluid reasoning, visual-spatial processing, and working memory to…

The two featured articles and eight commentaries on the WISC-IV (Wechsler, 2003) and WAIS-IV (Wechsler, 2008) in this special issue of "Journal of Psychoeducational Assessment" are of exceptional quality. As a collective, this special issue greatly advances the field of cognitive assessment by intelligently synthesizing the best of…

Six abilities derived from the fluid and crystallized intelligence theory of J. L. Horn were studied with 1,193 individuals in age groups between 15 and 94 years. Results supported Horn's classification of crystallized and quantitative as maintained abilities and of fluid and broad visualization as vulnerable abilities. (SLD)

Examined age changes in intellectual ability in the range from 16 to 89 years through 2 studies that involved IQs on the Wechsler Adult Intelligence Scale III (WAIS-III). Results are interpreted in the context of the fluid-crystallized intelligence theory of J. Horn. Studies used WAIS-III standardization data for 2,450 adults and longitudinal data…

Results from 1,297 adolescents and adults show that, consistent with hypothesized relationships, people classified as Intuitive by the MBTI earned higher KAIT Composite IQs than those classified as Sensing. However, most other hypotheses were not supported, as the Fluid-Crystallized discrepancy was not meaningfully related to any MBTI dimension.…

Data from 255 normal individuals were factor analyzed. Variables included subtests from the Wechsler Adult Intelligence Scale-Revised (WAIS-R), the Kaufman Adolescent and Adult Intelligence Test (KAIT), and two new brief measures. Results are interpreted in the context of previous Horn analyses of the KAIT and WAIS-R. (SLD)

Age differences in intellect as reflected in performance on the revised Wechsler Adult Intelligence Scale (WAIS-R) from age 20 to 74 years were evaluated for 1,480 adults from the WAIS-R standardization sample, while educational levels were held constant. Implications of the results for intelligence testing are discussed. (SLD)

Factor-analyzed data are reported from the Kaufman Adolescent and Adult Intelligence Test for 1,535 whites, 226 African Americans, and 140 Hispanics. Factor structures yielded Fluid and Crystallized dimensions that were congruent across race and ethnic groups and provided construct validity for each subsample. (SLD)