Effect of maternal depression on infant-directed speech to prelinguistic infants: Implications for language development.

Christa Lam-Cassettari,Jane Kohlhoff,Claudia Männel

doi:10.1371/journal.pone.0236787

Christa Lam-Cassettari, Jane Kohlhoff + Show 1 more

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https://doi.org/10.1371/journal.pone.0236787

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Abstract

The nature and timing of caregivers’ speech provides an important foundation for infant attention and language development in the first year of life. Infant-directed speech is a key component of responsive parent-infant communication that is typically characterised by exaggerated intonation and positive affect. This study examines the effect of postnatal depression on the expression of positive vocal affect and pitch, the quantity of mothers’ infant-directed speech input and the timing of vocal responses between mother and infant. Postnatal mothers currently experiencing symptoms of depression (n = 13) were matched to postnatal mothers who were not experiencing symptoms of depression (n = 13), and audio-recorded while playing with their 6-month-old infants. Compared with depressed mothers, non-depressed mothers used a higher mean pitch and pitch range, spoke more, gave faster verbal responses and were rated as expressing more positive valence in their voice. These preliminary findings indicate that mothers experiencing low mood use less infant-directed speech and less exaggerated pitch with prelinguistic infants. Postnatal depression is a major health issue that adversely impacts the parent and child. Early interventions for PND may benefit from identifying ways to support the timing of conversations and mothers’ use of appropriate vocal pitch and infant-directed speech modifications. Further research is needed to confirm whether these strategies support early conversations.

Highlights

Before infants utter their first words, they are learning the protocols of social interaction through the daily experiences they have with their caregivers [1]
The Infant-directed speech (IDS) of mothers in the non-Postnatal depression (PND) group was perceived to have a larger degree of positive emotional valence (t = 4.067, df = 22, p = 0.001) 95% CI [5.62, 8.31] and greater level of arousal (t = 3.785, df = 22, p = 0.001) 95% CI [5.62, 8.31]. This preliminary study tested whether measures of vocal pitch (F0), affective intent, number of maternal vocalisations, number of infant vocalisations, and maternal response latency following infant vocalisations differ in IDS of mothers with elevated symptoms of PND and a matched sample without PND
Mothers with elevated PND symptoms spoke with a lower F0 and less F0 variation, two features that are exaggerated in prototypical IDS [3,4], and known to engage and maintain infant attention to speech [4,7]

Summary

Introduction

Before infants utter their first words, they are learning the protocols of social interaction through the daily experiences they have with their caregivers [1]. Gaining better understanding the effects of PND on IDS pitch, vocal affect and motherinfant vocal turn-taking behaviours will provide new insight into components of the early social environment that would benefit from increased support to mitigate the effects of PND before infants develop poor outcomes. To this end, the current study compared acoustic, perceptual, temporal and quantitative measures of IDS (pitch, ratings of vocal affect, number of words, and vocal response timing), and the quantity of infant vocalisations in infants aged around 6-months. Since maternal speech input has been shown to influence infant babble [15,16,39], we hypothesised that the frequency of infant vocalisations would emerge later due to less exposure to IDS

Materials and methods

Participants

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