Beyond the Global Scores: Fine-Grained Token Grounding as a Robust Detector of LVLM Hallucinations
- URL: http://arxiv.org/abs/2604.04863v1
- Date: Mon, 06 Apr 2026 17:07:11 GMT
- Title: Beyond the Global Scores: Fine-Grained Token Grounding as a Robust Detector of LVLM Hallucinations
- Abstract summary: Large vision-language models (LVLMs) achieve strong performance on visual reasoning tasks but remain highly susceptible to hallucination.<n>Existing detection methods rely on coarse, whole-image measures of how an object token relates to the input image.<n>We introduce a patch-level hallucination detection framework that examines fine-grained token-level interactions across model layers.<n>Our approach achieves up to 90% accuracy in token-level hallucination detection, demonstrating the superiority of fine-grained structural analysis for detecting hallucinations.
- Score: 32.1925100166762
- License: http://creativecommons.org/licenses/by-sa/4.0/
- Abstract: 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.
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