The work reported here experimentally investigates a striking generalization about vocabulary acquisition: Noun learning is superior to verb learning in the earliest moments of child language development. The dominant explanation of this phenomenon in the literature invokes differing conceptual requirements for items in these lexical categories: Verbs are cognitively more complex than nouns and so their acquisition must await certain mental developments in the infant. In the present work, we investigate an alternative hypothesis; namely, that it is the information requirements of verb learning, not the conceptual requirements, that crucially determine the acquisition order. Efficient verb learning requires access to structural features of the exposure language and thus cannot take place until a scaffolding of noun knowledge enables the acquisition of clause-level syntax. More generally, we experimentally investigate the hypothesis that vocabulary acquisition takes place via an incremental constraint-satisfaction procedure that bootstraps itself into successively more sophisticated linguistic representations which, in turn, enable new kinds of vocabulary learning. If the experimental subjects were young children, it would be difficult to distinguish between this information-centered hypothesis and the conceptual change hypothesis. Therefore the experimental "learners" are adults. The items to be "acquired" in the experiments were the 24 most frequent nouns and 24 most frequent verbs from a sample of maternal speech to 18-24-month-old infants. The various experiments ask about the kinds of information that will support identification of these words as they occur in mother-to-child discourse. Both the proportion correctly identified and the type of word that is identifiable changes significantly as a function of information type. We discuss these results as consistent with the incremental construction of a highly lexicalized grammar by cognitively and pragmatically sophisticated human infants, but inconsistent with a procedure in which lexical acquisition is independent of and antecedent to syntax acquisition.

No abstract

was presented as a digit ("zero") or as a letter (the vowel "0") amidst field items, all of which were either letters or digits. To insure the appropriate mental set, targets that were unambiguous exemplars of the appropriate categories were used in addition.

Partially conflicting results from correlational studies of maternal speech style and its effects on child language learning motivate a comparative discussion of Newport, Gleitman & Gleitman (1977) and Furrow, Nelson & Benedict (1979), and a reanalysis of the original Newport et al. data. In the current analysis the data are from two groups of children equated for age, in response to the methodological questions raised by Furrow et al.; but, in line with the original Newport et al. analysis, linguistic differences between these age-equated children are handled by partial correlation. Under this new analysis the original results reported by Newport et al. are reproduced. In addition, however, most effects of the mother on the child's language growth are found to be restricted to a very young age group. Moreover, the new analysis suggests that increased complexity of maternal speech is positively correlated with child language growth in this age range. The findings are discussed in terms of a theoretical analysis of the Motherese Hypothesis; the conditions of both learner and environment in which ‘simplified’ data could aid a learner. Finally, the results of our past work, those of Furrow et al., and those of the present analysis, are discussed as they fit into, and add to, current theorizing about the language acquisition process.

No abstract