The differential effects of intervention strategies and neighborhood density on word production

This thesis investigated differences in word production for preschool-aged children depending upon the manner in which the children learned new words. Two types of intervention strategies were explored: focused language stimulation training for parents and direct instruction by a speech language pathologist. Results showed that both intervention strategies facilitated production of novel words within an intervention session, however, words learned via focused language stimulation by parents showed greater change across intervention sessions. These results are integrated with previous findings to propose a need for involvement of speech language pathologists and parents for the most cost effective implementation of language intervention for preschool-aged children.; Additionally, this thesis explored the effects of neighborhood density, a lexical property of words, on the production of novel words and words pre-existing in the lexicons of children and adults. A developmental profile of the effects of neighborhood density was considered. Results showed that lexical representations, and thus density categories, undergo a restructuring process as children develop. Words from sparse neighborhoods were produced with greater ease, as distinguished by production duration, for preschool-aged children. Throughout the school-aged years results indicate that the mental lexicon is in a state of flux. Therefore, words were not differentiated by density category in production. As children approach adulthood, representations stabilized in memory and words from dense neighborhoods were produced with shorter duration. These results are integrated with previous findings and models of language production to propose a structural change in the mental lexicon over the course of development.