Expressive Language Development in Twins versus Singletons at Early School Age By

The current study investigated whether twins and singletons differed in their expressive language development at school age. Comparisons focused on language samples and formalized vocabulary assessments gathered from 28 twins and 28 singletons within the Western Reserve Reading Project; the two groups were matched on age, gender, and parent education level. The children’s language samples, taken from conversational interactions, were analyzed for mean length of utterance, number of different words, number of total words, and total number of conjunctions, all of which were converted to z-scores and averaged to form a Conversational Composite. Similarly, children’s scores on the Stanford Binet Vocabulary subtest (Thorndike, Hagen, & Sattler, 1986) and the Boston Naming Test (Goodglass & Kaplan, 2001) were converted into a Formal Language Composite. Mean comparisons via t-test revealed no group differences between twins and on either of the composites. In addition to the Conversational and Formal Composites, a pilot coding process for topic initiation and management was completed for 3 twin-sibling pairs, or a total of 6 children. The topics of modeling clay, school, and hobbies emerged as the most common across transcripts. Measures related to topic management revealed consistent overlap between the two groups. Examiners, in comparison to children, initiated twice as many topic shifts. In sum, results suggest that twinship in and of itself does not indicate a substantial risk for school-age expressive language difficulties, and provide early descriptive data to analyze the transactional nature of topic management within conversational interactions.