Date of Award
Bruce F. Pennington, Ph.D.
Behavior Genetics, Longitudinal, Phonological Memory, Reading Disability, Speech Sound Disorder, Vocabulary
The current research investigated the relationship of phonological memory (PM) to vocabulary and syntax learning in school-age children with and without language disorders. Previous research has established that PM and broad oral language skills covary, but disagreement remains about the reason for this association. Opposing theoretical viewpoints emphasize the importance of either bottom-up (PM influences vocabulary and syntax acquisition) or top-down (vocabulary growth influences PM skill) factors. In three longitudinal studies, we tested competing bottom-up and top-down explanations of the PM-broad language link. Study 1 utilized a structural equation modeling approach to understand PM and broad language relations from age 5 to age 8 in population samples from three cultures. Final models varied by culture, with overall results supporting bidirectional relations between PM and vocabulary or syntax. Study 2 used a similar approach to investigate PM and broad language development in children with phonologically-based language disorders: speech sound disorder and reading disability. Results supported a bottom-up account in children with more substantial language delays and a bidirectional account in more mildly affected children. Study 3 used a behavior genetics approach to test for shared etiology of PM and vocabulary deficits in 5- to 8-year-old twins. We found evidence for common influences on PM and vocabulary weaknesses both within and across time. The bottom-up effect appeared to be predominantly influenced by shared genes, while the top-down affect appeared to be predominantly influenced by shared environmental experiences. Across the studies, methodological limitations prevented strong conclusions about the relation between PM and syntax. However, a clear pattern emerged concerning PM and vocabulary knowledge. The relationship of PM to vocabulary in the early school years owes to both bottom-up and top-down factors, with both effects undergoing developmental changes during this age period. We argue that the bottom-up effect gradually wanes with language development, while the top-down effect emerges as a consequence of learning to read. Future studies to further test these conclusions are proposed.
Peterson, Robin Leonhardt, "Phonological Memory and Broader Language Development: Longitudinal and Etiologic Relations" (2010). Electronic Theses and Dissertations. 902.
Received from ProQuest
Robin Leonhardt Peterson
Clinical Psychology, Developmental Psychology