Relations between vocabulary growth and indications of grammatical development in the Serbian CDIs data

Abstract

Adaptations of the MacArthur-Bates’ CDIs for the Serbian language have provided pilot data on 126 children of 8-30 months of age. To explore the validity of data analyses were conducted on vocabulary size as well as on the items dedicated to grammatical development. The results showed a steady increase by age in receptive and expressive vocabulary size on both CDI questionnaires in all semantic domains. In contrast to early vocabularies typical for young children (up to 21 months of age) primarily composed of nouns, the elder children (from 22 months onwards) gradually made the transition to the usage of verbs, adverbials, and other close-classed function words. Steady growth was also found in older children on items dedicated to further grammatical development (the transition to the 3rd year of age). Moreover, complex morphological properties of Serbian language enabled exploration of the relationship between the vocabulary size and the growth of grammar at three different types of indications – how vocabulary growth is related with the use of functional words, the use of morphological marking, and the syntactic complexity of utterances in children’s production. The results showed that grammatical development is closely related to the increase in children's productive vocabulary size. Vocabulary size appeared to be a better predictor of early usage of morphologically marking than of syntactic complexity of utterances and the usage of functional words. Even though conducted on a limited sample, the analyzes also revealed bimodal distribution across age in the relationship between vocabulary and grammatical growth thus supporting previous findings that the dependence changes over developmental course.