Not All Tokens and Heads Are Equally Important: Dual-Level Attention Intervention for Hallucination Mitigation

Abstract: Large vision-LLMs (LVLMs) have shown remarkable capabilities across a wide range of multimodal tasks. However, they remain prone to visual hallucination (VH), often producing confident but incorrect descriptions of visual content. We present VisFlow, an efficient and training-free framework designed to mitigate VH by directly manipulating attention patterns during inference. Through systematic analysis, we identify three key pathological attention behaviors in LVLMs: (1) weak visual grounding, where attention to visual tokens is insufficient or misallocated, over-focusing on uninformative regions; (2) language prior dominance, where excessive attention to prior response tokens reinforces autoregressive patterns and impairs multimodal alignment; (3) prompt redundancy, where many attention heads fixate on system prompt tokens, disrupting the integration of image, instruction, and response content. To address these issues, we introduce two inference-time interventions: token-level attention intervention (TAI), which enhances focus on salient visual content, and head-level attention intervention (HAI), which suppresses over-attention to prompt and nearby text tokens. VisFlow operates without additional training or model modifications. Extensive experiments across models and benchmarks show that VisFlow effectively reduces hallucinations and improves visual factuality, with negligible computational cost.