This study considered how far nonverbal cognitive, language and reading abilities are affected by common genetic influences in a sample of 312 typically developing Chinese twin pairs aged from 3 to 11 years. Children were individually given tasks of Chinese word reading, receptive vocabulary, phonological memory, tone awareness, syllable and rhyme…

Visuo-spatial reasoning tests, such as Raven's matrices, Cattell's culture-fair test, or various subtests of the Wechsler scales, are frequently used to estimate intelligence scores in the context of inter-racial comparisons. This has led to several high-profile works claiming that certain ethnic groups have lower intelligence than others,…

It is now possible to create individual-specific genetic scores, called genome-wide polygenic scores (GPS). We used a GPS for years of education ("EduYears") to predict reading performance assessed at UK National Curriculum Key Stages 1 (age 7), 2 (age 12) and 3 (age 14) and on reading tests administered at ages 7 and 12 in a UK sample…

Purpose: Multiple factors impact reading acquisition in individuals with reading disability, including genetic disorders such as Williams syndrome (WS). Despite a relative strength in oral language, individuals with WS usually have an intellectual disability and tend to display deficits in areas associated with reading. There is substantial…

In 19 (sub)samples from seven countries (United States, Austria, Germany, Costa Rica, Ecuador, Vietnam, Brazil), we analyzed the impact of parental education compared with wealth on the cognitive ability of children (aged 4-22 years, total N = 15,297). The background of their families ranged from poor indigenous remote villagers to academic…

Little evidence supports that siblings with autism exhibit the same behaviors; however, some findings suggest that level of functioning shows familial aggregation. We tested this notion among multiplex families participating with the Autism Genetic Resource Exchange (AGRE) Consortium, using scores on the "Peabody Picture Vocabulary Test-Third…

The comparison of cognitive and linguistic skills in individuals with developmental disorders is fraught with methodological and psychometric difficulties. In this paper, we illustrate some of these issues by comparing the receptive vocabulary knowledge and non-verbal reasoning abilities of 41 children with Williams syndrome, a genetic disorder in…

Author focused on differences between whites and negroes in the United States and more generally on racial variation in man. (Author/RK)

Sleep plays an active role in memory consolidation. Because children with Down syndrome (DS) and Williams syndrome (WS) experience significant problems with sleep and also with learning, we predicted that sleep-dependent memory consolidation would be impaired in these children when compared to typically developing (TD) children. This is the first…

This study followed the development of reading speed, reading accuracy, and spelling in transparent Finnish orthography in children through Grades 2, 3, and 8. We compared 2 groups of children with familial risk for dyslexia--1 group with dyslexia (Dys _FR, n = 35) and 1 group without (NoDys_FR, n = 66) in Grade 2--with a group of children without…

Previous studies suggest that individuals with Williams syndrome (WS), a rare genetically based neurodevelopmental disorder, show specific weaknesses in visual attention and response inhibition within the visuospatial domain. Here we examine the extent to which impairments in attentional control extend to the visuomotor domain using a…

Mothers were asked to predict their children's responses to standardized intelligence test items. Negative correlation was expected between inaccurate maternal knowledge of children's ability and degree of children's psychological development. False maternal predictions correlated - .80 with correct children's responses. Nearly all of the…