Talking to Children Matters

TLDR

Infants differ substantially in their rates of language growth, and slow growth predicts later academic difficulties. The study examined how the quantity of child‑directed speech in low‑socioeconomic Spanish‑speaking families affects infants’ real‑time language‑processing skills and vocabulary growth. The authors recorded all‑day parent‑infant interactions at home to quantify variability in caregiver child‑directed speech. Infants exposed to more child‑directed speech processed familiar words faster and had larger expressive vocabularies at 24 months, and mediation analysis indicated that enhanced language‑processing efficiency mediated the relationship between child‑directed speech and vocabulary growth.

Abstract

Infants differ substantially in their rates of language growth, and slow growth predicts later academic difficulties. In this study, we explored how the amount of speech directed to infants in Spanish-speaking families low in socioeconomic status influenced the development of children’s skill in real-time language processing and vocabulary learning. All-day recordings of parent-infant interactions at home revealed striking variability among families in how much speech caregivers addressed to their child. Infants who experienced more child-directed speech became more efficient in processing familiar words in real time and had larger expressive vocabularies by the age of 24 months, although speech simply overheard by the child was unrelated to vocabulary outcomes. Mediation analyses showed that the effect of child-directed speech on expressive vocabulary was explained by infants’ language-processing efficiency, which suggests that richer language experience strengthens processing skills that facilitate language growth.