Genetic effects on children's conversational language use

The effects of maternal input on language in the absence of genetic confounds: Vocabulary development in internationally adopted children

Previous studies have found correlations between parent input and child language outcomes, providing prima facie evidence for a causal relation. However, this could also reflect the effects of shared genes. The present study removed this genetic confound by measuring English vocabulary growth in 29 preschool-aged children (21 girls) aged 31-73 months and 17 infants (all girls) aged 15-32 months adopted from China and Eastern Europe and comparing it to speech produced by their adoptive mothers. Vocabulary growth in both groups was correlated with maternal input features; in infants with mean-length of maternal utterance, and in preschoolers with both mean-length of utterance and lexical diversity. Thus, input effects on language outcomes persist even in the absence of genetic confounds.

Children Born Prematurely May Demonstrate Catch-Up Growth in Pre-Adolescence

Introduction Children born prematurely often score lower on standardized tests of language in early childhood. Less is known about longer term outcomes. This investigation considered language outcomes in pre-adolescent children born very preterm/very low birthweight, as assessed by both standardized test scores and language sample measures, and explored attention abilities as a possible moderating factor. Method The present investigation provided a longitudinal follow-up to Mahurin Smith et al. (2014) by examining the language outcomes of 84 children at the 11-year time point (39 with a history of prematurity and 45 born at full term) and a total of 82 at the 12-year time point (37 with a history of prematurity, 45 born at full term). Assessments included subtests of the Clinical Evaluation of Language Fundamentals- Fourth Edition, productive language measures taken from narrative tasks, and parent and examiner ratings of attention. Results Gestational age significantly predicted standardized language scores at age 11 years, but this effect was no longer statistically significant at age 12 years. When parent ratings of attention were considered as additional variables, gestational age was no longer a significant predictor. Gestational age did not serve as a significant predictor for the productive language measures at either time point. Discussion Results indicate that catch-up growth in language may take place in pre-adolescence for many children born prematurely. Clinical implications focus on the need to utilize multiple forms of language assessment and to directly consider the potential role of attention on standard test results.

Rare Vocabulary Production in School-Age Narrators From Low-Income Communities

Purpose This study was designed to assess the utility of a tool for automated analysis of rare vocabulary use in the spoken narratives of a group of school-age children from low-income communities. Method We evaluated personal and fictional narratives from 76 school-age children from low-income communities (M _age = 9;3 [years;months]). We analyzed children's use of rare vocabulary in their narratives, with the goal of evaluating relationships among rare vocabulary use, performance on standardized language tests, language sample measures, sex, and use of African American English. Results Use of rare vocabulary in school-age children is robustly correlated with established language sample measures. Male sex was also significantly associated with more frequent rare vocabulary use. There was no association between rare vocabulary use and use of African American English. Discussion Evaluation of rare vocabulary use in school-age children may be a culturally fair assessment strategy that aligns well with existing language sample measures.

Language Development and Impairment in Children With Mild to Moderate Sensorineural Hearing Loss

PURPOSE

The goal of this study was to examine language development and factors related to language impairments in children with mild to moderate sensorineural hearing loss (MMHL).

METHOD

Ninety children, aged 8-16 years (46 children with MMHL; 44 aged-matched controls), were administered a battery of standardized language assessments, including measures of phonological processing, receptive and expressive vocabulary and grammar, word and nonword reading, and parental report of communication skills. Group differences were examined after controlling for nonverbal ability.

RESULTS

Children with MMHL performed as well as controls on receptive vocabulary and word and nonword reading. They also performed within normal limits, albeit significantly worse than controls, on expressive vocabulary, and on receptive and expressive grammar, and worse than both controls and standardized norms on phonological processing and parental report of communication skills. However, there was considerable variation in performance, with 26% showing evidence of clinically significant oral or written language impairments. Poor performance was not linked to severity of hearing loss nor age of diagnosis. Rather, outcomes were related to nonverbal ability, maternal education, and presence/absence of family history of language problems.

CONCLUSIONS

Clinically significant language impairments are not an inevitable consequence of MMHL. Risk factors appear to include lower maternal education and family history of language problems, whereas nonverbal ability may constitute a protective factor.

Language Outcomes in Young Children with Mild to Severe Hearing Loss

OBJECTIVES

This study examined the language outcomes of children with mild to severe hearing loss during the preschool years. The longitudinal design was leveraged to test whether language growth trajectories were associated with degree of hearing loss and whether aided hearing influenced language growth in a systematic manner. The study also explored the influence of the timing of hearing aid fitting and extent of use on children's language growth. Finally, the study tested the hypothesis that morphosyntax may be at particular risk due to the demands it places on the processing of fine details in the linguistic input.

DESIGN

The full cohort of children in this study comprised 290 children who were hard of hearing (CHH) and 112 children with normal hearing who participated in the Outcomes of Children with Hearing Loss (OCHL) study between the ages of 2 and 6 years. CHH had a mean better-ear pure-tone average of 47.66 dB HL (SD = 13.35). All children received a comprehensive battery of language measures at annual intervals, including standardized tests, parent-report measures, and spontaneous and elicited language samples. Principal components analysis supported the use of a single composite language score for each of the age levels (2, 3, 4, 5, and 6 years). Measures of unaided (better-ear pure-tone average, speech intelligibility index) and aided (residualized speech intelligibility index) hearing were collected, along with parent-report measures of daily hearing aid use time. Mixed modeling procedures were applied to examine the rate of change (227 CHH; 94 children with normal hearing) in language ability over time in relation to (1) degree of hearing loss, (2) aided hearing, (3) age of hearing aid fit and duration of use, and (4) daily hearing aid use. Principal components analysis was also employed to examine factor loadings from spontaneous language samples and to test their correspondence with standardized measures. Multiple regression analysis was used to test for differential effects of hearing loss on morphosyntax and lexical development.

RESULTS

Children with mild to severe hearing loss, on average, showed depressed language levels compared with peers with normal hearing who were matched on age and socioeconomic status. The degree to which CHH fell behind increased with greater severity of hearing loss. The amount of improved audibility with hearing aids was associated with differential rates of language growth; better audibility was associated with faster rates of language growth in the preschool years. Children fit early with hearing aids had better early language achievement than children fit later. However, children who were fit after 18 months of age improved in their language abilities as a function of the duration of hearing aid use. These results suggest that the language learning system remains open to experience provided by improved access to linguistic input. Performance in the domain of morphosyntax was found to be more delayed in CHH than their semantic abilities.

CONCLUSION

The data obtained in this study largely support the predictions, suggesting that mild to severe hearing loss places children at risk for delays in language development. Risks are moderated by the provision of early and consistent access to well-fit hearing aids that provide optimized audibility.

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.

Genetic and Environmental Links Between Natural Language Use and Cognitive Ability in Toddlers

Although the phenotypic correlation between language and nonverbal cognitive ability is well-documented, studies examining the etiology of the covariance between these abilities are scant, particularly in very young children. The goal of this study was to address this gap in the literature by examining the genetic and environmental links between language use, assessed through conversational language samples, and nonverbal cognition in a sample of 3-year-old twins (N = 281 pairs). Significant genetic and nonshared environmental influences were found for nonverbal cognitive ability and language measures, including mean length of utterance and number of different words, as well as significant genetic covariance between cognitive ability and both language measures.

Causal effects on child language development: A review of studies in communication sciences and disorders

We reviewed recent studies published across key journals within the field of communication sciences and disorders (CSD) to survey what causal influences on child language development were being considered. Specifically, we reviewed a total of 2921 abstracts published within the following journals between 2003 and 2013: Language, Speech, and Hearing Services in Schools (LSHSS); American Journal of Speech-Language Pathology (AJSLP); Journal of Speech, Language, and Hearing Research (JSLHR); Journal of Communication Disorders (JCD); and the International Journal of Language and Communication Disorders (IJLCD). Of the 346 eligible articles that addressed causal factors on child language development across the five journals, 11% were categorized as Genetic (37/346), 83% (287/346) were categorized as Environmental, and 6% (22/346) were categorized as Mixed. The bulk of studies addressing environmental influences focused on therapist intervention (154/296=52%), family/caregiver linguistic input (65/296=22%), or family/caregiver qualities (39/296=13%). A more in-depth review of all eligible studies published in 2013 (n=34) revealed that family/caregiver qualities served as the most commonly controlled environmental factor (e.g., SES) and only 3 studies explicitly noted the possibility of gene-environment interplay. This review highlighted the need to expand the research base for the field of CSD to include a broader range of environmental influences on child language development (e.g., diet, toxin exposure, stress) and to consider more directly the complex and dynamic interplay between genetic and environmental effects.

LEARNING OUTCOMES

Readers will be able to highlight causal factors on child language development that have been studied over the past decade in CSD and recognize additional influences worthy of consideration. In addition, readers will become familiar with basic tenets of developmental systems theory, including the complex interplay between genetic and environmental factors that shapes child development.

From aardvark to ziggurat: A new tool for assessing children's use of rare vocabulary

This study introduces a resource for examining children's use of low-frequency vocabulary and describes preliminary evidence of its validity. Using a corpus of >1400 transcripts from school-aged children, we derived a concordance of all words spoken by the children and generated a list of 2079 uncommon words we have called WERVE, the Wordlist for Expressive Rare Vocabulary Evaluation. Preliminary validity evidence for WERVE was examined through correlation analyses with WERVE results and other common language measures in a test sample of 112 children age 7 and 8 years. In addition, we replicated the correlation analyses using a sample of 38 eight-year-old children. WERVE results correlated strongly with established language sample measures and to a lesser but frequently significant degree with standardized test results. Results also showed developmental change from age 7 to age 8. Correlations ranged from medium to large. These results suggest that WERVE may be a useful tool for language sample researchers to explore.

Distinguishing between casual talk and academic talk beginning in the preschool years: an important consideration for speech-language pathologists

PURPOSE

The need for speech-language pathologists (SLPs) to consider an academic talk (AT) register in addition to an everyday casual talk (CT) register of oral language with children beginning in the preschool years is presented, the AT and CT registers are distinguished in a comprehensive manner, ideas regarding AT language assessment are proposed, and suggestions for fostering children's skills with the AT register are offered.

METHOD

Extant research and scholarship from a wide variety of disciplines are integrated and organized.

RESULTS

The author discusses the role of the SLP in supporting AT skills beginning in the preschool years and the added risk of difficulties with the AT register for children with language impairment who are from diverse backgrounds. Two broad categories-social-interactive and cognitive-that give rise to linguistic features that differentiate between the CT and AT registers are deduced from extant scholarship.

CONCLUSIONS

SLPs should consider children's competence with the AT register as they work to prepare preschoolers and older children for the language demands of school.

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.

There Is a World Outside of Experimental Designs: Using Twins to Investigate Causation

This study introduces a co-twin control method commonly used in the medical literature but not often within educational research. This method allows for a comparison of twins discordant for an "exposure," approximating alternative outcomes in the counterfactual model. Example analyses use data drawn from the Florida Twin Project on Reading to determine whether exposure to "teacher quality," measured by growth in oral reading fluency (ORF) scores of classmates, causally affects ORF performance of twins in the subsequent years. The analysis highlights PROC MIXED in SAS, including a novel expansion to allow for the nested data. Results from 2,788 twins suggested that being in classrooms with lower teacher quality in first grade leads to lower ORF scores in second and third grade with little indication of possible genetic or environmental confounding.

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.

The etiology of diverse receptive language skills at 12 years

PURPOSE

In the 2nd decade of life, language skills expand in both quantitative and qualitative ways. The etiology of these new skills and the relationships among them have been little explored.

METHOD

Taking advantage of widespread access to inexpensive and fast Internet connections in the United Kingdom, we administered four Web-based measures of receptive language development--Vocabulary, Listening Grammar, Figurative Language, and Making Inferences--to a sample of 12-year-old twin pairs (N=4,892) participating in the Twins Early Development Study (TEDS; Oliver & Plomin, 2007).

RESULTS

The 4 measures showed moderate phenotypic intercorrelation. All 4 showed moderate genetic influence (a2 between .25 and .36) and low shared environmental influence (c2 between .13 and .19). The median genetic correlation among the 4 measures was .87, indicating strong genetic overlap among them. A latent factor score for Language, based on the common variance among the measures, showed substantial genetic influence (a2=.59) and moderate shared environmental influence (c2=.28). A small but significant sex difference favored females on the Listening Grammar and Making Inferences tests, but there was no evidence for sex differences in the etiology of any of the measures.

CONCLUSION

Despite the emergence of new skills at this developmental period, from the etiological perspective, language skills remain relatively undifferentiated at an etiological level.

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.

Genetic influences on language, reading, and mathematics skills in a national sample: an analysis using the National Longitudinal Survey of Youth

PURPOSE

The present study had two purposes: provide an illustration of use of the National Longitudinal Survey of Youth 1979 Children's (CNLSY; U.S. Department of Labor, 2009) database and use the database to seek convergent evidence regarding the magnitude and significance of genetic effects influencing low and typical performers on measures of language, reading, and mathematics.

METHODS

A kinship algorithm that assigned a degree of genetic relatedness to all available pairings was applied to the 1994 wave of the CNLSY sample. Four cognitive achievement outcomes related to language, reading, and mathematics were analyzed across the general sample as well as for children selected below the lowest 20(th) percentile.

RESULTS

The tests of receptive vocabulary, decoding, reading comprehension, and mathematics all suggested estimates of group heritability and full sample heritability of moderate effect sizes, and all estimates were statistically significant. Furthermore, all estimates were within confidence intervals of previously reported estimates from twin and adoption studies.

CONCLUSION

The present study provides additional support for significant genetic effects across low and wide ranges of specific achievement. Moreover, this study supports that genetic influences on reading, language, and mathematics are generalizable beyond twin and adoption studies.

Environmental influences on the longitudinal covariance of expressive vocabulary: measuring the home literacy environment in a genetically sensitive design

BACKGROUND

Despite the well-replicated relationship between the home literacy environment and expressive vocabulary, few studies have examined the extent to which the home literacy environment is associated with the development of early vocabulary ability in the context of genetic influences. This study examined the influence of the home literacy environment on the longitudinal covariance of expressive vocabulary within a genetically sensitive design.

METHODS

Participants were drawn from the Western Reserve Reading Project, a longitudinal twin project of 314 twin pairs based in Ohio. Twins were assessed via three annual home visits during early elementary school; expressive vocabulary was measured via the Boston Naming Test (BNT), and the Home Literacy Environment (HLE) was assessed using mothers' report.

RESULTS

The heritability of the BNT was moderate and significant at each measurement occasion, h(2) = .29-.49, as were the estimates of the shared environment, c(2) = .27-.39. HLE accounted for between 6-10% of the total variance in each year of vocabulary assessment. Furthermore, 7-9% of the total variance of the stability over time in BNT was accounted for by covariance in the home literacy environment.

CONCLUSIONS

These results indicate that aspects of the home literacy environment, as reported by mothers, account for some of the shared environmental variance associated with expressive vocabulary in school aged children.

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.