Previous research has supported the theory that acquisition of expertise in any domain is possible for healthy individuals with sufficient deliberate practice, but such an extreme environmental position brings the existence of innate talent into question. The present study investigates the effects of both environmental factors and talent on expert…

SES has long interested researchers investigating school achievement. Its effects are often addressed by studying predictors of achievement in economically disadvantaged samples living primarily in biological families, confounding genetic and environmental influences. Little is known about SES's purely environmental effects. We measured them in…

Hierarchical factor analyses involving Schmid-Leiman transformations were conducted on specific cognitive abilities data collected from 148 identical and 135 fraternal twin pairs from the Western Reserve Twin Project. Model fitting results reflect genetic influences on specific abilities and suggest that environmental influences are less…

Data from a previous adoption study using the Wechsler Intelligence Scale for Children-Revised show that the genetic effect is reflected by psychometric "g" (general intelligence) to a greater degree than is the environmental effect. This finding is consistent with the hypothesis that "g" largely reflects the genetic component…

Taylor (1980) claims to show that the similarity in IQ between monozygotic twins reared apart found in prior studies is due to similarity in their environments. A reanalysis using Taylor's classification of environments but an alternative IQ measure shows that his findings do not constructively replicate. (Author/RD)

Data from 236 pairs of black twins and white twins aged 13-17 years were used to examine genetic and environmental factors influencing cranial size, an indirect estimate of brain volume. Genetic factors are required to account for the phenotypic variance in cranial capacity. (SLD)

Discusses work by Arthur Jensen in addition to his well-known work on the genetics of intelligence. Includes studies of learning, memory, the cumulative-deficit hypothesis, Spearman's hypothesis, and the speed of information processing. (SLD)

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…

Whether genetic and environmental effects on academic achievement changed as a function of the quality of children's environment was studied with 1664 pairs of full siblings, 366 pairs of half siblings, and 752 pairs of cousins. Little evidence was found of genotype-environment interactions. (SLD)

Comments on the work of Arthur Jensen, specifically "The g Factor" (1998), which consolidates the psychometric, neurophysiological, behavior genetic, and comparative evidence for the existence and importance of a factor of general intelligence ("g"). Discusses Jensen's work on black/white differences in intelligence. (SLD)

Discusses the contributions of Arthur Jensen to the study of intelligence and considers his writings on the topic of racial differences in scores on tests of intelligence. Concludes with a discussion of his work on the correlates of the "g" vector (general intelligence factor). (Author/SLD)

The genetic relationship between intelligence and components of cognition remains controversial. Conflicting results may be a function of the limited number of methods used in experimental evaluation. The current study is the first to use CANTAB (The Cambridge Neuropsychological Test Automated Battery). This is a battery of validated computerised…

Genetic research on intelligence has moved beyond the nature-nurture controversy to investigate developmental change and continuity, associations among cognitive abilities, and the developmental interface between nature and nurture. Advances in molecular genetics are leading to a new era of research. (Author/SLD)

Studied continuity and change in general cognitive ability from infancy to adolescence in adoptees (107 children), biological siblings (87 pairs), and twins (224 monozygotic and 189 dyzygotic pairs). Findings generally support previous findings about genetic and environmental factors, with the exception that in the transition to adolescence,…

This book, a critique of "The Bell Curve" by R. Herrnstein and C. Murray, explores what "inequality" in society means, how it arises, and how it can be measured or dealt with quantitatively. It also considers how societal and other variables work to increase or decrease inequality. The book argues that "The Bell…