When knowing only one word for "car" leads to weak application of mutual exclusivity

From a very young age, monolingual children assume their language has no synonyms, or use the principle of mutual exclusivity (only one label per object). In contrast, bilingual children often accept more novel synonyms than monolinguals. One possible explanation for this difference is the lexicon structure hypothesis: having synonyms (across languages) in the lexicon reduces adherence to mutual exclusivity. The purpose of this study is to test the lexicon structure hypothesis by comparing three- to five-year-old children who speak either Canadian French or English. Canadian French allows more synonyms than English. French-speaking children should therefore accept more novel synonyms than English-speaking children. The children did a disambiguation task, choosing whether a familiar or an unfamiliar object was the referent of a novel word (e.g., moli). Surprisingly, the French-speaking children accepted significantly fewer novel synonyms than English-speaking children. However, they accepted the most synonyms for objects that had synonyms in French but they did not know both synonyms. These results support a modified version of the lexicon structure hypothesis, one that accounts for children's weak access to synonyms.