Abstract
It is often claimed that irregular verbs in English are learned by memorizing associated pairs between stems and past tense forms, and hence, that frequency of an irregular verb largely determines the success of its acquisition (Pinker 1999). Yet a careful examination of the acquisition data (Marcus, Pinker, Ullman, Hollander, & Xu 1992) shows that the frequency-acquisition correlation completely breaks down when the phonological regularities in irregular past tense formation are taken into consideration. The data in fact suggest a view of learning that involves (a) the construction of phonological rules, even among the very unsystematic irregular classes, and (b) probabilistic associations between words and their corresponding rules (e.g., lose -> (-t suffixation + vowel shorteing). This talk gives acquisition evidence for this approach. Then, based on a model of word learning by Sussman & Yip (1996, 1997), we develop a computational model of sound change, which may explain, inter alia, why irreguliarty in languages is not an “imperfection”, but a necessity.

Biography
Charles Yang received his Ph.D. in computer science from MIT, and has since been teaching computational linguistics and child language at Yale. He is the author of “Knowledge and Learning in Natural Language” (Oxford University Press, 2002).