Suchergebnisse

Abstract Prior research suggests shared environmental influences on cognitive performance are important in early childhood. However, few studies have attempted to identify the factors comprising this shared environmental variance. To address this issue, we examined the covariance between task orientation, parental warmth, socioeconomic status and general cognitive ability in a British twin study of 125 pairs of identical and same‐sex fraternal twins. Task orientation correlated r = .41 with general cognitive ability. Bivariate genetic analyses suggested that this correlation was mediated by shared environmental influences. Additional analyses suggested that SES and parental warmth mediated about two‐thirds of the shared environmental covariance between task engagement and cognitive skills.

More than a century ago, Francis Galton, the father of behavioural genetics, coined the scientific use of the phrase nature–nurture. He believed that ability, especially individual differences in intelligence, is due primarily to nature rather than nurture, as implied by the title of his earliest and most famous work,Hereditary Genius(1869). In a paper on twins, he declared that 'there is no escape from the conclusion that nature prevails enormously over nurture' (1875. p. 404).

AbstractA previous publication reported the etiology of mathematics performance in 7-year-old twins (Oliver et al., 2004). As part of the same longitudinal study we investigated low mathematics performance and normal variation in a representative United Kingdom sample of 1713 same-sex 9-year-old twins based on teacher-assessed National Curriculum standards. Univariate individual differences and DeFries-Fulker extremes analyses were performed. Similar to our results at 7 years, all mathematics scores at 9 years showed high heritability (.62–.75) and low shared environmental estimates (.00–.11) for both the low performance group and the full sample. Longitudinal analyses were performed from 7 to 9 years. These longitudinal analyses indicated strong genetic continuity from 7 to 9 years for both low performance and mathematics in the normal range. We conclude that, despite the considerable differences in mathematics curricula from 7 to 9 years, the same genetic effects largely operate at the two ages.

Abstract Change in task persistence was assessed in two annual assessments using teachers', testers', and observers' ratings. Participants included 79 monozygotic and 116 same‐sex dizygotic twin pairs who were in Kindergarten or 1st grade (4.3 to 7.9 years old) at the initial assessment. Task persistence was widely distributed and higher among older children and girls. Overall, there was modest growth in persistence over time, and moderate stability of individual differences. Most of the stability was accounted for by genetic influences, whereas most of the change was accounted for by nonshared environment, including an association with observed differential maternal warm supportive behavior.

Abstract Task persistence, measured by a composite score of independent teacher, tester and observer reports, was examined using behavioral genetic analysis. Participants included 92 monozygotic and 137 same‐sex dizygotic twin pairs in Kindergarten or 1st grade (4.3 to 7.9 years old). Task persistence was widely distributed, higher among older children, positively associated with standardized tests of cognitive performance and achievement, and negatively associated with parents', teachers' and observers' reports of behavioral problems. Cross‐sectional analysis indicated a strong developmental shift from shared environment variance among younger children to additive genetic variance in older children.

AbstractSkilled reading depends on recognizing words efficiently in isolation (word‐level processing; WL) and extracting meaning from text (discourse‐level processing; DL); deficiencies in either result in poor reading. FMRI has revealed consistent overlapping networks in word and passage reading, as well as unique regions for DL processing; however, less is known about how WL and DL processes interact. Here we examined functional connectivity from seed regions derived from where BOLD signal overlapped during word and passage reading in 38 adolescents ranging in reading ability, hypothesizing that even though certain regions support word‐ and higher‐level language, connectivity patterns from overlapping regions would be task modulated. Results indeed revealed that the left‐lateralized semantic and working memory (WM) seed regions showed task‐dependent functional connectivity patterns: during DL processes, semantic and WM nodes all correlated with the left angular gyrus, a region implicated in semantic memory/coherence building. In contrast, during WL, these nodes coordinated with a traditional WL area (left occipitotemporal region). In addition, these WL and DL findings were modulated by decoding and comprehension abilities, respectively, with poorer abilities correlating with decreased connectivity. Findings indicate that key regions may uniquely contribute to multiple levels of reading; we speculate that these connectivity patterns may be especially salient for reading outcomes and intervention response.

AbstractA parental report questionnaire posted to a population sample of 18-month-old twins correctly assigned zygosity in 95%of cases when validated against zygosity determined by identity of polymorphic DNA markers. The questionnaire was as accurate when readministered at 3 years of age, with 96% of children being assigned the same zygosity on both occasions. The results validate the use of parental report questionnaire data to determine zygosity in infancy. Twin Research (2000) 3, 129–133.

Abstract:This study examined maternal and child predictors of White mothers' cultural socialization/pluralism and preparation for bias of Chinese and Korean adopted children in families participating in the Northeast‐Northwest Collaborative Adoption Project. Mother's psychological connection to Asian Americans, but not White identity, and children's age predicted cultural socialization/pluralism and preparation for bias. Birth country was related to cultural socialization/pluralism but not preparation for bias. Cultural socialization/pluralism was related to fewer externalizing problems but not to internalizing problems. Preparation for bias was not related to behavioral problems. The implications of these findings are summarized in terms of interventions aimed at increasing mothers' connections to Asian American communities or individuals, providing Korean cultural information to parents of Korean adoptees, and the timing of interventions.

Differences in mothers' parenting behaviors toward their identical twin preschoolers were examined to identify nonshared environmental processes in social‐emotional development. The study included 62 pairs of 3½‐year‐old same‐sex identical twins. Indicators of each child's social‐emotional development (temperament, prosocial behavior, behavior problems and noncompliance) and parenting environment (warmth and negativity, positive and negative control, responsiveness) were assessed using observers', interviewers', and parents' ratings. Mothers treated their identical twins differently, and this differential treatment covaried in expected ways with identical twin differences in social‐emotional adjustment. The twin who received more supportive and less punitive forms of parenting was also higher in positive mood and prosocial behaviors and lower in negative mood and behavior problems when compared to her or his twin.

AbstractSocioeconomic risks (SES risks) are robust risk factors influencing children's academic development. However, it is unclear whether the effects of SES on academic development operate universally in all children equally or whether they vary differentially in children with particular characteristics. The current study aimed to explore children's temperament as protective or risk factors that potentially moderate the associations between SES risks and academic development. Specifically, latent growth modeling (LGM) was used in two longitudinal datasets with a total of 2236 children to examine how family SES risks and children's temperament interactively predicted the development of reading and math from middle childhood to early adolescence. Results showed that low negative affect, high effortful control, and low surgency mitigated the negative associations between SES risks and both reading and math development in this developmental period. These findings underline the heterogeneous nature of the negative associations between SES risks and academic development and highlight the importance of the interplay between biological and social factors on individual differences in development.