The Lexical Composition of Bilingual vs. Monolingual Parental Verbal Input & its Influence on Child Vocabulary

Parental verbal input is a significant resource for children's early childhood vocabulary development. As bilingual children differ from their monolingual peers in vocabulary size and their use of nouns, verbs, and descriptors, we suspected that parental input during early language acquisition may play a role in facilitating these differences in bilingual language. We hypothesized that there would be a group difference between monolingual and bilingual parents in the lexical categories (nouns, verbs, adjectives, and adverbs) of their verbal input during the play session. The study also focused on a specific “looking while labeling” moment, the Visually Optimal Naming Moment (VONM), referring to the instances of child attention on the target references with parent-appropriate labeling simultaneously. Since these naming moments facilitate word learning in children, we also hypothesized that there would be a group difference in lexical categories during the VONMs. Lastly, we hypothesized that The amount of lexical composition in parental phrases would positively correlate with the child's vocabulary size. The study used 10 typically-developing monolingual English-speaking parent-child dyads (M=15.05 months), and 10 English-Spanish bilinguals (M=14.93 months). The dyads participated in a short play session while playing with toys and wearing head-mounted eye-tracking devices, and the parents also filled out the MacArthur-Bates Development Inventory for their children's vocabulary. After annotating the children's gaze and parent's utterances, we found that there was no group difference in lexical categories during parent verbal input, but the number of adjectives in parent input did correlate positively with the children's receptive vocabularies.