Quality of early parent input predicts child vocabulary 3 years later

Abstract

Children vary greatly in the number of words they know when they enter school, a major factor influencing subsequent school and workplace success. This variability is partially explained by the differential quantity of parental speech to preschoolers. However, the contexts in which young learners hear new words are also likely to vary in referential transparency; that is, in how clearly word meaning can be inferred from the immediate extralinguistic context, an aspect of input quality. To examine this aspect, we asked 218 adult participants to guess 50 parents' words from (muted) videos of their interactions with their 14- to 18-mo-old children. We found systematic differences in how easily individual parents' words could be identified purely from this socio-visual context. Differences in this kind of input quality correlated with the size of the children's vocabulary 3 y later, even after controlling for differences in input quantity. Although input quantity differed as a function of socioeconomic status, input quality (as here measured) did not, suggesting that the quality of nonverbal cues to word meaning that parents offer to their children is an individual matter, widely distributed across the population of parents.

Keywords: SES; language acquisition; word learning.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.

Effect of quality of early input at 14–18 mo on child comprehension vocabulary at 54 mo. (A) Quality of word learning instances (average HSP accuracy per family) at 14–18 mo predicts child comprehension vocabulary (PPVT) at 54 mo. (B) This effect holds even after controlling for the quantity of early input (average parent words per minute at 14 and 18 mo). Each point represents a single family (n = 50).

Fig. 2.

Effect of SES on quantity and quality of parent input at 14–18 mo. (A) SES of family predicts average words per minute uttered by the child’s parent during two 90-min recording sessions at 14 and 18 mo. (B) SES of family does not predict quality of parent input at 14 and 18 mo (accuracy measure calculated from HSP). Each point represents a single family (n = 50).

Fig. 3.

Effect of quality of parent input for unknown words on child comprehension vocabulary at 54 mo. (A) Quality of unknown word learning instances (average HSP accuracy of vignettes in which child does not know the target word) at 14–18 mo predicts child comprehension vocabulary (PPVT) at 54 mo. (B) This effect holds even after controlling for the quantity of early input (average parent words per minute at 14 and 18 mo). Each point represents a single family (n = 42).