Submission 402
The Suitcase that Didn’T Exist: fMRI Evidence for Adaptive Mechanisms in Presupposition Processing
SymposiumTalk-02
Presented by: Susanne Dietrich
Discourse understanding often requires retrieving or constructing context to establish coherent reference relations. Presuppositions (PSPs), linguistic expressions carrying background information, pose a challenge when their referential conditions are unfulfilled. Specifically, coherence may either not be established or be restored through accommodation (e.g., bridging). How the brain adaptively manages these demands under varying memory constraints remains largely unknown.
In an fMRI-behavioral experiment, we investigated two memory processes and PSP types: (a) memory-based contexts, where referential distance varied and triggered existence PSPs, and (b) inference-based contexts, where referents were not explicitly mentioned and contextual plausibility varied, targeting novelty PSPs. Participants judged the coherence of a test sentence relative to the preceding context. Coherence judgments in memory contexts showed that PSP violations were judged as less incoherent when referents appeared more distant, indicating higher working-memory load. In inference contexts, coherence judgments were mainly influenced by plausibility, with a small but significant PSP consistency effect.
For fMRI analysis BOLD responses were time-locked to the PSP trigger. In memory contexts, PSP consistency modulated the left IFG and right supramarginal gyrus (SmG), reflecting working-memory load and integration, while referential distance engaged executive regions such as pre-SMA and middle frontal gyrus. In inference contexts, plausibility violations recruited the salience network (bilateral insula, right SmG) and subcortical basal ganglia-thalamus loops, indicating adaptive allocation of attentional and interpretive resources.
These results highlight the involvement of the salience network in conflict detection and executive regions in maintaining discourse coherence, showing that PSP processing is dynamically shaped by memory constraints.