There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
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.