Language Proficiency and Lexical-Semantic Processing in Bilingual Toddlers

Abstract

Prior research suggests that language systems are not entirely separate but interact in bilingual individuals. The current study seeks to extend prior work by investigating whether or not bilingual toddlers organize vocabulary words and their meanings (i.e., lexical-semantic networks) within and across languages as early as 2 years of age. Of interest is how the words a toddler hears (i.e., language exposure) versus the words that they say (i.e., language proficiency) influence this organization of dual vocabulary systems. This study presents findings from a group of Spanish-English bilingual toddlers (N = 20, Mage = 24.65 months) to examine the association between (a) language exposure and (b) language proficiency with lexical-semantic processing. Four measures were used: the Language Exposure Assessment Tool (LEAT) captured exposure, whereas the Computerized Comprehension Task (CCT) and the English-Spanish Vocabulary Inventories (ESVI) measured vocabulary size in both languages. Lastly, eye-tracking measures assessed lexical-semantic processing within and across Spanish and English. Consistent with prior literature, results suggest that vocabulary systems interact in bilingual toddlers by 24 months of age. As a group, toddlers with larger vocabulary sizes and faster speed of word recognition in their stronger language (Spanish) demonstrated inhibition, such that they were more likely to efficiently discard words similar in meaning (i.e., semantic competitors) in order to correctly identify the target. When processing semantic relationships between words in their weaker language (English), toddlers with slower speed of word recognition demonstrated facilitation in order to continue ongoing activation of their sparse vocabulary networks. However, language exposure was not associated with lexical-semantic processing. Together these findings demonstrate that the words bilingual toddlers say and understand (and not necessarily what they hear) influence the organization of dual language systems. Ultimately, our findings contribute to the current understanding of bilingual first language acquisition and emerging theoretical models on bilingual language development.