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Distinct Neural Pathway for Knowledge- and Event-Based Social Impression Formation

Poster Session C - Sunday, March 8, 2026, 5:00 – 7:00 pm PDT, Fairview/Kitsilano Ballroom

Akiho Kamo¹ (), Moe Mihara¹, Takashi Tsukiura¹; ¹Kyoto University

Trustworthiness impressions are shaped not only by first encounters but also by memories that accumulate over time. Previous functional neuroimaging evidence implicates the dorsomedial prefrontal cortex (dmPFC) in impression formation, the medial temporal lobe (MTL) and retrosplenial cortex (RSC) in episodic memory, and the anterior temporal lobe (ATL) in social knowledge as semantic memory. However, little is known about how these systems support trustworthy judgments grounded in episodic and semantic memories for other people. We used functional MRI (fMRI) to scan young adults while they judged others’ trustworthiness based on social traits learned as knowledge-based memories and on hypothetical actions learned as event-based memories, acquired before scanning. Univariate analyses showed significant ATL activation during knowledge-based judgments, and significant RSC activation during both knowledge- and event-based judgments. Multivariate pattern analysis (MVPA) indicated that activity patterns in ATL and RSC represented trustworthiness for both memory types, whereas activity patterns in the parahippocampal cortex (PHC) represented event-based trustworthiness only. Additionally, activity patterns in dmPFC reliably classified trustworthy versus untrustworthy impressions. Functional connectivity analyses revealed stronger dmPFC coupling with ATL and RSC during knowledge-based judgments, and with PHC, hippocampus, and RSC during event-based judgments. Taken together, these findings suggest that dmPFC integrates social knowledge supported by ATL with event information supported by MTL to construct trustworthiness impressions for other people from long-term memory. These fMRI results advance a systems-level account of how mnemonic sources shape social evaluation and highlight distinct representational and connectivity signatures for knowledge- and event-based routes to trustworthiness for other people.

Topic Area: LONG-TERM MEMORY: Episodic