Identity-Preserving Detoxification via Local Causal Effect Ranking on Masked Diffusion Language Models

Yucheng Lin, Yue Liu, Jiaojiao Jiang


Abstract
Text detoxification should produce safer rewrites while retaining identity mentions from the original text. However, classifier-guided methods can remove identity descriptors alongside genuinely harmful content when toxicity classifiers associate identity mentions with harmfulness and guidance relies on absolute scores. We propose CIDER (Contrastive Identity-preserving Detoxification via Explicit Reference), a default-relative, margin-gated selective-guidance method for masked diffusion language models. At each selected masked position, CIDER evaluates every candidate in the admissible top-k set relative to the model-default token in the same partially decoded state and commits a non-default candidate only when the best candidate lowers the one-step proxy score by more than a preset margin. On the primary LLaDA-8B CivilComments×Jigsaw setting, CIDER improves retention by +0.06 to +0.16 over the interpolated absolute-score frontier at matched residual-toxicity levels. At the reported aggressive endpoints, the retention advantage recurs across four data pairings on LLaDA-8B and three bases on CivilComments×Jigsaw. Controlled ablations indicate that the selection rule is an important contributor to the improvement.
Anthology ID:
2026.emnlp-main.234
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
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Pages:
5360–5378
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URL:
https://aclanthology.org/2026.emnlp-main.234/
DOI:
Bibkey:
Cite (ACL):
Yucheng Lin, Yue Liu, and Jiaojiao Jiang. 2026. Identity-Preserving Detoxification via Local Causal Effect Ranking on Masked Diffusion Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 5360–5378, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Identity-Preserving Detoxification via Local Causal Effect Ranking on Masked Diffusion Language Models (Lin et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.234.pdf