Abstract

Adherence to the mutual exclusivity principle, which states that each object category can have only one name, has been demonstrated in toddlers and preschool-aged children. Studies of mutual exclusivity in bilingual children over 3.5 years have generally found a tendency to honour the principle within languages, but not across languages. To date, younger bilinguals' adherence to this principle has not been investigated. Also in question has been whether children's ability to fast map more likely reflects adherence to the mutual exclusivity principle or to the novel name-nameless category (N3C) principle. In the present cross-sectional study, monolingual and bilingual children were tested at 27 and at 35 months of age. In a first task, monolingual and bilingual children were presented with novel labels violating mutual exclusivity within a language, and were tested on their learning of the labels. Bilinguals were also administered a similar task in which mutual exclusivity was violated across languages. An assessment of the bilingual children's vocabulary production was undertaken using the MacArthur Communicative Development Inventory (Fenson et al., 1991), as well as a Quebec French adaptation developed specifically for this study. All children in this study were also administered a fast mapping task. A visual perspective-taking task was administered to determine whether bilinguals have an advantage in this parallel cognitive domain. Across both language groups, children aged 35 months honoured mutual exclusivity more than children aged 27 months. No differences were found between monolinguals and bilinguals in adherence to mutual exclusivity. In addition, bilingual children performed similarly when mutual exclusivity was violated within a language and across languages. The proportion of translation equivalents in the bilingual children's vocabulary did not relate to their mutual exclusivity task performance. Moreover, monolinguals and bilinguals did not differ in fast mapping or in perspective-taking skills. These results suggest that bilingual language experience does not have a significant impact on adherence to the mutual exclusivity principle before the age of 3 years. In addition, fast mapping performance was independent of adherence to mutual exclusivity, supporting the operation of an N3C principle. The results are discussed with reference to the nature of word-learning principles.