A single stage approach to learning phonological categories: Insights from Inuktitut

Brian W Dillion, Ewan Dunbar, William Idsardi

We argue that there is an implicit view in psycholinguistics that phonological acquisition is a 'two-stage' process: phonetic categories are first acquired, and then subsequently mapped onto abstract phoneme categories. We present simulations that suggest two problems with this view: first, the learner might mistake the phoneme-level categories for phonetic-level categories and thus be unable to learn the relationships between phonetic-level categories; on the other hand, the learner might construct inaccurate phonetic-level representations that prevent it from finding regular relations among them. We suggest an alternative conception of the phonological acquisition problem that sidesteps this apparent inevitability, and present a Bayesian model that acquires phonemic categories in a single stage. Using acoustic data from Inuktitut, we show that this model reliably converges on a set of phoneme-level categories and phonetic-level relations among subcategories, without making use of a lexicon.