Do infants really learn phonetic categories?
Sharon Goldwater (University of Edinburgh) (joint work with Naomi Feldman, Thomas Schatz, Emmanuel Dupoux, Xuan-Nga Cao)
Tuesday March 19
G.32, 7 George Square
Early changes in infants’ ability to perceive native and non-native speech sound contrasts is typically attributed to their developing knowledge of phonetic categories. I will argue, however, that there is little direct evidence of early category knowledge, and that alternative accounts of early perceptual changes should be considered. I will propose a general account, unsupervised representation learning, that draws on approaches standardly used in machine learning. I will then describe a specific model within this framework that successfully simulates the different developmental trajectories of Japanese-learning and American English-learning infants with respect to the [r]-[l] contrast. Nevertheless, the representations learned by this model lack several necessary conditions of phonetic categories. These results demonstrate that observed changes in infant perception could occur in the absence of phonetic categories, prompting a potential re-examination of the timeline of early language acquisition.