Infants’ intentionally communicative vocalizations elicit responses from caregivers and are the best predictors of the transition to language: A longitudinal investigation of infants’ vocalizations, gestures and word production

Abstract

What aspects of infants’ prelinguistic communication are most valuable for learning to speak, and why? We test whether early vocalizations and gestures drive the transition to word use because, in addition to indicating motoric readiness, they (a) are early instances of intentional communication and (b) elicit verbal responses from caregivers. In study 1, 11 month olds (N = 134) were observed to coordinate vocalizations and gestures with gaze to their caregiver's face at above chance rates, indicating that they are plausibly intentionally communicative. Study 2 tested whether those infant communicative acts that were gaze‐coordinated best predicted later expressive vocabulary. We report a novel procedure for predicting vocabulary via multi‐model inference over a comprehensive set of infant behaviours produced at 11 and 12 months (n = 58). This makes it possible to establish the relative predictive value of different behaviours that are hierarchically organized by level of granularity. Gaze‐coordinated vocalizations were the most valuable predictors of expressive vocabulary size up to 24 months. Study 3 established that caregivers were more likely to respond to gaze‐coordinated behaviours. Moreover, the dyadic combination of infant gaze‐coordinated vocalization and caregiver response was by far the best predictor of later vocabulary size. We conclude that practice with prelinguistic intentional communication facilitates the leap to symbol use. Learning is optimized when caregivers respond to intentional vocalizations with appropriate language.

Early Pragmatics in Deaf and Hard of Hearing Infants

“…In recent research with typically developing, typically hearing infants, researchers have identified specific early communicative behaviors as being theoretically important indicators of readiness for language learning and good empirical predictors of later language development. 2,[23][24][25][26][27] Positive predictors include the frequency with which infants produce give gestures, show gestures, index-finger pointing, and communicative vocalizations (operationalized as vocalizations made within 1 second of looking to the caregiver's face). Alongside first words, these behaviors are thought to be positive predictors because they indicate social-cognitive readiness for language development, and because they elicit timely and informative caregiver responses, which are known to scaffold further development.…”

“…Indeed, the frequency with which infants rely on some other gestures (eg, openhand pointing) is a negative predictor of language development. 25,27 Thus, when assessing early pragmatic development in DHH infants, it has become apparent that investigating precise frequencies of specific infant naturalistic behaviors is important.…”

“…It is the latter that is known to predict outcomes. 27 Moreover, although DHH infants' vocalizations have been explored in terms of their phonology (with evidence of delay 38,39 ), there has been little study of the communicative use of vocalizations (regardless of phonological properties). It has recently been found that one of the most valuable predictors of typically hearing infants' transition to speech is the frequency with which they produce communicative vocalizations that are then responded to by the caregiver with language that is relevant to the infant's focus of attention.…”

“…An infant who benefits from such interactions with a frequency 1 SD above the mean at 12 months is predicted to produce ∼28 more words than the average infant by 19 months. 27…”

“…Following the coding scheme reported in Donnellan et al, 27 video recordings were coded for infant gestures, vocalizations, gaze to caregiver's face, and recognizable British Sign Language (BSL) signs by using EUDICO Linguistic Annotator software (ELAN) 41 by the first author. Gestures were categorized as either give, show, or index-finger point.…”