Epistemic Familiarity is Associated With Belief Stability in Large Language Models

Samantha Dies, Courtney Maynard, Germans Savcisens, Tina Eliassi-Rad


Abstract
Large language models (LLMs) are widely used as information sources, yet small changes in semantic assumptions can destabilize their beliefs. We introduce P-StaT (Perturbation Stability of Truth), a framework for evaluating belief stability under matched semantic perturbations in both representational and behavioral settings. Across 21 LLMs and three domains, we compare perturbations involving familiar Fictional statements against synthetically generated and unfamiliar Synthetic statements. Unfamiliar Synthetic perturbations generally induce greater epistemic instability than familiar Fictional perturbations, with behavioral belief retraction rates frequently exceeding 50%. Finally, exploratory clustering analyses reveal recurring themes among retracted statements, including ambiguity, technical terminology, and obscure concepts. These results show that epistemic familiarity is systematically associated with stability under semantic reframing, suggesting that stability-based analyses can complement accuracy-based benchmarks when evaluating LLM robustness and reliability. Code and data are available at https://github.com/samanthadies/P-StaT.
Anthology ID:
2026.findings-emnlp.532
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
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SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
11150–11175
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.532/
DOI:
Bibkey:
Cite (ACL):
Samantha Dies, Courtney Maynard, Germans Savcisens, and Tina Eliassi-Rad. 2026. Epistemic Familiarity is Associated With Belief Stability in Large Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 11150–11175, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Epistemic Familiarity is Associated With Belief Stability in Large Language Models (Dies et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.532.pdf