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Main Authors: Jia, Kaidi, Lin, Yujie, Yang, Chengyi, Ma, Jiayao, Su, Jinsong
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.08031
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author Jia, Kaidi
Lin, Yujie
Yang, Chengyi
Ma, Jiayao
Su, Jinsong
author_facet Jia, Kaidi
Lin, Yujie
Yang, Chengyi
Ma, Jiayao
Su, Jinsong
contents Vision-language models (VLMs) raise growing concerns about privacy, copyright, and bias, motivating machine unlearning to remove sensitive knowledge. However, existing methods primarily fine-tune the language decoder, leading to superficial forgetting that fails to erase underlying visual representations and often introduces object hallucination. We propose HFRU, a reinforcement unlearning framework that operates on the vision encoder for deep semantic removal. Our two-stage approach combines alignment disruption with GRPO-based optimization using a composite reward, including an abstraction reward that encourages semantically valid substitutions and mitigates hallucinations. Experiments on object recognition and face identity tasks show that HFRU achieves over 98% forgetting and retention performance, while introducing negligible object hallucination, significantly outperforming prior methods.Our code and implementation details are available at https://github.com/XMUDeepLIT/HFRU.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08031
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Object Hallucination-Free Reinforcement Unlearning for Vision-Language Models
Jia, Kaidi
Lin, Yujie
Yang, Chengyi
Ma, Jiayao
Su, Jinsong
Computer Vision and Pattern Recognition
Vision-language models (VLMs) raise growing concerns about privacy, copyright, and bias, motivating machine unlearning to remove sensitive knowledge. However, existing methods primarily fine-tune the language decoder, leading to superficial forgetting that fails to erase underlying visual representations and often introduces object hallucination. We propose HFRU, a reinforcement unlearning framework that operates on the vision encoder for deep semantic removal. Our two-stage approach combines alignment disruption with GRPO-based optimization using a composite reward, including an abstraction reward that encourages semantically valid substitutions and mitigates hallucinations. Experiments on object recognition and face identity tasks show that HFRU achieves over 98% forgetting and retention performance, while introducing negligible object hallucination, significantly outperforming prior methods.Our code and implementation details are available at https://github.com/XMUDeepLIT/HFRU.
title Object Hallucination-Free Reinforcement Unlearning for Vision-Language Models
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.08031