Paper Detail

MLLMs Hallucinate when Information Distribution Drifts in Synergy Heads

Meng'en Qin, Junye Chen, Jucheng Liu, Youlu Xing, Song Wang, Ruize Han

huggingface Score 10.0

Published 2026-09-05 · First seen 2026-09-21

General AI

Abstract

Multimodal Large Language Models (MLLMs) often struggle with hallucinations, thus hindering their reliable practical applications. Existing attention-based mitigation methods mainly rely on indirect signals (e.g., attention weights) that fail to accurately reflect the actual information shift underlying hallucination generation. In this paper, we propose HEAL, Head-lEvel information disentAnglement and caLibration for identifying and mitigating hallucinations. HEAL first employs causal noise intervention on multi-head outputs to filter out causally redundant heads. Subsequently, it disentangles information distribution within the remaining heads via the counterfactual Difference-in-Differences, categorizing heads into four types. Through analysis, we observe: hallucinations happen when information distribution drifts away from a healthy equilibrium in synergy heads, not strongly correlated with the quantity or strength of modality-specific heads. Motivated by this insight, HEAL injects dynamic information calibration factors into the value vectors of synergy heads, and actively regulates visual-language dependencies, steering the output distribution towards factual evidence. Extensive experiments demonstrate that HEAL effectively reduces hallucinations across multiple MLLMs, offering a simple and interpretable pathway to enhance model trustworthiness.

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BibTeX

@misc{qin2026mllms,
  title = {MLLMs Hallucinate when Information Distribution Drifts in Synergy Heads},
  author = {Meng\&\#39;en Qin and Junye Chen and Jucheng Liu and Youlu Xing and Song Wang and Ruize Han},
  year = {2026},
  abstract = {Multimodal Large Language Models (MLLMs) often struggle with hallucinations, thus hindering their reliable practical applications. Existing attention-based mitigation methods mainly rely on indirect signals (e.g., attention weights) that fail to accurately reflect the actual information shift underlying hallucination generation. In this paper, we propose HEAL, Head-lEvel information disentAnglement and caLibration for identifying and mitigating hallucinations. HEAL first employs causal noise int},
  url = {https://huggingface.co/papers/2609.09206},
  keywords = {code available, huggingface daily},
  eprint = {2609.09206},
  archiveprefix = {arXiv},
}

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