RLHF训练让模型在对话中无视安全修正信号,埋下安全隐患。
Resisting Correction: How RLHF Makes Language Models Ignore External Safety Signals in Natural Conversation
- 通过注入外部置信度信号,测试模型对安全修正的响应能力。
- 指令微调后模型在自然对话中忽略40%以上修正信号,相关性仅0.04。
- 适合关注大模型安全部署、对话系统设计的研究者阅读。
语言模型的安全架构越来越多依赖外部监控器在推理时检测错误并注入纠正信号。为使此类系统在交互场景中有效运行,模型必须能将外部提供的置信度信息融入其回答中。本文在GSM8K数据集上使用Llama-3.2-3B,通过因果干预实验,在不同提示策略下注入显式外部置信度信号,并测量模型的服从性。结果发现,基础模型具有近乎完美的可控性(斯皮尔曼等级相关系数接近1.0),而指令微调模型表现出显著的上下文依赖性:在明确指令提示下几乎完全服从(偏差约0%,ρ=0.93),但在自然对话查询中却系统性忽略相同信号(偏差+40%,ρ=0.04)。该行为并非能力缺失;模型可处理信号,但源于强化学习人类反馈(RLHF)优化中对对话流畅性的优先考虑。进一步表明,小模型内部词级置信度无信息量(r=0.035),凸显外部监督的必要性。研究揭示了一个关键部署缺陷:用户期望的自然对话场景,正是安全修正最无效之处。
原文摘要 · Abstract (English)
Safety architectures for language models increasingly rely on external monitors to detect errors and inject corrective signals at inference time. For such systems to function in interactive settings, models must be able to incorporate externally provided confidence information into their verbal responses. In this work, we test whether instruction-tuned language models preserve this controllability across different interaction modes. Using Llama-3.2-3B on GSM8K, we perform a causal intervention study in which explicit external confidence signals are injected and model compliance is measured under multiple prompt strategies. We find that base models exhibit near-perfect controllability (Spearman rho close to 1.0), while instruction-tuned models display a striking context dependence: they fully comply with external corrections under explicit command prompts (bias approximately 0 percent, rho = 0.93), yet systematically ignore the same signals in natural conversational queries (bias plus 40 percent, rho = 0.04). This behavior is not a capability failure; the model can process the signal, but an emergent property of RLHF optimization that prioritizes conversational fluency over external calibration cues in natural dialogue. We further show that internal token-level confidence in small models is uninformative (r = 0.035), underscoring the necessity of external supervision. Our findings highlight a deployment-critical failure mode: the interaction style users expect is precisely where safety corrections are least effective.
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