Risk-aware Selective Prompting for Hallucination Mitigation in Large Vision-Language Models
- URL: http://arxiv.org/abs/2605.28123v1
- Date: Wed, 27 May 2026 08:14:59 GMT
- Title: Risk-aware Selective Prompting for Hallucination Mitigation in Large Vision-Language Models
- Abstract summary: We study verification prompting in large vision-language models (LVLMs)<n>We find that it is a risk-bearing intervention: its corrections increase with input difficulty, while newly introduced errors persist across difficulty levels.<n>We propose Risk-aware Selective Prompting (RSP), a training-free approach that uses pre-generation uncertainty signals to trigger verification selectively.
- Score: 0.6925738064847174
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Prompt-based verification is widely used to mitigate hallucinations in large vision-language models (LVLMs), yet when it helps remains poorly understood. We systematically study verification prompting across two representative LVLM architectures and hallucination benchmarks, and find that it is a risk-bearing intervention: its corrections increase with input difficulty, while newly introduced errors persist across difficulty levels. As a result, always-on prompting helps on hard inputs but offers little benefit -- and can harm -- easier ones. Our analysis further shows that this behavior is associated with a conservative output shift. Verification prompts redistribute attention from visual tokens toward instruction tokens and induce a distinct middle-layer entropy pattern absent in a neutral-prompt control, suggesting instruction-conditioned attention redistribution rather than uniformly improved visual grounding. Motivated by this input-dependent risk, we propose Risk-aware Selective Prompting (RSP), a training-free approach that uses pre-generation uncertainty signals to trigger verification selectively. RSP mitigates the degradation of always-on prompting while preserving baseline performance, and reveals that effective selection signals vary across architectures.
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