UCLA

Research suggests that child language development trajectories, and specifically, the size and content of children's vocabularies, depend in large part on input from social partners like parents or caregivers. However, the existing literature lacks detailed descriptions of the types and frequencies of social language cues provided to children. In order for children to learn language from social input, they must have access to frequent, predictive, and informative cues. This dissertation describes the characteristics of parent-to-child social input, and examines the role of this input in supporting children's language development.

A set of two studies investigated (1) what social cues for language development are provided by parents in naturalistic environments, and (2) whether parents facilitate their children's language development by providing knowledge-targeted and informative social cues. In Study 1, naturalistic parent-child interactions filmed at the child's home were coded for variables including parent gesture, syntax, and object labeling, and quantity of parent and child speech. Children were 18 to 30 months old. Results showed that parents provided children with verbal and non-verbal social cues facilitating acquisition of object labels, and these cues co-occurred with the presence of the object being named; for example, parents pointed to objects while naming them, and created saliency for target words through syntactic framing.

In Study 2, conducted in a child laboratory, mother-child dyads were provided with toy ("target") objects and animals whose labels were either known, unknown, or somewhat known to the child. Mother-child interactions were again coded for maternal gesture, syntax, and object labeling, and quantity of both maternal and child speech. Children were 18 to 22 months old. Results showed that the strength of correlations between child overall vocabulary knowledge (measured by a parent report pre-test) and maternal pointing to a given set of objects varied by child familiarity with those objects. Results also showed that mothers changed their input to match their children's knowledge; for example, they compared target objects to absent objects more often when the target object was unknown to the child. These findings add to evidence that parental social cues provide strong support for child vocabulary development.