A probabilistic reconciliation of coherence-driven and centering-driven theories of pronoun interpretation

Abstract

Two classic theories of pronoun interpretation have each sought to specify the relationship between pronoun use and discourse coherence, but make seemingly irreconcilable claims. According to Hobbs (1979, 1990), pronoun interpretation is not governed by an independent mechanism, but instead comes about as a by-product of utilizing world knowledge during the inferential establishment of discourse coherence relations. Factors pertaining to the grammatical form and information structure of utterances do not come into play. According to Centering Theory (Grosz, Joshi & Weinstein 1995; inter alia), on the other hand, pronoun interpretation is predominantly determined by information structural relationships within and between utterances (e.g., topic transitions) and the grammatical roles occupied by potential referents. Factors pertaining to world knowledge and the establishment of informational coherence relations do not come into play. In this paper, we describe a series of psycholinguistic experiments that ultimately suggest a reconciliation of these diverse approaches. These experiments reveal a definitive role for coherence relationships of the Hobbsian sort, demonstrating that pronoun interpretation is affected by (i) probabilistic expectations that comprehenders have about what coherence relationships will ensue, and (ii) their expectations about what entities will be mentioned next which, crucially, are conditioned on those coherence relationships. However, these experiments also reveal a role played by the topichood status of potential referents. These data are reconciled by a probabilistic model that combines the comprehender's prior coherence-driven expectations about what entities will be referred to next and Centering-driven likelihoods that govern the speaker's choice of referential form. The approach therefore situates pronoun interpretation within a larger body of work in psycholinguistics, according to which language interpretation results when top-down predictions about the ensuing message meet bottomup linguistic evidence.