Lynn (2010a, 2010b) argued that individuals from south Italy have a lower IQ than individuals from north Italy, and that these differences in IQ are at the basis of north-south gap in income, education, infant mortality, stature, and literacy. In the present paper, we discuss several theoretical and methodological aspects which we regard as flaws…

The genetic and environmental origins of individual differences in mathematical self-evaluation over time and its association with later mathematics achievement were investigated in a UK sample of 2138 twin pairs at ages 9 and 12. Self-evaluation indexed how good children think they are at mathematical activities and how much they like those…

Few studies have identified individual differences in vocational knowledge or its association with career aspirations or expectations of children. We investigated whether individual differences in grade, gender, academic achievement, and SES predict levels of vocational knowledge, and further examined the relationship between vocational knowledge…

The current study examined individual differences in children's phonological and visuospatial short-term memory as potential mediators of the relationship among attention problems and near- and long-term scholastic achievement. Nested structural equation models revealed that teacher-reported attention problems were associated negatively with…

Lateralization of the brain is strongly influenced by prenatal androgens, with differential exposure thought to account for cognitive sex differences. This study investigated sex and individual differences and relationships between 2D:4D (the ratio of the 2nd to 4th digit [digit ratio] as a proxy indicator of prenatal testosterone exposure),…

This study is an item analysis of the Matching Familiar Figures Test-20. We examined error scores in the Matching Familiar Figures Test-20 to determine the influence of the difficulty of the test on the assessment of reflection-impulsivity. The sample included 700 participants aged between 6 and 12 years. The results obtained from the corrected…

Creativity can be broadly defined as a combination of interacting individual and environmental resources leading to the production of valuable solutions. This paper concentrates on the type of creativity that can be expressed in solving social problems. After reviewing the potentially relevant psychological and contextual variables intervening in…

In a longitudinal genetic study we explored which factors underlie stability in verbal and nonverbal abilities, and the extent to which the association between these abilities becomes stronger as children grow older. Measures of verbal and nonverbal IQ were collected in Dutch twin pairs at age 5, 7, 10, 12 and 18 years. The stability of both…