Metaphor is a problem for natural language knowledge acquisition systems. Experts will make utterances based upon domain metaphors whichthe acquisition system ma y not possess. A n approach is presented whichuses knowledge about previously understood metaphors to process new uses.This approach is contrasted with several formal proposals for metaphorunderstanding which do not use explicit knowledge about metaphors. Asystem for representing metaphorical knowledge, as part of a generalknowledge representation language, has been built. A knowledge acquisition system, UCTeacher, is described which can process newly encounteredmetaphors using knowledge of the domain and explicit knowledge abouthow similar metaphors have been used before. A detailed example from thesystem is presented.

This project is intended to ascertain the role of conventionality in the use of metaphors in natural language processing. It examines the relationship between the degree of conventionality of a metaphor and the degree of difficulty in processing metaphorical meanings. The overall purpose is to obtain evidence regarding the metaphoric knowledge approach (Martin 1990) which asserts that the interpretation of novel metaphors can be accomplished through systematic extension, elaboration, and combination of knowledge about already well-understood metaphors. Subjects were tested on parsing sentences with different degrees of metaphorical novelty. Reaction times along with their responses were analyzed. The results suggest that a) degrees of conventionality in metaphorical use have a significant effect on the processing of the metaphor, b) degrees of novelty are proportionally related to the degrees of difficulty in processing, and c) conventional metaphors are as privileged in sentence processing as the "literal meaning" uses.