Pre-linguistic infants employ complex communicative loops to engage mothers in social exchanges and repair interaction ruptures.

Nadège Bourvis,Ruth Feldman,Magi Singer,Nicolas Bodeau,David Cohen,Mohamed Chetouani,Catherine Saint Georges

doi:10.1098/rsos.170274

Abstract

Language has long been identified as a powerful communicative tool among humans. Yet, pre-linguistic communication, which is common in many species, is also used by human infants prior to the acquisition of language. The potential communicational value of pre-linguistic vocal interactions between human infants and mothers has been studied in the past decades. With 120 dyads (mothers and three- or six-month-old infants), we used the classical Still Face Paradigm (SFP) in which mothers interact freely with their infants, then refrain from communication (Still Face, SF), and finally resume play. We employed innovative automated techniques to measure infant and maternal vocalization and pause, and dyadic parameters (infant response to mother, joint silence and overlap) and the emotional component of Infant Directed Speech (e-IDS) throughout the interaction. We showed that: (i) during the initial free play mothers use longer vocalizations and more e-IDS when they interact with older infants and (ii) infant boys exhibit longer vocalizations and shorter pauses than girls. (iii) During the SF and reunion phases, infants show marked and sustained changes in vocalizations but their mothers do not and (iv) mother–infant dyadic parameters increase in the reunion phase. Our quantitative results show that infants, from the age of three months, actively participate to restore the interactive loop after communicative ruptures long before vocalizations show clear linguistic meaning. Thus, auditory signals provide from early in life a channel by which infants co-create interactions, enhancing the mother–infant bond.

Highlights

It is widely accepted that language acquisition is one of the most significant achievements of Homo sapiens [1] and allows complex communication skills to develop
We developed an experimental setting in which we used: (i) the Still Face Paradigm; (ii) two infant age groups: three- and six-month-old infants; (iii) three SF conditions to provide a gradient of stress; (iv) computational analysis of audio mother–infant interaction including automatic measures of both low level features [32] and high level features, namely mothers’ emotional speech (e-infant-directed speech (IDS)) [22,33]
The linear mixed models (LMM) applied to each variable showed that the infants’ age had an effect on mother parameters only, where mothers showed longer vocalizations (β = 0.077, p = 0.022) and used more emotional component of IDS (e-IDS) with the six-month-old infants

Summary

Introduction

It is widely accepted that language acquisition is one of the most significant achievements of Homo sapiens [1] and allows complex communication skills to develop. While language is not present at birth in human infants and does not develop in other animals, communication and social interactions are widely observed throughout the animal kingdom and occur well before the acquisition of formal language. These early communicative exchanges carry an important survival function, bind the young to the larger social group, and have an imprinting function on the infant’s brain during sensitive periods for brain maturation [2,3]. Pheromones that are present in the nipple, promotes infant bonding [8] Such multimodal sensory input contributes to infant cognitive and social-emotional development [2]

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Conclusion