Background: Within cohorts of children with autism spectrum disorder (ASD) there is considerable variation in terms of language ability. In the past, it was believed that children with ASD either had delayed articulation and phonology skills or excelled in those areas compared to other language domains. Very little is known about speech sound…

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…

We investigated time-related patterns in levels of cognitive performance during the period from 1970 to 1993 based on data from Swedish draft boards. The conscripts, including more than a million 18-19-year old men, had taken one of two versions of the Swedish enlistment battery (SEB67; 1970-1979 or SEB80; 1980-1993), each composed of four…

Deferred imitation and early social communication skills were compared among speaking and nonspeaking children with autism and children developing typically. Overall, the children with autism showed a lower frequency on measures of deferred imitation and social communication compared with typically developing children. Deferred imitation was…

Irrespective of the grading system, grades are the most valid instrument for predicting educational success. Previous studies have shown that criterion-referenced compulsory school grades are multidimensional, reflecting subject-specific dimensions and a common grade dimension, both of which contribute to the predictive validity of grades. This…

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…

The Matthew effect is often used as a metaphor to describe a widening gap between good and poor readers over time. In this study we examined the development of individual differences in reading and cognitive functioning in children with reading difficulties and normal readers from Grades 1 to 3. Matthew effects were observed for individual…

The importance of cognitive and language skills on reading and spelling development were investigated in a cross-linguistic longitudinal study of 737 English-speaking children (US/Australia) and 169 Scandinavian children (Norway/Sweden) from preschool to Kindergarten and Grade 1. The results revealed that phonological awareness and print knowledge…

A follow-up study was performed to investigate the stability of IQ measures in a group of dyslexic teenagers and young adults. Earlier research had shown contradictory results. The 65 subjects, 12 years old on the average at first test, were retested after a mean interval of six and a half years. There was a significant relative decrease in…

Using data from the Swedish Individual Statistics Project, changes in intelligence among 13-year olds are documented over a 25-year period. The average spatial and reasoning intelligence has risen successively. A clear increase is found for verbal intelligence in the 1960s, with more irregular growth since then. (SLD)

Swedish high school students (n=111) at 3 levels of verbal skill rated their own recall (prediction accuracy) and comprehension (calibration accuracy) of 3 expository texts. Students seemed to assess their own skills well and had acceptable levels of comprehension calibration and recall prediction accuracy. (SLD)

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…