Studies investigating evolutionary theories on the origins of national differences in intelligence have been criticized on the basis that both national cognitive ability measures and supposedly evolutionarily informative proxies (such as latitude and climate) are confounded with general developmental status. In this study 14 Y chromosomal…

The present study was intended to provide perspective, albeit less than unequivocal, on the research of Lynn (2010) who reported higher IQs in the northern than southern Italian regions. He attributes this to northern Italians having a greater genetic similarity to middle Europeans and southern Italians to Mediterranean people. Higher regional IQ…

Multitasking performance is relevant in everyday life and job analyses highlight the influence of multitasking over several diverse occupations. Intelligence is the best single predictor of overall job performance and it is also related to individual differences in multitasking. However, it has been shown that working memory capacity (WMC) is…

Aging patterns in WAIS-R Block Design Test (BDT) were examined cross-sectionally and longitudinally. One sample (35-80 years, n=1000) was assessed in 1988-1990 and five years later (836 returned). An independent cohort-matched sample (n=974) was assessed at Time 2 to control for practice effects. Relations between BDT, gender, and education were…

Genetic influence was estimated on Wechsler Intelligence Scale for Children subtests from inbreeding depression scores calculated on cousin marriages in Japan (n=1,854 children) and correlated with American Black-White racial differences. The genetic contribution of racial differences in cognitive performance may be more robust than was previously…

Working memory (WM) has been associated with the acquisition of arithmetic skills, however, the components of WM that underlie this acquisition have not been explored. This study explored the contribution of two WM systems (the phonological loop and the central executive) to mathematical performance in young children. The results showed that a…

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.…

The purpose of this study is threefold. First, an estimate of state IQ is derived and its strengths and limitations are considered. To that end, an indicator of downward bias in estimating state IQ is provided. Two preliminary causal models are offered that predict state IQ. These models were found to be highly predictive of state IQ, yielding…

This editorial proposes that the dependent variables that predict childhood intelligence quotient (IQ) from habituation and recognition memory assessments made during infancy may primarily reflect individual differences in rate of information processing. Inhibition may be a stable thread in mental development. (Author/SLD)

Deviations in children's mental test performance were studied for children of 169 disadvantaged mothers at 24, 48, and 96 months to determine whether aspects of the child rearing environment predicted the deviations from expected values. Relationships between aspects of the environment, child intelligence, and child characteristics are discussed.…

Sex-related differential studies on mathematical abilities have hardly taken into account the mediator role of the verbal factor, which contrasts with the interest shown in the mediator role of visuospatial aptitude. We predicted that if sex-related differences were found, mental rotation would mediate mathematical abilities typically favoring…

It has been suggested that IQ's of gifted children resemble parents less than do people in general. This finding may have been an artifact of the particular estimator of the regression coefficient used. An unbiased estimator is introduced and shows that gifted children resemble parents more than persons in general. (Author/RD)

Meta-analysis of 225 hypothesis tests of measures of memory for order (MFO) and the relationship of MFO and measures of general ability demonstrate a significant relationship between MFO and standardized test scores. Fifty-one independent samples were tested. MFO task quality was a significant predictor of effect size. (SLD)

Emotional intelligence (EI) has often been criticized to measure nothing more than intelligence and personality. Recent studies have shown that EI has an incremental validity concerning life outcome criteria, but inconsistent results have been found for achievement criteria. Two studies were conducted to examine if EI could predict achievement…

Genetic and environmental etiologies of individual differences in tests of intelligence and school achievement were investigated in a study from the Colorado Adoption Project. A multivariate conditional path model was fitted to general cognitive ability and reading performance data from 119 adoptive and 120 nonadoptive families. (SLD)