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Presupposition processing in discourse under memory and inference constraints: an fMRI study
Poster Session B, Wednesday, September 30, 4:30 - 6:30 pm, Wangari Maathai
Susanne Dietrich1, Verena, C. Seibold1, Bettina Rolke1; 1University of Tübingen
Discourse understanding often depends on retrieving or constructing contextual information to establish coherent referential relations. Processing presuppositions (PSPs), linguistic expressions carrying background information, is particularly challenging when their referential conditions are unfulfilled. In such cases, coherence may either fail to emerge or may be restored through accommodation, whereby the context is updated via bridging inferences that link an utterance to plausible background knowledge. How the brain adaptively manages these inferences under varying memory constraints remains largely unknown. In an fMRI–behavioral experiment, we investigated PSP processing in two context types: (a) memory-based contexts, in which referential distance between the PSP trigger (definite and indefinite determiners) and its corresponding referent was systematically varied, and (b) inference-based contexts, in which referents were not explicitly mentioned, and contextual plausibility was manipulated. Across both context types, PSP consistency was manipulated via determiner type and referential status: In memory-based contexts, a definite determiner referred either to an existing referent (intact) or to a negated non-existent referent (violated). In inference-based contexts, a definite determiner presupposed a referent not previously mentioned (violated), whereas an indefinite determiner introduced a newly established referent (intact). Participants listened to sentences during fMRI acquisition and judged their coherence relative to the preceding context. Behaviorally, in memory-based contexts, PSP violations were judged as less incoherent when referential distance increased. In inference-based contexts, coherence judgments were mainly influenced by plausibility, with a small but significant effect of PSP consistency. For fMRI analyses, BOLD responses were time-locked to the PSP trigger. In memory-based contexts, PSP consistency modulated activity in the left inferior frontal gyrus (IFG) and right supramarginal gyrus (SmG), reflecting working-memory demands and integration, whereas referential distance engaged executive control regions including the pre-supplementary motor area (pre-SMA) and middle frontal gyrus (MFG). In inference-based contexts, plausibility violations recruited the bilateral insula and subcortical thalamo-striatal regions, which showed correlation with coherence judgments, indicating adaptive allocation of attentional and interpretive resources during discourse processing. Direct contrasts further revealed a dissociation between processing modes: memory-based processing was associated with integration-related control regions (e.g., SmG), whereas inference-based processing recruited semantic and episodic memory regions (e.g., Precuneus) supporting constructive inference. These findings indicate that PSP processing is supported by a flexible interaction between memory areas and inference processing neuronal areas.
Topic Areas: Meaning: Discourse and Pragmatics,