Relations Among Word Meanings in Early Lexical Development

When deriving the meanings of individual words, children must also discern the relations among words. To ascertain how children interpret such relations, we taught twelve 2-year-olds novel count nouns for related but unfamiliar objects. Although we never specified the relations among words, children's interpretation of the relations was mediated by the similarity of the objects. For dissimilar objects, children interpreted the words as mutually exclusive. For more similar objects, children's performance was consistent with a hierarchical interpretation of meaning. Thus, by 2 years of age, children have the conceptual and lexical abilities necessary for the establishment of hierarchical inclusion relations. The significance of this finding for theories of lexical and conceptual development is discussed.