What's the Problem? Familiarity Working Memory, and Transfer in a Problem-Solving Task.

The contributions of familiarity and working memory to transfer were examined in the Tower of Hanoi task. Participants completed 3 different versions of the task: a standard 3-disk version, a clothing exchange task that included familiar semantic content, and a tea ceremony task that included unfamiliar semantic content. The constraints on moves were equivalent across tasks, and each could be solved with the same sequence of movements. Working memory demands were manipulated by the provision of a (static or dynamic) visual representation of the problem. Performance was equivalent for the standard Tower of Hanoi and clothing exchange tasks but worse for the tea ceremony task, and it decreased with increasing working memory demands. Furthermore, the standard Tower of Hanoi task and clothing exchange tasks independently, additively, and equivalently transferred to subsequent tasks, whereas the tea ceremony task did not. The results suggest that both familiarity and working memory demands determine overall level of performance, whereas familiarity influences transfer.

The SWAN captures variance at the negative and positive ends of the ADHD symptom dimension.

OBJECTIVE: The Strengths and Weaknesses of ADHD Symptoms and Normal Behavior (SWAN) Rating Scale differs from previous parent reports of ADHD in that it was designed to also measure variability at the positive end of the symptom spectrum. METHOD: The psychometric properties of the SWAN were tested and compared with an established measure of ADHD, the Disruptive Behavior Rating Scale (DBRS). RESULTS: The SWAN demonstrates comparable validity, reliability, and heritability to the DBRS. Furthermore, plots of the SWAN and DBRS reveal heteroscedasticity, which supports the SWAN as a preferred measure of positive attention and impulse regulation behaviors. CONCLUSION: The ability of the SWAN to measure additional variance at the adaptive end of the ADHD symptom dimensions makes it a promising tool for behavioral genetic studies of ADHD.

Does subtype matter? Assessing the effects of maltreatment on functioning in preadolescent youth in out-of-home care.

OBJECTIVES: Attempts to understand the effects of maltreatment subtypes on childhood functioning are complicated by the fact that children often experience multiple subtypes. This study assessed the effects of maltreatment subtypes on the cognitive, academic, and mental health functioning of preadolescent youth in out-of-home care using both "variable-centered" and "person-centered" statistical analytic approaches to modeling multiple subtypes of maltreatment. METHODS: Participants included 334 preadolescent youth (ages 9-11) placed in out-of-home care due to maltreatment. The occurrence and severity of maltreatment subtypes (physical abuse, sexual abuse, physical neglect, and supervisory neglect) were coded from child welfare records. The relationships between maltreatment subtypes and children's cognitive, academic, and mental health functioning were evaluated with the following approaches: (1) "Variable-centered" analytic methods: a. Regression approach: Multiple regression was used to estimate the effects of each maltreatment subtype (separate analyses for occurrence and severity), controlling for the other subtypes. b. Hierarchical approach: Contrast coding was used in regression analyses to estimate the effects of discrete maltreatment categories that were assigned based on a subtype occurrence hierarchy (sexual abuse > physical abuse > physical neglect > supervisory neglect). (2) "Person-centered" analytic method: Latent class analysis was used to group children with similar maltreatment severity profiles into discrete classes. The classes were then compared to determine if they differed in terms of their ability to predict functioning. RESULTS: The approaches identified similar relationships between maltreatment subtypes and children's functioning. The most consistent findings indicated that maltreated children who experienced physical or sexual abuse were at highest risk for caregiver-reported externalizing behavior problems, and those who experienced physical abuse and/or physical neglect were more likely to have higher levels of caregiver-reported internalizing problems. Children experiencing predominantly low severity supervisory neglect had relatively better functioning than other maltreated youth. CONCLUSIONS: Many of the maltreatment subtype differences identified within the maltreated sample in the current study are consistent with those from previous research comparing maltreated youth to non-maltreated comparison groups. Results do not support combining supervisory and physical neglect. The "variable-centered" and "person-centered" analytic approaches produced complementary results. Advantages and disadvantages of each approach are discussed.

Individual prediction of dyslexia by single versus multiple deficit models.

The overall goals of this study were to test single versus multiple cognitive deficit models of dyslexia (reading disability) at the level of individual cases and to determine the clinical utility of these models for prediction and diagnosis of dyslexia. To accomplish these goals, we tested five cognitive models of dyslexia--two single-deficit models, two multiple-deficit models, and one hybrid model--in two large population-based samples, one cross-sectional (Colorado Learning Disability Research Center) and one longitudinal (International longitudinal Twin Study). The cognitive deficits included in these cognitive models were in phonological awareness, language skill, and processing speed and/or naming speed. To determine whether an individual case fit one of these models, we used two methods: 1) the presence or absence of the predicted cognitive deficits, and 2) whether the individual's level of reading skill best fit the regression equation with the relevant cognitive predictors (i.e., whether their reading skill was proportional to those cognitive predictors.) We found that roughly equal proportions of cases met both tests of model fit for the multiple deficit models (30-36%) and single deficit models (24-28%); hence, the hybrid model provided the best overall fit to the data. The remaining roughly 40% of cases in each sample lacked the deficit or deficits that corresponded with their best-fitting regression model. We discuss the clinical implications of these results for both diagnosis of school-age children and preschool prediction of children at risk for dyslexia.

Phonological Spelling and Reading Deficits in Children with Spelling Disabilities.

Spelling errors in the Wide Range Achievement Test were analyzed for 77 pairs of children, each of which included one older child with spelling disability (SD) and one spelling-level-matched younger child with normal spelling ability from the Colorado Learning Disabilities Research Center database. Spelling error analysis consisted of a percent graphotactic-accuracy (GA) score based on syllable position and existence in English, and a phonological accuracy score (PA). The SD group scored significantly worse in the PA measure, and non-significantly better than controls on the GA measure. The group by measure interaction was significant. Spelling matched pairs had very similar scores for word recognition and orthographic coding, but the SD group exhibited significant deficits in reading measures of phonological decoding and in language measures of phonological awareness.

Heritability of high reading ability and its interaction with parental education.

Moderation of the level of genetic influence on children's high reading ability by environmental influences associated with parental education was explored in two independent samples of identical and fraternal twins from the United States and Great Britain. For both samples, the heritability of high reading performance increased significantly with lower levels of parental education. Thus, resilience (high reading ability despite lower environmental support) is more strongly influenced by genotype than is high reading ability with higher environmental support. This result provides a coherent account when considered alongside results of previous research showing that heritability for low reading ability decreased with lower levels of parental education.

Gene X environment interactions in reading disability and attention-deficit/hyperactivity disorder.

This article examines Gene x Environment (G x E) interactions in two comorbid developmental disorders--reading disability (RD) and attention-deficit/hyperactivity disorder (ADHD)--as a window on broader issues on G x E interactions in developmental psychology. The authors first briefly review types of G x E interactions, methods for detecting them, and challenges researchers confront in interpreting such interactions. They then review previous evidence for G x E interactions in RD and ADHD, the directions of which are opposite to each other: bioecological for RD and diathesis stress for ADHD. Given these results, the authors formulate and test predictions about G x E interactions that would be expected at the favorable end of each symptom dimension (e.g., above-average reading or attention). Consistent with their prediction, the authors found initial evidence for a resilience interaction for above-average reading: higher heritability in the presence of lower parental education. However, they did not find a G x E interaction at the favorable end of the ADHD symptom dimension. The authors conclude with implications for future research.

Parental education moderates genetic influences on reading disability.

Environmental moderation of the level of genetic influence on children's reading disabilities was explored in a sample of 545 identical and fraternal twins (mean age = 11.5 years). Parents' number of years of education, which is correlated with a broad range of environmental factors related to reading development, was significantly related to the level of genetic influence on reading disability. Genetic influence was higher and environmental influence was lower among children whose parents had a high level of education, compared with children whose parents had a lower level of education. We discuss the implications of these results for behavior genetic and molecular genetic research, for the diagnosis and remediation of reading disabilities, and for policy in public education.

Genetic and environmental influences on word recognition and spelling deficits as a function of age.

Previous twin studies have suggested a possible developmental dissociation between genetic influences on word recognition and spelling deficits, wherein genetic influence declined across age for word recognition, and increased for spelling recognition. The present study included two measures of word recognition (timed, untimed) and two measures of spelling (recognition, production) in younger and older twins. The heritability estimates for the two word recognition measures were .65 (timed) and .64 (untimed) in the younger group and .65 and .58 respectively in the older group. For spelling, the corresponding estimates were .57 (recognition) and .51 (production) in the younger group and .65 and .67 in the older group. Although these age group differences were not significant, the pattern of decline in heritability across age for reading and increase for spelling conformed to that predicted by the developmental dissociation hypothesis. However, the tests for an interaction between genetic influences on word recognition and spelling deficits as a function of age were not significant.