arXiv:2604.17982cs.CVcs.CL2026-04被引 2

通过分阶段自奖励机制,动态抑制视觉语言模型的幻觉生成。

Mitigating Multimodal Hallucination via Phase-wise Self-reward

论文配图:Mitigating Multimodal Hallucination via Phase-wise Self-reward
图 1 · 摘自论文原文
  • 根据幻觉出现的阶段性特征,设计分阶段自奖励解码策略。
  • 在五项评测中使LLaVA-1.5-7B幻觉率降低50.0%。
  • 无需外部标注,适合追求高效准确的部署场景。

大型视觉语言模型(LVLM)仍存在视觉幻觉问题,即生成内容与视觉输入不一致。现有方法或依赖大规模标注数据微调,计算开销大;或采用静态后处理策略,忽略幻觉动态演化过程。为此,我们提出一种新的自奖励框架,可在推理时无监督地动态缓解幻觉。实证发现,视觉幻觉呈现分阶段动态模式,每阶段语义开始时达到峰值。基于此,我们提出PSRD(分阶段自奖励解码),利用分阶段自奖励信号实时纠正幻觉。为降低解码中重复自评估的成本,我们将幻觉引导信号从LVLM蒸馏为轻量级奖励模型,该模型在解码过程中提供即时干预指导,实现精准幻觉抑制。PSRD显著将LLaVA-1.5-7B的幻觉率降低50.0%,并在四个LVLM上跨五项幻觉评测基准优于现有后处理方法。进一步分析表明,该方法有效抑制幻觉传播,且在性能与效率间实现可控平衡。

原文摘要 · Abstract (English)

Large Vision-Language Models (LVLMs) still struggle with vision hallucination, where generated responses are inconsistent with the visual input. Existing methods either rely on large-scale annotated data for fine-tuning, which incurs massive computational overhead, or employ static post-hoc strategies that overlook the dynamic nature of hallucination emergence. To address these, we introduce a new self-rewarding framework, enabling dynamic hallucination mitigation at inference time without external supervision. On the empirical side, we reveal that visual hallucination exhibits phase-wise dynamic patterns, peaking at the onset of each semantic phase. Drawing on these insights, we propose \textbf{PSRD} (\textbf{Phase-wise \textbf{S}elf-\textbf{R}eward \textbf{D}ecoding) for online hallucination correction guided by phase-wise self-reward signals. To reduce the cost of repeated self-evaluation during decoding, we distill the hallucination guidance signal from LVLMs into a lightweight reward model. The reward model subsequently provides on-the-fly guidance for targeted intervention during the decoding process, enabling precise hallucination suppression. The proposed PSRD significantly reduces the hallucination rate of LLaVA-1.5-7B by 50.0% and consistently outperforms existing post-hoc methods across five hallucination evaluation benchmarks for four LVLMs. Further analysis confirms that PSRD effectively mitigates hallucination propagation and achieves a highly controllable trade-off between strong performance and inference efficiency.

幻觉抑制自奖励视觉语言模型推理优化

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