Spearman's "law of diminishing returns" or SLODR refers to a decrease in "g" saturation as ability level increases. SLODR has been demonstrated in a number of intellectual batteries but several important aspects of the phenomenon are not yet well understood. We investigated the presence of SLODR in the Kaufman Assessment…

Previous studies based on population cohorts born at least 35 years ago, have reported appreciable childhood cognitive deficits for twins. We compared longitudinal IQ scores from approximately 188,000 singletons and some 6000 twins who went to primary school in the Netherlands from 1994 to 2003. In addition, we used a family-based design in which…

A historical increase in the number of factors purportedly measured by commercial tests of cognitive ability may result from four distinct pressures including: increasingly complex models of intelligence, test publishers' desires to provide clinically useful assessment instruments with greater interpretive value, test publishers' desires to…

This study explores whether or not intelligence tests' scores predict individual differences in scholastic achievement irrespective of SES factors such parents' income and education. The variables of interest are analyzed considering three independent samples of participants comprising a total of 641 children. The participants belonged to a…

To estimate Flynn effects (FEs) on forms of declarative memory (episodic, semantic) and visuospatial ability (Block Design) time-sequential analyses of data for Swedish adult samples (35-80 years) assessed on either of four occasions (1989, 1994, 1999, 2004; n = 2995) were conducted. The results demonstrated cognitive gains across occasions,…

Little is known about the association between measured intelligence and how people participate in democratic processes. In the 1970 British Cohort Study, we examined the association between childhood intelligence and, at age 34: whether and how people voted in the 2001 UK general election; how they intended to vote; and whether they had taken part…

Although it is widely acknowledged that chess is the best example of an intellectual activity among games, evidence showing the association between any kind of intellectual ability and chess skill has been remarkably sparse. One of the reasons is that most of the studies investigated only one factor (e.g., intelligence), neglecting other factors…

How important is intelligence to financial success? Using the NLSY79, which tracks a large group of young U.S. baby boomers, this research shows that each point increase in IQ test scores raises income by between $234 and $616 per year after holding a variety of factors constant. Regression results suggest no statistically distinguishable…

This research examined whether the SAT and ACT would predict college grade point average (GPA) after removing g from the tests. SAT and ACT scores and freshman GPAs were obtained from a university sample (N=161) and the 1997 National Longitudinal Study of Youth (N=8984). Structural equation modeling was used to examine relationships among g, GPA,…

Two pilot studies (n"1=155, n"2=451) are presented in this article, which were carried out within the development of an item generator for the automatic generation of figural matrices items. The focus of the presented studies was to compare two types of item designs with regard to the effect of variations of the property ''perceptual…

Just as body symmetry reveals developmental stability at the morphological level, general intelligence may reveal developmental stability at the level of brain development and cognitive functioning. These two forms of developmental stability may overlap by tapping into a ''general fitness factor.'' If so, then intellectual tests with higher…

This study examined shared environmental influences on the longitudinal stability of general cognitive ability, as mediated by socioeconomic status and chaos in the home, using 287 pairs of elementary school-age twins drawn from the Western Reserve Reading Project (WRRP). General cognitive ability was evaluated at two annual assessments using the…

Presents an alternative theoretical analysis of several analyses presented by R. Sternberg and his colleagues of studies designed to validate the Sternberg Triarchic Abilities Test. Makes the case that "g" theory is required to understand the relationships obtained by Sternberg and his colleagues. (SLD)

Responds to issues raised by R. Sternberg in his response to commentary on the Sternberg Triarchic Abilities Test. Presents a synopsis of the conclusions that should have been derived from data obtained by Sternberg and his colleagues about the construct validity of the measure. (SLD)

Discusses the research program construct validating the triarchic theory of successful intelligence and discusses objections raised to the triarchic theory and the criticisms of L. Gottfredson. (SLD)