The Role of Lexical and Phonological Complexity in Early Vocabulary Growth

Matthew Carlson

From birth to school entry children’s lay a foundation of language development that will have important effects on their further development after school entry. Understanding variability between children at these crucial early stages is vital to understanding later development as well as to designing effective instruction. This study focuses on the development of phonological knowledge in the early lexicon, linking phonological structure to the particular contents of the lexicon as well as to vocabulary growth.Evidence suggests that while children favor words with frequent sound patterns, they may have difficulty acquiring highly similar words (e.g. cat/cap). The present research builds on these earlier experimental findings by tracking vocabulary growth in 1- to 5-year-olds using naturalistic speech samples. However, measures of phonological form have traditionally been based on sequences of individual phonemes, and similar words have been defined as differing in a single phoneme, such that all words differing in 2 or more phonemes as equally distant. These operational definitions are limited because they may not accurately reflect the structure of the child lexicon. Therefore, this project seeks to develop more sophisticated measures of phonological form and word similarity by incorporating higher-level phonological structures (e.g. the syllable) and by utilizing more continuous measures of similarity between words.By utilizing these innovations to analyze a large, longitudinal database, this project opens significant possibilities for understanding differences between children in language development and, importantly, subsequent success in reading. For instance, some children may have a higher tolerance for similarity or complexity in their vocabularies, which in turn may influence their success in learning to read.

About Matthew Carlson

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