Longitudinal Effects on Early Adolescent Language: A Twin Study.

Purpose: We evaluated genetic and environmental contributions to individual differences in language skills during early adolescence, measured by both language sampling and standardized tests, and examined the extent to which these genetic and environmental effects are stable across time. Method: We used structural equation modeling on latent factors to estimate additive genetic, shared environmental, and nonshared environmental effects on variance in standardized language skills (i.e., Formal Language) and productive language-sample measures (i.e., Productive Language) in a sample of 527 twins across 3 time points (mean ages 10-12 years). Results: Individual differences in the Formal Language factor were influenced primarily by genetic factors at each age, whereas individual differences in the Productive Language factor were primarily due to nonshared environmental influences. For the Formal Language factor, the stability of genetic effects was high across all 3 time points. For the Productive Language factor, nonshared environmental effects showed low but statistically significant stability across adjacent time points. Conclusions: The etiology of language outcomes may differ substantially depending on assessment context. In addition, the potential mechanisms for nonshared environmental influences on language development warrant further investigation.

Impact of prematurity on language skills at school age.

PURPOSE: The existing literature on language outcomes in children born prematurely focuses almost exclusively on standardized test scores rather than discourse-level abilities. The authors of this study looked longitudinally at school-age language outcomes and potential moderating variables for a group of twins born prematurely versus a control group of twins born at full term, analyzing both standardized test results and language sample data from the population-based Western Reserve Reading Project (WRRP; Petrill, Deater-Deckard, Thompson, DeThorne, & Schatschneider, 2006). METHOD: Fifty-seven children born prematurely, at ≤32 weeks or <1,500 g, were compared with 57 children born at full term and were matched for age, gender, race, and parental education. Data included discourse-level language samples and standardized test results, collected at average ages 7, 8, and 10 years. The language samples were analyzed to yield a number of semantic and syntactic measures that were consolidated via factor analysis. RESULTS: Regression models showed significant differences between the 2 groups for standardized test results, although the mean score for both groups fell in the normal range. For the discourse-level language measures, however, differences never reached statistical significance. Parental education was significantly associated with improved standardized test scores. CONCLUSIONS: These findings suggest that in the absence of frank neurological impairment, sophisticated semantic and syntactic skills may be relatively intact in the discourse-level language of children born prematurely. Implications for assessment, particularly the potential role of attention and executive function in standardized testing tasks, are reviewed.

Longitudinal stability in genetic effects on children's conversational language productivity.

PURPOSE: The authors examined the longitudinal stability of genetic and environmental influences on children's productive language sample measures during the early school-age years. METHOD: Twin study methodology with structural equation modeling was used to derive univariate estimates of additive genetic (A), shared environmental (C), and nonshared environmental (E) effects on language measures at each of 2 time points, based on 487 twins at the 1st-grade time point and 387 twins at the 2nd-grade time point. To address questions of stability over time, the authors used longitudinal latent factor analysis. RESULTS: Stability in the Conversational Language factor was accounted for almost entirely by shared genetic effects between 1st and 2nd grade, meaning no new genetic effects were observed at the 2nd time point. In contrast, nonshared environmental effects were entirely time point specific, meaning whatever nonshared environmental influences were operating at the first time point were not influencing individual variation in the language factor at the second time point. CONCLUSION: The discussion in this article centers on possible candidates for both genetic and nonshared environmental effects as well as implications for clinical practice and future research.

Volubility as a mediator in the associations between conversational language measures and child temperament.

BACKGROUND: Despite support for the use of conversational language measures, concerns remain regarding the extent to which they may be confounded with aspects of child temperament, extraversion in particular. AIMS: This study of 161 twins from the Western Reserve Reading Project (WRRP) examined the associations between children's conversational language use and three key aspects of child temperament: Surgency (i.e., introversion/extraversion), Effortful Control (i.e., attention and task persistence) and Negative Affectivity (e.g., fear, anger, sadness). Child biological sex was considered as a possible moderating factor. METHODS & PROCEDURES: Correlational analyses were conducted between aspects of temperament during early school-age years (i.e., 7-8 years), as measured by the Children's Behavior Questionnaire-Short Form (CBQ), and six different measures of children's conversational language use: total number of complete and intelligible utterances (TCICU), number of total words (NTW), mean length of utterance (MLU), total number of conjunctions (TNC), number of different words (NDW) and measure D (i.e., a measure of lexical diversity). Values for NTW, TNC and NDW were derived both on the entire sample and on the first 100 C-units. Correlations between language and temperament were compared between girls and boys using the Fisher r-to-z transformation to examine the significance of potential moderating effects. OUTCOMES & RESULTS: Children's reported variability in Effortful Control did not correlate significantly with any of the child language measures. In contrast, children's Negative Affectivity and Surgency tended to demonstrate positive, albeit modest, correlations with those conversational language measures that were derived from the sample as a whole, rather than from a standardized number of utterances. MLU, as well as measures of NDW and NTW derived from standardized sample lengths of 100 C-units, did not correlate with any measure of child temperament. TNC demonstrated an unexpected negative correlation with child Surgency when it was derived from a standardized number of C-units, but not when derived from the entire sample length. Child biological sex did not moderate the significant associations between language and temperament measures. CONCLUSIONS & IMPLICATIONS: Overall, measures that control for volubility did not correlate significantly with child temperament; however, measures that reflected volubility tended to correlate weakly with some aspects of temperament, particularly Surgency. Results provide a degree of discriminant evidence for the validity of MLU and measures of type (i.e., NDW) and token use (i.e., NTW) when derived from a standardized number of utterances.

Conversational language use as a predictor of early reading development: language history as a moderating variable.

PURPOSE: The present study examined the nature of concurrent and predictive associations between conversational language use and reading development during early school-age years. METHOD: Language and reading data from 380 twins in the Western Reserve Reading Project were examined via phenotypic correlations and multilevel modeling on exploratory latent factors. RESULTS: In the concurrent prediction of children's early reading abilities, a significant interaction emerged between children's conversational language abilities and their history of reported language difficulties. Specifically, conversational language concurrently predicted reading development above and beyond variance accounted for by formal vocabulary scores, but only in children with a history of reported language difficulties. A similar trend was noted in predicting reading skills 1 year later, but the interaction was not statistically significant. CONCLUSIONS: Findings suggest a more nuanced view of the association between spoken language and early reading than is commonly proposed. One possibility is that children with and without a history of reported language difficulties rely on different skills, or the same skills to differing degrees, when completing early reading-related tasks. Future studies should examine the causal link between conversational language and early reading specifically in children with a history of reported language difficulties.

Use of the Twin Design to Examine Evocative Gene-Environment Effects within a Conversational Context.

The purpose of this study was to highlight the role of twin designs in understanding children's conversational interactions. Specifically, we (a) attempted to replicate the findings of genetic effects on children's conversational language use reported in DeThorne et al. (2008), and (b) examined whether the language used by examiners in their conversation with twins reflected differences in the children's genetic similarity. Behavioral genetic analyses included intraclass correlations and model fitting procedures applied to 514 same-sex twins (202 MZ, 294 DZ, 10 unknown zygosity) from the Western Reserve Reading Project (Petrill, Deater-Deckard, Thompson, DeThorne, & Schatschneider, 2006). Analyses focused on child and examiner measures of talkativeness, average utterance length, vocabulary diversity, and grammatical complexity from a fifteen-minute conversational exchange. Substantial genetic effects on children's conversational language measures replicated results from DeThorne et al. (2008) using an expanded sample. However, no familiality was reflected in the examiner language measures. Modest phenotypic correlations between child and examiner language measures suggested that differences in examiner language use may elicit differences in child language use, but evidence of evocative rGE in which genetic differences across children evoke differences in examiner language use, was not found. The discussion focuses on a comparison of findings to previous studies and implications for future research.

Children's history of speech-language difficulties: genetic influences and associations with reading-related measures.

PURPOSE: This study examined (a) the extent of genetic and environmental influences on children's articulation and language difficulties and (b) the phenotypic associations between such difficulties and direct assessments of reading-related skills during early school-age years. METHOD: Behavioral genetic analyses focused on parent-report data regarding the speech-language skills of 248 twin pairs (M = 6.08 years) from the Western Reserve Reading Project. In addition, phenotypic associations between children's speech-language status and direct assessments of early reading-related abilities were examined through hierarchical linear modeling (HLM). RESULTS: Probandwise concordance rates and intraclass tetrachoric correlations indicated high heritability for children's difficulties in expressive language and articulation, with estimates of .54 and .97 accordingly. HLM results indicated that children with histories of speech-language difficulties scored significantly lower than unaffected children on various measures of early reading-related abilities. CONCLUSIONS: Results from the parent-report survey provided converging evidence of genetic effects on children's speech and language difficulties and suggest that children with a history of speech-language difficulties are at risk for lower performance on early reading-related measures. The extent of risk differed across measures and appeared greatest for children who demonstrated a history of difficulties across articulation, expressive language, and receptive language. Implications for future genetic research and clinical practice are discussed.

Listeners' Perceptions of Language Use in Children.

Past research suggests that when children's communication skills do not match others' expectations, children are likely to be perceived negatively and may consequently experience less academic and social success. This project focused on listeners' perceptions of three children, one with specific language impairment (SLI) and two typically developing peers. The listeners consisted of teachers, speech-language pathologists, undergraduate students, and sixth-grade students. All four listener groups consistently perceived the child with SLI more negatively than the typically developing youngsters, thereby illuminating the need for clinicians to (a) increase their awareness of personal biases, (b) educate parents and teachers regarding the nature of SLI,