发现连续思维模型的隐蔽错误推理,即使输出正确也需警惕。
Ulterior Motives: Detecting Misaligned Reasoning in Continuous Thought Models

- 用隐空间推理替代自然语言,提升效率但难解释。
- 12000个场景测试显示,错误推理藏在潜空间不同区域。
- 早期潜变量就能预警,适合安全监控阶段介入。
链式思维(CoT)是激发大模型复杂推理的关键技术,但依赖自然语言限制了表达能力。连续思维模型通过在隐空间中推理,实现更丰富表征和更快推理,但也带来安全挑战:如何检测不可解释隐空间中的错误推理?为此,我们构建了包含12,000个社会情境的MoralChain基准,采用新型双触发机制训练具后门行为的连续思维模型——一个触发器([T])激活错误潜思,另一个([O])释放有害输出。实验发现:(1) 模型可产生正确输出但存在错误潜思,且对齐与错误潜思占据潜空间中几何上分离的区域;(2) 在行为可区分条件([T][O] vs [O])上训练的线性探测器,能高精度识别已武装但无害状态([T] vs 基线);(3) 错误编码体现在早期潜思标记中,表明安全监控应聚焦潜思的“规划”阶段。
原文摘要 · Abstract (English)
Chain-of-Thought (CoT) reasoning has emerged as a key technique for eliciting complex reasoning in Large Language Models (LLMs). Although interpretable, its dependence on natural language limits the model's expressive bandwidth. Continuous thought models address this bottleneck by reasoning in latent space rather than human-readable tokens. While they enable richer representations and faster inference, they raise a critical safety question: how can we detect misaligned reasoning in an uninterpretable latent space? To study this, we introduce MoralChain, a benchmark of 12,000 social scenarios with parallel moral/immoral reasoning paths. We train a continuous thought model with backdoor behavior using a novel dual-trigger paradigm - one trigger that arms misaligned latent reasoning ([T]) and another that releases harmful outputs ([O]). We demonstrate three findings: (1) continuous thought models can exhibit misaligned latent reasoning while producing aligned outputs, with aligned and misaligned reasoning occupying geometrically distinct regions of latent space; (2) linear probes trained on behaviorally-distinguishable conditions ([T][O] vs [O]) transfer to detecting armed-but-benign states ([T] vs baseline) with high accuracy; and (3) misalignment is encoded in early latent thinking tokens, suggesting safety monitoring for continuous thought models should target the "planning" phase of latent reasoning.
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