arXiv:2604.04863cs.CV2026-04中稿 · CVPR被引 3

通过细粒度注意力分析,精准识别大模型幻觉生成的词汇。

Beyond the Global Scores: Fine-Grained Token Grounding as a Robust Detector of LVLM Hallucinations

  • 分析每层中词元与图像块的局部交互,捕捉幻觉特征。
  • 在多个数据集上实现最高90%的幻觉检测准确率。
  • 适合关注大模型可靠性与可解释性的研究人员。

大型视觉语言模型(LVLMs)在视觉推理任务中表现强劲,但仍易产生幻觉。现有检测方法主要依赖全局层面的物体词元与输入图像的相关性度量,但该策略存在局限:幻觉词元可能在多个局部区域表现出微弱但分散的相关性,其总和形成看似高的整体相关性,从而逃避现有全局检测器。我们基于一个关键观察:真实词元必须在特定图像区域内有强关联。据此提出一种基于图像块级别的幻觉检测框架,分析模型各层中的细粒度词元-图像交互。分析揭示幻觉词元的两个特征:(i) 注意力分布弥散、非定位;(ii) 与任何视觉区域均无语义对齐。基于此,我们设计了一种轻量且可解释的检测方法,结合图像块级统计特征与隐藏层表示。该方法在词元级别幻觉检测上达到最高90%准确率,证明细粒度结构分析在检测幻觉上的优势。

原文摘要 · Abstract (English)

Large vision-language models (LVLMs) achieve strong performance on visual reasoning tasks but remain highly susceptible to hallucination. Existing detection methods predominantly rely on coarse, whole-image measures of how an object token relates to the input image. This global strategy is limited: hallucinated tokens may exhibit weak but widely scattered correlations across many local regions, which aggregate into deceptively high overall relevance, thus evading the current global hallucination detectors. We begin with a simple yet critical observation: a faithful object token must be strongly grounded in a specific image region. Building on this insight, we introduce a patch-level hallucination detection framework that examines fine-grained token-level interactions across model layers. Our analysis uncovers two characteristic signatures of hallucinated tokens: (i) they yield diffuse, non-localized attention patterns, in contrast to the compact, well-focused attention seen in faithful tokens; and (ii) they fail to exhibit meaningful semantic alignment with any visual region. Guided by these findings, we develop a lightweight and interpretable detection method that leverages patch-level statistical features, combined with hidden-layer representations. Our approach achieves up to 90% accuracy in token-level hallucination detection, demonstrating the superiority of fine-grained structural analysis for detecting hallucinations.

幻觉检测视觉语言模型注意力分析

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