OViP: Online Vision-Language Preference Learning with Hallucination-Targeted Negatives

Shujun Liu, Siyuan Wang, Zejun Li, Jianxiang Wang, Zeng Cheng, Xuanjing Huang, Zhongyu Wei


Abstract
Large vision-language models (LVLMs) remain prone to hallucination. While recent visual Direct Preference Optimization (DPO) methods try to fix this by contrasting positive images with heuristic or offline negatives for the same correct response. We show that such negatives are mostly "trivial": the model already assigns near-zero probability to the correct response, so the resulting gradient is uninformative or even spuriously misdirected. We propose OViP, an on-policy framework that synthesizes negative images on the fly from the model’s own hallucinated responses via a diffusion prior, producing semantically misaligned yet still high-likelihood negatives. Across five hallucination and four general benchmarks, OViP achieves better hallucination mitigation on LLaVA-1.5 series and Qwen2.5-VL-3B, while being 2 times more compute-efficient than SIMA and incurring no degradation on general capabilities.
Anthology ID:
2026.findings-emnlp.674
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:
14142–14167
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URL:
https://aclanthology.org/2026.findings-emnlp.674/
DOI:
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Cite (ACL):
Shujun Liu, Siyuan Wang, Zejun Li, Jianxiang Wang, Zeng Cheng, Xuanjing Huang, and Zhongyu Wei. 2026. OViP: Online Vision-Language Preference Learning with Hallucination-Targeted Negatives. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 14142–14167, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
OViP: Online Vision-Language Preference Learning with Hallucination-Targeted Negatives (Liu et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.674.pdf