Do the Right Thing ... but Expect the Unexpected

Dale and Reiter (1995) have recently discussed the nature of referring expression generation, focusing on the case of definite noun phrases. In particular, they consider Gricean approaches, whereby the speaker is supposed to take into account likely inferences by the hearer, in accord with Gricean maxims, and select the generated NP accordingly, so as to avoid false or misleading inferences (Joshi, 1982). They observe that previous accounts (including their own) have attempted to optimise the generated noun phrase, making it as brief as possible, within the constraints of accurately distinguishing the intended referent from any other candidate referents. For instance, consider a situation containing three animals: one small white cat and two dogs, one large and black, and the other small and white. It is usually assumed that an optimal description of the first dog is either the large dog or the black dog, whereas the large black dogwill be sub-optimal, since it contains two adjectives where one will do; it is longer than strictly necessary, and suffers from a degree of redundancy (Dale, 1992; Reiter, 1990). However, Dale and Reiter argue that the previous algorithms proposed for this task are computationally inefficient, and that the task itself must be reconsidered. In particular, they suggest that there is substantial psycholinguistic evidence that people don’t Human Communication Research Centre, University of Edinburgh, 2 Buccleuch Place, Edinburgh EH8 9LW, Scotland