Background: Children's numerical and arithmetic skills differ greatly already at an early age. Although research focusing on accounting for these large individual differences clearly demonstrates that mathematical performance draws upon several cognitive abilities, our knowledge concerning key abilities underlying mathematical skill development is…

Aging-related declines occur in many different domains of cognitive function during middle and late adulthood. However, whether a global dimension underlies individual differences in changes in different domains of cognition and whether global genetic influences on cognitive changes exist is less clear. We addressed these issues by applying…

There is uncertainty about the proportion of children with autism spectrum disorders who do not develop phrase speech during the preschool years. The main purpose of this study was to examine this ratio in a population-based community sample of children. The cohort consisted of 165 children (141 boys, 24 girls) with autism spectrum disorders aged…

Previous analyses have identified a genetic contribution to the correlation between declines with age in processing speed and higher cognitive abilities. The goal of the current analysis was to apply the biometric dual change score model to consider the possibility of temporal dynamics underlying the genetic covariance between aging trajectories…

A study of the reading competence of 25 visually impaired pupils in Sweden followed subjects from 1988 to 1991. Neither visual acuity, reading media, optical aids, nor reading distance were clearly related to reading competence. Rather, good readers were students who scored higher on verbal cognitive tests and had a greater interest in reading as…

Collected data on twins' performance on 13 cognitive variables measured three times at three-year intervals. Twins were monozygotic or dizygotic pairs reared together or apart and were in six cohorts ranging in age from 41 through 84 years. Found stable mean cognitive performance across time on eight measures for the younger cohorts, and…

In a sample of 92 children aged 6-13 years this study investigates the normal developmental change in the relation between executive functioning (EF) and the core behavioural symptoms associated with attention deficit hyperactivity disorder (ADHD) (hyperactivity/impulsivity and inattention) as well as symptoms often co-occurring with childhood…

Assessed the quality of home and out-of-home care environments, child temperament, and the development of verbal abilities among infants at 18 months and then at 8 years of age. Found that both tested and rated cognitive abilities at age 8 were related to earlier measures of verbal ability and to paternal involvement during preschool years. (MOK)

This study investigated possible changes in verbal, spatial, and reasoning intelligence in Swedish 13-year-olds over a 20-year period. The first sample included about 12,000 students born in 1948. Data consisted of (1) information from school records, (2) information on personal background, (3) scores on three intelligence tests and three…