Preschoolers' default assumptions about word meaning: Proper names designate unique individuals.

Ninety 4-year-olds took part in this experiment. Children heard a novel word ( e.g., X) uttered in an ambiguous sentence frame (e.g., This Y is X, where Y was a basic-level count noun, such as dog) and applied to either 1 or 2 drawings of familiar animals. This word could be construed either as a proper name (e.g., This dog is Fred) or as an adjective (e.g., This dog is red). Children were more likely to interpret the word as a proper name ( and less likely to interpret it as an adjective ) if it was applied to I than if it was applied to 2 objects. Children thus made a default assumption that, in order to be a proper name, a word should be applied to only I individual. However, children overrode this default assumption if sufficient contextual information (from additional syntactic cues) indicated that they should do so.