Children vary greatly in the number of words they know when they enter school, and this is a major factor influencing their subsequent school and workplace success. A new study published in the Proceedings of the National Academy of Sciences has found that contextualised speech input from parents during the second year of children’s lives correlated with the size of their vocabularies three years later.
The researchers asked 218 adult participants to guess 50 parents’ words from muted videos of their interactions with their 14- to 18-month-old children. They found systematic differences in how easily individual parents’ words could be identified purely from this socio-visual context. For example, it is easier for children to acquire the meaning of “zebra” in the visual presence of a zebra (“There goes a zebra!”) than in its absence (“Let’s visit the zebras in the zoo”). Moreover, differences in this kind of input quality correlated with the size of the children’s vocabulary three years later.
It is already known that the quantity of words that children hear is an important determinant of their subsequent vocabularies, both for types (different words) and tokens (number of words heard, including repetitions). These quantity differences are correlated with socio-economic status (SES), with children from low-SES homes typically exposed to fewer words early in development. In this research, although the quantity of words differed as a function of SES, input quality did not. The authors suggest 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.
Source: Quality of Early Parent Input Predicts Child Vocabulary 3 Years Later (2013), Proceedings of the National Academy of Sciencesof the United States of America, 110(28).