When parents interact with young infants, they spontaneously use a special type of speech known as infant-directed speech, also known as babytalk or parentese. Compared to adult-directed speech, infant-directed speech has a number of characteristic acoustic and linguistic components, which have been proposed to serve specific functions in young infants’ emotional and linguistic development. This fellowship focused on identifying the components that specifically serve a linguistic function; that is, the properties of infant-directed speech that assist infants in the challenging task of learning their native language. In addition, this was the first project to investigate these properties in infant-directed speech produced by bilingual parents in interactions with bilingual infants. Unlike their monolingual peers, bilingual infants face the additional challenge of differentiating their two native languages and tracking the information belonging to each language separately, so it is possible that the linguistic adaptations of infant-directed speech may yield additional benefits for this infant population.
This project pursued two main objectives: (1) To identify the individual acoustic components of infant-directed speech in relation to infants’ age and language ability, and (2) To experimentally isolate these individual components of infant-directed speech and measure the extent to which each component facilitates language processing in the first year of life. For this purpose, a combination of detailed acoustic analyses and experimental behavioral and neurophysiological tasks were used with four- to nine-month-old infants who were acquiring Spanish and Basque in monolingual and bilingual contexts.
This research has several practical implications. First, it enriches our understanding about bilingual language development. The majority of infants around the world acquire more than one language from birth, yet most current knowledge about language development is based on monolingual evidence. The results of this research inform caregivers and educators that with rich language exposure, bilingual infants can achieve dual-language proficiency that is on par with the one-language proficiency of their monolingual peers. Second, these results demonstrate that parents have direct access to one of the most effective child development tools - their own infant-directed speech. Access to rich linguistic input allows infants to develop language abilities in a rapid and effortless manner in their first years of life. This fellowship concentrated on identifying the components of infant-directed speech critical to enhance language development and provide monolingual and bilingual infants with the optimal type of linguistic input to achieve their maximum potential in the development of early language abilities.
