Grammatical words and the emergence of Noun and Verb categories: Evidence from production and comprehension

he distinction between Nouns and Verbs is present formally in many languages and, where it exists, is deeply embedded in the language system. It determines the way words are allowed to follow each other, the contexts in which a word is allowed to appear, the transformations that may or should be undergone by words and also the inferences that can be made about the meaning of words encountered for the first time. Children produce Nouns and Verbs practically as soon as they start talking. But do they understand that words belong to categories, do they understand the grammatical and semantic implications associated to such membership and the inter-relation between them, both in production and in comprehension? We suppose that an incipient understanding of the existence and function of these central categories develops later and in close connection with the emergence of grammatical morphemes and of the first syntactic structures. The close relationship between grammatical morphemes, syntactic structures and word categories will be considered here in light of two different sources of data (which different research teams have contributed to realise) : a) the analyses of longitudinal studies of speech production occurring naturally in parent-child interaction, in particular the study of fillers and of the phonomorphological variation in verb words, and b) results of a comprehension study testing the links between semantics, morphosyntax and word categories in which 90 children aged two to four years were led to retrieve the meaning of homophonous words on the basis of category-specific morphological markings.