| 1. |
- Byrne, Brian, et al.
(författare)
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Longitudinal twin study of early literacy development : Preschool through Grade 1
- 2007
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Ingår i: Reading and writing. - : Springer Science and Business Media LLC. - 0922-4777 .- 1573-0905. ; 20:1-2, s. 77-102
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Tidskriftsartikel (refereegranskat)abstract
- Grade 1 literacy skills of twin children in Australia (New South Wales) and the United States (Colorado) were explored in a genetically sensitive design (N = 319 pairs). Analyses indicated strong genetic influence on word and nonword identification, reading comprehension, and spelling. Rapid naming showed more modest, though reliable, genetic influence. Phonological awareness was subject to high nonshared environment and no reliable genetic effects, and individual measures of memory and learning were also less affected by genes than nonshared environment. Multivariate analyses showed that the same genes affected word identification, reading comprehension, and spelling. Country comparisons indicated that the patterns of genetic influence on reading and spelling in Grade 1 were similar, though for the U.S. but not the Australian children new genes came on stream in the move from kindergarten to Grade 1. We suggest that this is because the more intensive kindergarten literacy curriculum in New South Wales compared with Colorado, consistent with the mean differences between the two countries, means that more of the genes are "online" sooner in Australia because of accelerated overall reading development. © Springer Science+Business Media B.V. 2007.
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| 2. |
- Samuelsson, Stefan, et al.
(författare)
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Genetic and environmental influences on prereading skills and early reading and spelling development in the United States, Australia, and Scandinavia
- 2007
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Ingår i: Reading and writing. - : Springer Science and Business Media LLC. - 0922-4777 .- 1573-0905. ; 20:1-2, s. 51-75
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Tidskriftsartikel (refereegranskat)abstract
- Genetic and environmental influences on prereading skills in preschool and on early reading and spelling development at the end of kindergarten were compared among samples of identical and fraternal twins from the U.S. (Colorado), Australia, and Scandinavia. Mean comparisons revealed significantly lower preschool print knowledge in Scandinavia, consistent with the relatively lower amount of shared book reading and letter-based activities with parents, and lack of emphasis on print knowledge in Scandinavian preschools. The patterns of correlations between all preschool environment measures and prereading skills within the samples were remarkably similar, as were the patterns of genetic, shared environment, and non-shared environment estimates: in all samples, genetic influence was substantial and shared environment influence was relatively weak for phonological awareness, rapid naming, and verbal memory, genetic influence was weak, and shared environment influence was relatively strong for vocabulary and print knowledge. In contrast, for reading and spelling assessed at the end of kindergarten in the Australian and U.S. samples, there was some preliminary evidence for country differences in the magnitude of genetic and environmental influences. We argue that the apparently higher genetic and lower shared environment influence in the Australian sample was related to a greater emphasis on formal reading instruction, resulting in more advanced reading and spelling skills at the end of kindergarten, and thus there was greater opportunity to observe genetic influences on response to systematic reading instruction among the Australian twins. © Springer Science+Business Media B.V. 2007.
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| 3. |
- Willcutt, Eric, et al.
(författare)
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Preschool twin study of the relation between attention-deficit/ hyperactivity disorder and prereading skills
- 2007
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Ingår i: Reading and writing. - : Springer Science and Business Media LLC. - 0922-4777 .- 1573-0905. ; 20:1-2, s. 103-125
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies have examined the etiology of the association between reading difficulties and attention-deficit hyperactivity disorder (ADHD) in school-age children, but little is known about the relation between prereading skills and ADHD behaviors prior to the beginning of formal reading instruction. A population-based sample of 809 pairs of preschool twins completed an extensive battery of prereading measures, and the parent of each twin completed an ADHD rating scale. Phenotypic analyses revealed small but significant correlations between DSM-IV inattention ratings and six prereading composite measures, whereas hyperactivity-impulsivity symptoms were not independently associated with any of the prereading scores. Multivariate twin analyses indicated that virtually all of the phenotypic correlation between inattention and prereading performance is attributable to common genetic influences, consistent with results obtained in studies of older twins. Although additional research is needed to test alternative causal models in children younger than five years old, these results are most consistent with the hypothesis that reading difficulties and inattention symptoms are attributable to common genetic influences. © Springer Science+Business Media B.V. 2007.
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