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Direct linkWakeman, Holly N.; Wadsworth, Sally J.; Olson, Richard K.; DeFries, John C.; Pennington, Bruce F.; Willcutt, Erik G. – Journal of Learning Disabilities, 2023
This study investigated the relationship between mathematics difficulties and psychopathology in a large community sample (N = 881) of youth (8-18 years of age) in the United States. The primary aims of the study were to (a) test the associations between mathematics difficulties and specific components of internalizing, externalizing, attention,…
Descriptors: Children, Adolescents, Correlation, Learning Problems
Slomowitz, Rebecca F.; Narayan, Angela J.; Pennington, Bruce F.; Olson, Richard K.; DeFries, John C.; Willcutt, Erik G.; McGrath, Lauren M. – Scientific Studies of Reading, 2021
This study examined whether strong cognitive skills (i.e. vocabulary, rapid naming, verbal working memory [VWM], and processing speed [PS]) contributed to resilience in single-word reading skills in children at risk for reading difficulties because of low phonological awareness scores (PA). Promotive factors were identified by main effects and…
Descriptors: Thinking Skills, Reading Skills, Reading Difficulties, Phonological Awareness
Willcutt, Erik G.; McGrath, Lauren M.; Pennington, Bruce F.; Keenan, Janice M.; DeFries, John C.; Olson, Richard K.; Wadsworth, Sally J. – New Directions for Child and Adolescent Development, 2019
Current definitions of specific learning disability (SLD) identify a heterogeneous population that includes individuals with weaknesses in reading, math, or writing, and these academic difficulties often co-occur in many of the same individuals. The Colorado Learning Disabilities Research Center (CLDRC) is an interdisciplinary, multisite research…
Descriptors: Comorbidity, Learning Disabilities, Twins, Reading Difficulties
Christopher, Micaela E.; Hulslander, Jacqueline; Byrne, Brian; Samuelsson, Stefan; Keenan, Janice M.; Pennington, Bruce; DeFries, John C.; Wadsworth, Sally J.; Willcutt, Erik; Olson, Richard K. – Child Development, 2015
The present study explored the environmental and genetic etiologies of the longitudinal relations between prereading skills and reading and spelling. Twin pairs (n = 489) were assessed before kindergarten (M = 4.9 years), post-first grade (M = 7.4 years), and post-fourth grade (M = 10.4 years). Genetic influences on five prereading skills (print…
Descriptors: Genetics, Longitudinal Studies, Reading Comprehension, Environmental Influences
Astrom, Raven L.; Wadsworth, Sally J.; Olson, Richard K.; Willcutt, Erik G.; DeFries, John C. – Learning and Individual Differences, 2012
Reading performance data from 254 pairs of identical (MZ) and 420 pairs of fraternal (DZ) twins, 8.0 to 20.0 years of age, were subjected to multiple regression analyses. An extension of the DeFries-Fulker (DF) analysis (DeFries & Fulker, 1985, 1988) that facilitated inclusion of data from 303 of their nontwin siblings was employed. In addition to…
Descriptors: Reading Difficulties, Twins, Genetics, Environmental Influences
Fujisawa, Keiko K.; Wadsworth, Sally J.; Kakihana, Shinichiro; Olson, Richard K.; DeFries, John C.; Byrne, Brian; Ando, Juko – Learning and Individual Differences, 2013
This first Japanese twin study of early literacy development investigated the extent to which genetic and environmental factors influence individual differences in prereading skills in 238 pairs of twins at 42 months of age. Twin pairs were individually tested on measures of phonological awareness, "kana" letter name/sound knowledge,…
Descriptors: Twins, Preschool Children, Emergent Literacy, Early Reading
Olson, Richard K.; Hulslander, Jacqueline; Christopher, Micaela; Keenan, Janice M.; Wadsworth, Sally J.; Willcutt, Erik G.; Pennington, Bruce F.; DeFries, John C. – Annals of Dyslexia, 2013
Identical and fraternal twins (N = 540, age 8 to 18 years) were tested on three different measures of writing (Woodcock-Johnson III Tests of Achievement--Writing Samples and Writing Fluency; Handwriting Copy from the Group Diagnostic Reading and Aptitude Achievement Tests), three different language skills (phonological awareness, rapid naming, and…
Descriptors: Measurement, Achievement Tests, Genetics, Word Recognition
Willcutt, Erik G.; Petrill, Stephen A.; Wu, Sarah; Boada, Richard; DeFries, John C.; Olson, Richard K.; Pennington, Bruce F. – Journal of Learning Disabilities, 2013
Reading disability (RD) and math disability (MD) frequently co-occur, but the etiology of this comorbidity is not well understood. Groups with RD only (N = 241), MD only (N = 183), and RD + MD (N = 188) and a control group with neither disorder (N = 411) completed a battery of measures of internalizing and externalizing psychopathology, social and…
Descriptors: Comorbidity, Reading Difficulties, Behavior Disorders, Psychopathology
Olson, Richard K.; Keenan, Janice M.; Byrne, Brian; Samuelsson, Stefan; Coventry, William L.; Corley, Robin; Wadsworth, Sally J.; Willcutt, Erik G.; DeFries, John C.; Pennington, Bruce F.; Hulslander, Jacqueline – Scientific Studies of Reading, 2011
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…
Descriptors: Reading Comprehension, Genetics, Word Recognition, Etiology
Hawke, Jesse L.; Olson, Richard K.; Willcut, Erik G.; Wadsworth, Sally J.; DeFries, John C. – Dyslexia, 2009
The prevalence of reading difficulties is typically higher in males than females in both referred and research-identified samples, and the ratio of males to females is greater in more affected samples. To explore possible gender differences in reading performance, we analysed data from 1133 twin pairs in which at least one member of each pair had…
Descriptors: Reading Difficulties, Twins, Females, Incidence
Rhee, Soo Hyun; Willcutt, Erik G.; Hartman, Christie A.; Pennington, Bruce F.; DeFries, John C. – Journal of Abnormal Child Psychology, 2008
There is significant comorbidity between attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD). The conclusions of studies that examined the causes of comorbidity between ADHD and CD conflict, with some researchers finding support for the three independent disorders model and others finding support for the correlated risk…
Descriptors: Attention Deficit Disorders, Hyperactivity, Twins, Risk
Byrne, Brian; Coventry, William L.; Olson, Richard K.; Hulslander, Jacqueline; Wadsworth, Sally; DeFries, John C.; Corley, Robin; Willcutt, Erik G.; Samuelsson, Stefan – Journal of Research in Reading, 2008
As part of a longitudinal twin study of literacy and language, we conducted a behaviour-genetic analysis of orthographic learning, spelling and decoding in Grade 2 children (225 identical and 214 fraternal twin pairs) in the United States and Australia. Each variable showed significant genetic and unique environment influences. Multivariate…
Descriptors: Twins, Spelling, Genetics, Foreign Countries
Samuelsson, Stefan; Byrne, Brian; Olson, Richard K.; Hulslander, Jacqueline; Wadsworth, Sally; Corley, Robin; Willcutt, Erik G.; DeFries, John C. – Learning and Individual Differences, 2008
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 0.84 in Australia, 0.68 in the U.S., and 0.33 in…
Descriptors: Twins, Spelling, Early Reading, Genetics
Friedman, Naomi P.; Miyake, Akira; Young, Susan E.; DeFries, John C.; Corley, Robin P.; Hewitt, John K. – Journal of Experimental Psychology: General, 2008
Recent psychological and neuropsychological research suggests that executive functions--the cognitive control processes that regulate thought and action--are multifaceted and that different types of executive functions are correlated but separable. The present multivariate twin study of 3 executive functions (inhibiting dominant responses,…
Descriptors: Genetics, Metacognition, Memory, Psychology
Hawke, Jesse L.; Wadsworth, Sally J.; Olson, Richard K.; DeFries, John C. – Reading and Writing: An Interdisciplinary Journal, 2007
To test the hypothesis that the etiology of reading difficulties may differ for males and females in more severely impaired samples, reading performance data from monozygotic (MZ), same-sex dizygotic (DZ[subscript ss]), and opposite-sex dizygotic (DZ[subscript os]) twin pairs were analyzed using a model-fitting implementation of the DeFries-Fulker…
Descriptors: Severity (of Disability), Environmental Influences, Etiology, Genetics
