Word learning strategies in early childhood : mutual exclusivity across language backgrounds
Despite the challenging and ambiguous nature of word learning, infants and young children successfully learn new words at a rapid pace. As most research has focused on the word learning strategies used by monolingual English-speaking children, less is known about how bilingual children manage ambiguity and learn new words. As bilingualism is highly prevalent, the field needs to consider more thoroughly whether word learning theories developed using monolingual infants can be appropriately applied to bilingual children. In this thesis, nine eye-tracking experiments investigated whether bilingual and monolingual children differed in their use of mutual exclusivity, and their interpretation of novel labels when word learning heuristics were combined. Specifically, these experiments investigated the importance of label knowledge for mutual exclusivity (Chapter 2), and the role of animacy when novel labels were applied to familiar stimuli (Chapter 3). These experiments also investigated the interaction between mutual exclusivity, animacy and syntax (Chapter 4) and between mutual exclusivity, gaze direction and speaker language background (Chapter 5) on referent selection. Challenging prior assumptions, these experiments provided compelling evidence that bilingual and monolingual children use mutual exclusivity to the same extent and do not differ in their interpretations when different heuristics are combined. These experiments also provided comprehensive evidence of the interactions between different word learning strategies and the hierarchies that emerge. For example, children prioritised mutual exclusivity over syntactic and animacy cues, and children prioritised gaze direction over mutual exclusivity when these cues conflicted. However, children demonstrated stronger referent selection and retention when heuristics aligned. These findings provide evidence for a framework of accumulative and hierarchical cue integration in word learning, whereby children utilise hierarchies when cues conflict and aligning cues support stronger learning. Collectively, these experiments contribute a comprehensive account of how bilingual and monolingual children learn words in ambiguous contexts and the underlying interplay between word learning heuristics. This thesis also provides critical evidence that these word learning strategies are relatively robust and universal mechanisms across different language backgrounds.
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