Linguistic environment of 1- to 2-year-old twins.

The current study investigated differences in the language learning environments of singletons and twins, with special reference to pragmatic factors that might be expected to differ in dyadic and triadic interactive situations. Six twin pairs and 12 singleton children (all firstborn) were observed in natural interactions with their mothers, once at 15 months of age and again at 21 months of age. Twins were lower than singletons on all measures of language development. The language learning environments of the two groups differed as well. Although twin mothers spoke and interacted with their children as much as singleton mothers when twins were analyzed together, when analyzed from the point of view of the individual twin child, twin children received less speech directed specifically to them, participated in fewer and shorter episodes of joint attentional focus, and had fewer and shorter conversations with their mothers. In addition, twin mothers were more directive in their interactional styles. Correlational analyses indicated that variation of these language learning environment factors for the sample as a whole, as well as variation for some of these factors within the twin group itself, was related to early language growth. It is proposed that both the quantitative and qualitative differences observed in the language learning environments of singletons and twins derive from the nature of the triadic situation and that these differences have important effects on the child's early language development.