| 1. |
- Byrne, Brian, et al.
(författare)
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Genetic and environmental influences on aspects of literacy and language in early childhood : Continuity and change from preschool to Grade 2
- 2009
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Ingår i: JOURNAL OF NEUROLINGUISTICS. - : Elsevier BV. - 0911-6044. ; 22:3, s. 219-236
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Tidskriftsartikel (refereegranskat)abstract
- Early literacy and language skills of twin children in the USA, Australia, and Scandinavia were explored in a genetically sensitive design (maximum N = 615 pairs). For this article, we report aspects of preschool and Grade 2 data. In Grade 2, there were strong genetic influences on word reading, reading comprehension, and spelling. Vocabulary was about equally affected by genes and shared environment. Multivariate analyses indicated substantial genetic overlap among the Grade 2 literacy variables. Longitudinal analyses showed that genetic factors evident at the preschool stage continued to affect literacy and vocabulary three years later in Grade 2, but there was also evidence of new genetic factors coming into play over the time interval, at least for literacy. Suggestions are made about the search for underlying biological and cognitive processes, and educational implications are explored.
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| 2. |
- Byrne, Brian, et al.
(författare)
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Teacher Effects in Early Literacy Development: Evidence From a Study of Twins
- 2010
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Ingår i: Journal of Educational Psychology. - : Apa American Psychological Association. - 0022-0663 .- 1939-2176. ; 102:1, s. 32-42
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Tidskriftsartikel (refereegranskat)abstract
- It is often assumed that differences in teacher characteristics area major source of variability in childrens educational achievements. We examine this assumption for early literacy achievement by calculating the correlations between pairs of twin children who either shared or did not share a teacher in kindergarten, Grade 1, and Grade 2. Teacher effects-or, more strictly, classroom effects-would show up as higher correlations for same-class than for different-class twin pairs. Same-class correlations were generally higher than different-class correlations.. though not significantly so on most occasions. On the basis of the results, we estimate that the maximum variance accounted for by being assigned to the same or different classrooms is 8%. This is an upper-bound figure for a teacher effect because factors other than teachers may contribute to variation attributable to classroom assignment. We discuss the limitations of the study and draw out some of its educational implications.
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| 3. |
- Ebejer, Jane L., et al.
(författare)
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Genetic and Environmental Influences on Inattention, Hyperactivity-Impulsivity, and Reading: Kindergarten to Grade 2
- 2010
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Ingår i: Scientific Studies of Reading. - : Taylor and Francis. - 1088-8438 .- 1532-799X. ; 14:4, s. 293-316
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Tidskriftsartikel (refereegranskat)abstract
- Twin children from Australia, Scandinavia, and the United States were assessed for inattention, hyperactivity-impulsivity, and reading across the first 3 school years. Univariate behavior-genetic analyses indicated substantial heritability for all three variables in all years. Longitudinal analyses showed one genetic source operating across the time span and a second entering in the second school year for each variable, though possibly not reliable for inattention. Other analyses confirmed previous findings of pleiotropy (shared genes) between inattention and reading and showed that this genetic overlap is in place from kindergarten onwards and is restricted to one of the genetic sources that affect reading and inattention. The results extend previous conclusions about the developmental trajectories of inattention, hyperactivity-impulsivity, and reading and their relationships. Limitations of this study are discussed, as are educational implications.
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| 4. |
- Livingstone, Luisa T., et al.
(författare)
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Does the Environment Have an Enduring Effect on ADHD? A Longitudinal Study of Monozygotic Twin Differences in Children
- 2016
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Ingår i: Journal of Abnormal Child Psychology. - : SPRINGER/PLENUM PUBLISHERS. - 0091-0627 .- 1573-2835. ; 44:8, s. 1487-1501
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Tidskriftsartikel (refereegranskat)abstract
- Environmental factors play a key role in the development of Attention-Deficit/Hyperactivity Disorder (ADHD), but the long-term effects of these factors are still unclear. This study analyses data from 1024 monozygotic (identical) twins in Australia, the United States, and Scandinavia who were assessed for ADHD in Preschool, Kindergarten, Grade 1, and Grade 2. Differences within each twin pair were used as a direct measure of non-shared environmental effects. The Trait-State-Occasion (TSO) model developed by Cole et al. (Psychological Methods, 10, 3-20, 2005) was used to separate the non-shared environmental effects into stable factors, and transient factors that excluded measurement error. Stable factors explained, on average, 44 % and 39 % of the environmental variance in hyperactive-impulsive and inattentive symptoms, respectively. Transient effects explained the remaining 56 % and 60 % of variance. The proportion of stable variance was higher than expected based on previous research, suggesting promise for targeted interventions if future research identifies these stable risk factors.
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| 5. |
- MacDonald, Beatriz, et al.
(författare)
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Cross-Country Differences in Parental Reporting of Symptoms of ADHD
- 2019
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Ingår i: Journal of Cross-Cultural Psychology. - : Sage Publications. - 0022-0221 .- 1552-5422. ; 50:6, s. 806-824
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies within the United States suggest there are cultural and contextual influences on how attention-deficit/hyperactivity disorder (ADHD) symptoms are perceived. If such influences operate within a single country, they are likely to also occur between countries. In the current study, we tested whether country differences in mean ADHD scores also reflect cultural and contextual differences, as opposed to actual etiological differences. The sample for the present study included 974 participants from four countries tested at two time points, the end of preschool and the end of second grade. Consistent with previous research, we found lower mean ADHD scores in Norway and Sweden in comparison with Australia and the United States, and we tested four explanations for these country differences: (a) genuine etiological differences, (b) slower introduction to formal academic skills in Norway and Sweden than in the United States and Australia that indicated a context difference, (c) underreporting tendency in Norway and Sweden, or (d) overreporting tendency in the United States and Australia. Either under- or overreporting would be examples of cultural differences in the perception of ADHD symptoms. Of these explanations, results of ADHD measurement equivalence tests across countries rejected the first three explanations and supported the fourth explanation: an overreporting tendency in the United States and Australia. These findings indicate that parental reporting of ADHD symptoms is more accurate in Norway and Sweden than in Australia and the United States, and, thus, have important clinical and educational implications for how parental reporting informs an ADHD diagnosis in these countries.
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| 6. |
- Miller, Amanda C, et al.
(författare)
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Reading Comprehension in Children with ADHD: Cognitive Underpinnings of the Centrality Deficit
- 2013
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Ingår i: Journal of Abnormal Child Psychology. - : Springer Verlag (Germany). - 0091-0627 .- 1573-2835. ; 41:3, s. 473-483
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Tidskriftsartikel (refereegranskat)abstract
- We examined reading comprehension in children with ADHD by assessing their ability to build a coherent mental representation that allows them to recall central and peripheral information. We compared children with ADHD (mean age 9.78) to word reading-matched controls (mean age 9.89) on their ability to retell a passage. We found that even though children with ADHD recalled more central than peripheral information, they showed their greatest deficit, relative to controls, on central information-a centrality deficit (Miller and Keenan, Annals of Dyslexia 59:99-113, 2009). We explored the cognitive underpinnings of this deficit using regressions to compare how well cognitive factors (working memory, inhibition, processing speed, and IQ) predicted the ability to recall central information, after controlling for word reading ability, and whether these cognitive factors interacted with ADHD symptoms. Working memory accounted for the most unique variance. Although previous evidence for reading comprehension difficulties in children with ADHD have been mixed, this study suggests that even when word reading ability is controlled, children with ADHD have difficulty building a coherent mental representation, and this difficulty is likely related to deficits in working memory.
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| 7. |
- Olson, Richard, et al.
(författare)
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Genetic and Environmental Influences on Vocabulary and Reading Development
- 2011
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Ingår i: SCIENTIFIC STUDIES OF READING. - : Taylor and Francis. - 1088-8438 .- 1532-799X. ; 15:1, s. 26-46
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Tidskriftsartikel (refereegranskat)abstract
- Genetic and environmental relations between vocabulary and reading skills were explored longitudinally from preschool through Grades 2 and 4. At preschool there were strong shared-environment and weak genetic influences on both vocabulary and print knowledge but substantial differences in their source. Separation of etiology for vocabulary and reading continued for word recognition and decoding through Grade 4, but genetic and environmental correlations between vocabulary and reading comprehension approached unity by Grade 4, when vocabulary and word recognition accounted for all of the genetic and shared environment influences on reading comprehension.
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| 8. |
- Samuelsson, Stefan, et al.
(författare)
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Response to early literacy instruction in the United States, Australia, and Scandinavia : A behavioral-genetic analysis
- 2008
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Ingår i: Learning and individual differences. - : Elsevier BV. - 1041-6080 .- 1873-3425. ; 18:3, s. 289-295
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Tidskriftsartikel (refereegranskat)abstract
- Genetic and environmental influences on early reading and spelling at the end of kindergarten and Grade 1 were compared across three twin samples tested in the United States, Australia, and Scandinavia. Proportions of variance due to genetic influences on kindergarten reading were estimated at .84 in Australia, .68 in the U.S., and .33 in Scandinavia. The effects of shared environment on kindergarten reading were estimated at .09 in Australia, .25 in the U.S., and .52 in Scandinavia. A similar pattern of genetic and environmental influences was obtained for kindergarten spelling. One year later when twins in all three samples had received formal literacy instruction for at least one full school year, heritability was similarly high across country, with estimated genetic influences varying between .79 and .83 for reading and between .62 and .79 for spelling. These findings indicate that the pattern of genetic and environmental influences on early reading and spelling development varies according to educational context, with genetic influence increasing as a function of increasing intensity of early instruction. Longitudinal analyses revealed genetic continuity for both reading and spelling between kindergarten and Grade 1 across country. However, a new genetic factor comes into play accounting for independent variance in reading at Grade 1 in the U.S. and Scandinavia, suggesting a change in genetic influences on reading. Implications for response-to-instruction are discussed.
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