The Emergence of Phonological Categories

While phonological features are often assumed to be innate and universal (Chomsky and Halle, 1968), recent work argues for an alternative view that phonological features are emergent and acquired from linguistic input (e.g., Dresher, 2004; Mielke, 2008; Clements and Ridouane, 2011). This dissertation provides support for the emergent view of phonological features and proposes that the structure of the lexicon is the primary driving force in the emergence of phonological categories. Chapter 2 reviews the relevant developmental and theoretical literature on phonological acquisition and offers a reconsideration of the experimental findings in light of a clear distinction between phonetic and phonological knowledge. Chapter 3 presents a model of phonological category emergence in first language acquisition. In this model, the learner acquires phonological categories through creating lexically meaningful divisions in the acoustic space, and phonological categories adjust or increase in number to accommodate the representational needs of the learner\u27s increasing vocabulary. A computational experiment was run to test the validity of this model using acoustic measurements from the Philadelphia Neighborhood Corpus as the input. To provide evidence in support of a lexically based acquisition model, Chapter 4 uses the Providence Corpus to investigate developmental patterns in phonological acquisition. This corpus study shows that lexical contrast, not frequency, contributes to the development of production accuracy on both the word and phoneme levels in 1- to 3-year-old English-learning children. Chapter 5 extends the phonological acquisition model to study the role of lexical frequency and phonetic variation in the initiation and perpetuation of sound change. The results indicate that phonological change is overwhelmingly regular and categorical with little frequency effects. Overall, this dissertation provides substantive evidence for a lexically based account of phonological category emergence