Development of bidirectional phono-semantic activation in toddlers

Onset Neighborhood Density Slows Lexical Access in High Vocabulary 30-Month Olds

There is consensus that the adult lexicon exhibits lexical competition. In particular, substantial evidence demonstrates that words with more phonologically similar neighbors are recognized less efficiently than words with fewer neighbors. How and when these effects emerge in the child's lexicon is less clear. In the current paper, we build on previous research by testing whether phonological onset density slows lexical access in a large sample of 100 English-acquiring 30-month-olds. The children participated in a visual world looking-while-listening task, in which their attention was directed to one of two objects on a computer screen while their eye movements were recorded. We found moderate evidence of inhibitory effects of onset neighborhood density on lexical access and clear evidence for an interaction between onset neighborhood density and vocabulary, with larger effects of onset neighborhood density for children with larger vocabularies. Results suggest the lexicons of 30-month-olds exhibit lexical-level competition, with competition increasing with vocabulary size.

Mediated semantic priming interference in toddlers as seen through pupil dynamics

Mediated priming refers to the activation of a target word by a prime word through an intermediate word. This type of priming provides behavioral evidence of between- and within-level spreading activation in the lexical system. Studies of toddlers show phonosemantic between-level mediated priming that supports a cascade of activation between different levels of processing. However, it is not clear whether the activation can spread freely within the same level. This study explored whether 24-month-old toddlers show mediated priming effects at the semantic level (e.g., cat [prime] - mouse [mediator] - cheese [target]) with a preferential looking task using an eye tracker. The results show a smaller proportion of target looking and greater pupil size in the related condition than in the unrelated condition; these effects were greater in the second half of the analysis window. We interpret these data as a spreading activation that is partially free but modulated during infancy. We also provide evidence of pupil dilation as a neurophysiological marker in a preferential looking task with priming. We discuss the results in light of the cognitive control, inhibition, and general cognitive skills of toddlers.

Lexical-Semantic Development in Bilingual Toddlers at 18 and 24 Months

An important question in early bilingual first language acquisition concerns the development of lexical-semantic associations within and across two languages. The present study investigates the earliest emergence of lexical-semantic priming at 18 and 24 months in Spanish-English bilinguals (N = 32) and its relation to vocabulary knowledge within and across languages. Results indicate a remarkably similar pattern of development between monolingual and bilingual children, such that lexical-semantic development begins at 18 months and strengthens by 24 months. Further, measures of cross-language lexical knowledge are stronger predictors of children's lexical-semantic processing skill than measures that capture single-language knowledge only. This suggests that children make use of both languages when processing semantic information. Together these findings inform the understanding of the relation between lexical-semantic breadth and organization in the context of dual language learners in early development.