The Influence of Child-Produced Speech on Infant Language Development

Project Summary Early language skills have been linked to experience with language in the real world. However, the majority of this research has focused on infant’s experiences with adult caregivers. The majority of children, however, hear language from other children, in addition to adult caregivers, whether that be in the home, on the playground, or in childcare settings, to name a few. In fact, 80% of US children have at least one sibling (Census data, 2010), and out pilot data suggests that infants with siblings hear speech from children every 49s. However, having an older sibling seems to have a negative effect on language development, with younger siblings showing slower language development than first-born children. The proposed work investigates how speech from young children may influence language development, in an effort to understand why language development differs for later- relative to first-born children. Its overall objective is to establish how infants process speech from children relative to adults, whether speech from children differs systematically in content and complexity, and how processing of child-produced speech and the content of child-produced speech influence language development. Aim 1 tests two central facets of speech perception: preferences for speech produced by children vs. adults, and word recognition for speech produced by children vs. adults. Aim 2 collects and fully transcribes a corpus of play sessions between a parent, sibling, and young infant, to understand what older siblings say in the presence of younger infants, and how that differs from the input their receive from adult caregivers. Aim 3 asks whether infant’s preference for or processing of child-produced speech from Aim 1 relates to their vocabulary growth at 18 months, and whether infant’s own experiences with child-produced speech during play sessions from Aim 2 also shapes vocabulary growth at 18 months. Results from this set of Aims will provide important information about the role of child-produced speech in early language development. Understanding whether speech from young children is preferentially attended to by infants, and whether it provides different content for infants to learn from will inform how we can differentially support language development for infants who may have different experiences with child-produced speech, which is likely to vary across cultures, linguistic backgrounds, and socioeconomic status.