Constraints on word meaning in early language acquisition

Very young children successfully acquire the vocabulary of their native language despite their limited information processing abilities. One partial explanation for children's success at the inductive problem word learning presents is that children are constrained in the kinds of hypotheses they consider as potential meanings of novel words. Three such constraints are discussed: (1) the whole-object assumption which leads children to infer that terms refer to objects as a whole rather than to their parts, substance, color, or other properties; (2) the taxonomic assumption which leads children to extend words to objects or entities of like kind; and (3) the mutual exclusivity assumption which leads children to avoid two labels for the same object. Recent evidence is reviewed suggesting that all three constraints are available to babies by the time of the naming explosion. Given the importance of word learning, children might be expected to recruit whatever sources of information they can to narrow down a word's meaning, including information provided by grammatical form class and the pragmatics of the situation. Word-learning constraints interact with these other sources of information but are also argued to be an especially useful source of information for children who have not yet mastered grammatical form class in that constraints should function as an entering wedge into language acquisition.