Targeted Decoding Intervention for Persona Inconsistency Hallucination Mitigation in Multi-Turn Dialogue

Jie Bao, Yan Xu, Haojie Wu, Yu Gao, Xinyu Cui, Jian Zhao, Yong Liao, Zhen Chen


Abstract
Persona-driven role-playing agents tend to drift from their assigned profile or contradict their earlier statements as the dialogue lengthens, a faithfulness failure we call persona inconsistency hallucination. Existing inference-time mitigations apply reward-guided decoding uniformly at every token, while we observe that inconsistency risk is concentrated on a small subset of turns and is locally predictable, which makes a selective intervention feasible. We propose TaDI (Targeted Decoding Intervention), a training-free method with three components: an Inconsistency Risk Predictor that gates intervention before generation, a Targeted Reward-Guided Decoding module that combines a positive profile reward with a negative commitment reward, and a Commitment Propagation Memory that tracks the agent’s prior claims across turns. We additionally introduce a Type-A/B/C violation taxonomy distinguishing profile violation, history contradiction, and commitment fabrication, used as a diagnostic for attributing where any method gains or loses. Extensive experiments show TaDI is competitive with the strongest always-on baseline while being substantially more efficient and more robust under adversarial interrogation.
Anthology ID:
2026.findings-emnlp.627
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
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
13164–13179
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.627/
DOI:
Bibkey:
Cite (ACL):
Jie Bao, Yan Xu, Haojie Wu, Yu Gao, Xinyu Cui, Jian Zhao, Yong Liao, and Zhen Chen. 2026. Targeted Decoding Intervention for Persona Inconsistency Hallucination Mitigation in Multi-Turn Dialogue. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 13164–13179, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Targeted Decoding Intervention for Persona Inconsistency Hallucination Mitigation in Multi-Turn Dialogue (Bao et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.627.pdf