Modeling the impact of phonological and semantic connectivity on early vocabulary growth

There is a long-standing debate on the extent to which early word learning is shaped by the child’s existing lexical knowledge relative to the child’s environment. We investigated the influence of the connectivity of words in the child’s lexicon (preferential attachment), the child’s environment (preferential acquisition), or between novel and known words (lure of associates) in the development of early phonological and semantic networks, using longitudinal data from 17-to-36-monthold Norwegian children. We compared the extent to which the different scenarios predicted individual children’s lexical acquisition whilst also examining the joint influence of form and meaning on vocabulary growth. Our results revealed a ‘rich-get-richer’ pattern whereby semantically well-connected words in children’s existing lexicons best predicted the likelihood of a word entering the lexicon earlier. Phonological connectivity tended to impede word learning, with leveraging effects only in early development when semantic connectivity was low. Our findings imply that words are learned more easily when they are similar to many words in meaning, but not, necessarily, in form. Furthermore, relative to previous studies examining the influence of phonological connectivity on word learning, our study highlights the importance of considering the interplay between semantics and phonology and accounting for individual differences in vocabulary development.