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Poster Session C: Friday, August 15, 2:00 – 5:00 pm, de Brug & E‑Hall

Speaker-Specific Semantic Priors Enhance Both Expected and Unexpected Speech Across Processing Levels

Fabian Schneider¹, Helen Blank; ¹Universität Klinikum Eppendorf // University Hospital Eppendorf

Presenter: Fabian Schneider

Predictive processing is fundamental to speech perception, yet how priors shape neural representations at different hierarchical levels remains debated. Here, we investigate how humans combine expectations about what another person is going to talk about, i.e., speaker-specific semantic priors, with ambiguous sensory inputs. Using a combination of stimulus reconstruction models, representational similarity analysis, and single-trial encoding models of EEG responses, we show two complementary processes of speaker-specific semantic priors: sharpening of low-level acoustic representations, pulling them towards the expected acoustic signal and that prediction errors only at higher levels of the neural hierarchy, signaling semantic surprisal. Critically, speaker-specific priors were not applied when incoming words clearly deviated, indicating flexibility as a function of their relative likelihood. Together, these findings provide evidence for a unified theory of predictive processing in the brain in which priors enhance both expected and unexpected information at different levels of the processing hierarchy.

Topic Area: Language & Communication

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