The ranking of Wechsler subtests in terms of their "g" loadings is equivalent to ranking them in terms of the cognitive complexity of the tasks measured. Lower performing groups do not always fall behind higher performing groups the more complex the task. But that is the general rule, no matter whether the cause of the lower performance…

On the basis of several reviews of the literature, Lynn [Lynn, R., (2006). Race differences in intelligence: An evolutionary analysis. Augusta, GA: Washington Summit Publishers.] and Lynn and Vanhanen [Lynn, R., & Vanhanen, T., (2006). IQ and global inequality. Augusta, GA: Washington Summit Publishers.] concluded that the average IQ of the…

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)

Recent work with the 42 mental ability tests administered to participants of the Minnesota Study of Twins Reared Apart (MISTRA) has suggested that there are important dimensions of mental ability that function independently of "g". Two of these dimensions, rotation-verbal and focus-diffusion, appear to involve trade-offs: greater…

Used the Spanish standardization of the Wechsler Adult Intelligence Scale III (WAIS III) (n=1,369) to test the age dedifferentiation hypothesis. Results show no changes in the percentage of variance accounted for by "g" and four group factors when restriction of range is controlled. Discusses an age indifferentation hypothesis. (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…

We investigated sex effects and the effects of educational attainment (EA) on the covariance structure of the WAIS-III in a subsample of the Spanish standardization data. We fitted both first order common factor models and second order common factor models. The latter include general intelligence ("g") as a second order common factor.…

Whether cross-sectional rates of decline for brain volume and the Performance Intellectual Quotient of the Wechsler Adult Intelligence Scale-Revised were equivalent over the years 16 to 65 was studied with 196 volunteers. Results indicate remarkably similar rates of decline in perceptual-motor functions and aging brain volume loss. (SLD)

Three experiments investigated the possibility that adult age differences on block design tasks originate because of reduced efficiency with increased age in the cognitive processes associated with block manipulation. Older adults were substantially slower and less efficient than younger adults in performing tasks with minimized design…

Correlations on subscales of Wechsler intelligence quotient tests and the Revised Beta Examination were obtained for biologically related and unrelated individuals in 181 adoptive families in the Texas Adoption Project. Generally higher correlations for biologically related individuals support the importance of genetic influence in intellectual…

First, third, fifth and eleventh graders were videotaped as they completed the Block Design Subtest of the WISC-R. Neither the order of placement of blocks within each design nor the degree to which children persisted in placing a given block correctly before moving to the next one evidenced developmental differences. (Author/RD)

Items showing sex differences on the revised Wechsler Adult Intelligence Scale (WAIS-R) were studied. In a sample of 206 young adults (110 males and 96 females), 15 items demonstrated significant sex differences, but there was no relationship of item-specific gender content to sex differences in item performance. (SLD)

Three forms of a symbol-digit substitution task were administered to 62 female and 96 male college students. Results support the theory that the superior performance of women over men on the Digit-Symbol Substituion subtest of the Wechsler scales is due to their greater ability to encode symbols verbally. (Author/JAC)

Change in cognitive functioning is an important aspect of human aging and a key outcome in many medical conditions. However, cognitive change can rarely be measured directly, since prior cognitive data do not exist for most people. We examined the criterion validity and one-year stability of the difference between National Adult Reading Test…

Infants judged to be at risk for subnormal intellectual growth were randomly assigned to experimental and control groups which varied as to educational curriculum activities. Two types of evidence, group differences and parent-child IQ correlations, demonstrate the importance of early environments in intellectual development. (Author/RD)