Broadening and narrowing in lexical development: How relevance theory can account for children's overextensions and underextensions

The paper examines the parallels between young children's overextensions and underextensions and lexical pragmatic processes of broadening and narrowing as described in relevance theory. I argue that cases of overextension involve the communication of ad-hoc concepts constructed by the broadening of lexically encoded concepts and cases of underextension have close parallels with lexical narrowing. While overextension is viewed as a communicative strategy consistent with the Communicative Principle of Relevance, underextension is seen as arising in cognition or comprehension, as the child hypothesises about the boundaries of the acquired concept. There appear to be two types of overextensions: those which rely on shared properties (e.g. of shape) extracted from the encyclopaedic entries for concepts, and those which exploit shared information from the logical entries. Similarly, there seem to be two types of underextension. The first is characterised by the lack of a logical entry for a concept and the second involves concepts whose logical entries have been illegitimately enriched with encyclopaedic information. I show in the final section that this analysis has important theoretical implications for relevance theory, especially regarding the status of logical and encyclopaedic entries in both lexically encoded concepts and ad-hoc concepts.