Proceedings of the Annual Meeting of the Cognitive Science Society

Current, rule-based theories of grammar do not provide much insight into how languages can develop new behaviors over time. Yet, textual data indicate that languages usually evolve new grammatical patterns by gradually extending existing ones. I show how a grammar model that is sensitive to prototype structure can model innovation as a process of extrapolation along salient dimensions of the category clusters. A Connectionist network provides a usefully interpretable implementation. Confirming evidence comes from a study of the development of English be going to as a marker of future tense.