Purpose-The present study examined the extent of genetic and environmental influences on individual differences in children's conversational language use.Method-Behavioral genetic analyses focused on conversational measures and 2 standardized tests from 380 twins (M = 7.13 years) during the 2nd year of the Western Reserve Reading Project (S. A. Petrill, K. Deater-Deckard, L. A. Thompson, L. S. DeThorne, & C. . Multivariate analyses using latent factors were conducted to examine the extent of genetic overlap and specificity between conversational and formalized language.Results-Multivariate analyses revealed a heritability of .70 for the conversational language factor and .45 for the formal language factor, with a significant genetic correlation of .37 between the two factors. Specific genetic effects were also significant for the conversational factor.Conclusions-The current study indicated that over half of the variance in children's conversational language skills can be accounted for by genetic effects with no evidence of significant shared environmental influence. This finding casts an alternative lens on past studies that have attributed differences in children's spontaneous language use to differences in environmental language exposure. In addition, multivariate results generally support the context-dependent construction of language knowledge, as suggested by the theory of activity and situated cognition (J. S. Brown, A. Collins, & P. Duguid, 1989; T. A. Ukrainetz, 1998), but also indicate some degree of overlap between language use in conversational and formalized assessment contexts. Keywordsexpressive language assessment; elementary school pupils; language Contact author: Laura S. DeThorne, University of Illinois at Urbana-Champaign, 901 South Sixth Street, Champaign, IL 61820. E-mail: lauras@uiuc.edu. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptA number of twin studies have used quantitative genetic methods to estimate environmental and genetic influences on language development. The twin design hinges on a comparison of monozygotic (MZ) and dizygotic (DZ) twins. Because MZ twins share 100% of their segregating genes and DZ twins share on average 50%, higher similarity between MZ twins is indicative of genetic effects (Plomin, DeFries, McClearn, & McGuffin, 2001). One means of measuring twin similarity is by comparing intraclass correlations for MZ versus DZ twins. The larger the MZ intraclass correlation in comparison with the DZs, the higher heritability (h 2 ) will be. In contrast, shared environmental effects (c 2 ) lead to similarity across all twins. Consequently, similar intraclass correlations between MZ and DZ twins are indicative of shared environmental effects. Finally, the extent to which MZ twins appear dissimilar is attributed to a combination of nonshared environment and error (e 2 ). Nonshared environmental influences are unique to the individual.An underlying assumption of twin methodology is that the nature of genetic and environ...

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This study compared school-age outcomes for 57 children born prematurely, at ≤32 weeks or <1500g, with outcomes for 57 children born at full term with no reported perinatal complications. The two groups were matched for age, sex, race, and parental education. Data came from the Western Reserve Reading Project and included discourse-level language samples collected at three points in time, each a year apart. In addition, standardized test results were obtained for IQ, digit span, and global language ability. The language samples were analyzed to yield a number of semantic and syntactic measures which were condensed via factor analysis to a semantic score and a syntactic score. Regression models showed statistically significant differences between the two groups for standardized test results, with more ambiguous results for the discourse-level language measures. The control group outperformed the premature group on both semantic and syntactic measures, but those differences never reached statistical significance and narrowed markedly at the third-year assessment point. These findings suggest that in the absence of frank neurological impairment, sophisticated semantic and syntactic skills may be relatively intact in the conversational and narrative language of children born prematurely. The decrements observed on standardized assessments of language and cognition may arise from deficits in domains such as attention or executive function, rather than reflecting significant impairment in their ability to learn language.

These findings suggest that speech motor control matures beyond young adulthood and that linguistic complexity in a repetitive task does not appear to have a consistent effect on measures of speech movement.

Most software for language analysis has relied on an interaction between the metalinguistic skills of a human coder and the calculating ability of the machine to produce reliable results. However, probabilistic parsing algorithms are now capable of highly accurate and completely automatic identification of grammatical word classes. The program Computerized Profiling combines a probabilistic parser with modules customized to produce four clinical grammatical analyses: MLU, LARSP, IPSyn, and DSS. The accuracy of these analyses was assessed on 69 language samples from typically developing, speech-impaired, and language-impaired children, 2 years 6 months to 7 years 10 months. Values obtained with human coding and by the software alone were compared. Results for all four analyses produced automatically were comparable to published data on the manual interrater reliability of these procedures. Clinical decisions based on cutoff scores and productivity data were little affected by the use of automatic rather than human-generated analyses. These findings bode well for future clinical and research use of automatic language analysis software.