UNIDIRECTIONAL MEANING CHANGE WITH METAPHORIC AND METONYMIC INFERENCING

Grammaticalization is an important factor in language evolution as it may contribute to the emergence and the evolution of grammatical forms (Heine & Kuteva, 2002; Hurford, 2003). Considering what kinds of dispositions in cognitive mechanism can induce grammaticalization is significant in studying the origin of language. Hashimoto and Nakatsuka (2006) showed that two designs of meaning structure, “pragmatic extension” and “cooccurrence”, were effective to realize unidirectional meaning changes, the centric feature of grammaticalization, by constructing a computational model of grammaticalization. This model is made based on the iterated learning model of Kirby (2002), in which a speaker having a set of production rules utters descriptions of some situations composed of some elemental meanings to a hearer who tries to construct hidher own rule set. In this paper, we analyze the relationships of the two designs with metaphoric and metonymic inferencing, the important mechanisms for meaning change. The design of meaning structure named “pragmatic extension” is the followings: the speaker can use forms F2 and F3 representing elemental meanings M2 and M3. respectively, in order to describe another elemental meaning M I . For example, in order to describe a meaning of (go), the forms representing (run) and (walk) can be utilized. In our simulations, this setting boosts the frequency of meaning changes in which the source is (go} and the targets are the other meanings including but not limited to (run) and (walk). Note that all meaning changes have virtually the same frequencies without this setting. Since the situational meaning is denoted as ([tense]verb(agent, pat ient)) in the model, (go}, (run) and (walk} are in predefined paradigmatic relations. The current setting of “pragmatic extension” means that the speaker recognizes the relevance among specific meanings in the paradigmatic relations and (go) as the core of those meanings. The speaker applies a production rule M2 -+ F2 to M I extensively based on the recognition of the relevance of M2 to M I . This process corresponds to the metaphoric inferencing in which expressions in a meaning domain are applied to another domain based on the relevance between the domains.