MARD: A Multi-Agent Reinforced Debiasing Framework for Large Language Models

Xiaoqing Cheng, Tao Liu, Tian Lan, Jinwang Song, Chen Chen, Hongying Zan, Wen Zhang, Huajun Chen


Abstract
Mitigating social bias in large language models (LLMs) has become an increasingly important research objective. However, existing methods often rely on prompt-level control or optimize bias-aware guidance and final prediction within a single model, which may lead to coupled optimization and task interference. To address these limitations, we propose MARD, a Multi-Agent Reinforced Debiasing framework that decomposes debiasing into two role-specialized agents. The Bias-Guard Agent identifies stereotype cues and generates bias-control guidance, while the Evidence-Decision Agent produces evidence-grounded predictions without relying on identity-based assumptions. MARD further introduces retrieved group-related references as negative warning signals to expose potential stereotype cues, and adopts an alternating GRPO optimization strategy to improve role specialization. Experiments on five datasets across four task types demonstrate that MARD achieves strong overall debiasing performance. Further analyses highlight the effectiveness of role decoupling, alternating optimization, format control, and retrieved warning references.
Anthology ID:
2026.emnlp-main.2630
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
59812–59823
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2630/
DOI:
Bibkey:
Cite (ACL):
Xiaoqing Cheng, Tao Liu, Tian Lan, Jinwang Song, Chen Chen, Hongying Zan, Wen Zhang, and Huajun Chen. 2026. MARD: A Multi-Agent Reinforced Debiasing Framework for Large Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 59812–59823, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MARD: A Multi-Agent Reinforced Debiasing Framework for Large Language Models (Cheng et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2630.pdf