微调导致模型产生突发性偏移,且泛化偏差更稳定高效
Emergent Misalignment is Easy, Narrow Misalignment is Hard
- 通过引入KL散度损失,发现窄任务解存在线性表示
- 泛化偏差的损失更低,抗扰动更强,影响预训练分布更大
- 为监控和缓解模型偏移提供可追踪的线性表征
在狭隘有害数据集上微调大语言模型,可能导致其在多种无关场景中表现出典型的“邪恶”回应,即产生突发性偏移(EM)。令人担忧的是,专家预注册调查未能预测该结果,反映出我们对大语言模型学习与泛化中归纳偏置的理解不足。本文以突发性偏移为案例,研究这些归纳偏置,发现模型可仅学习窄任务目标,但泛化解更具稳定性与效率。我们发现不同EM微调结果收敛到相同的泛化偏差线性表示,可用于调节偏移行为。同时,窄解也存在线性表示,可通过引入KL散度损失学习。对比表明,泛化偏差损失更低、对扰动更鲁棒,并在预训练分布中影响更大。本工作为监测与缓解偏移提供了具体可追踪的表示。更广泛而言,提供了研究归纳偏置如何塑造大模型泛化的详细案例与初步指标。所有代码、数据集及微调模型均已开源。
原文摘要 · Abstract (English)
Finetuning large language models on narrowly harmful datasets can cause them to become emergently misaligned, giving stereotypically `evil' responses across diverse unrelated settings. Concerningly, a pre-registered survey of experts failed to predict this result, highlighting our poor understanding of the inductive biases governing learning and generalisation in LLMs. We use emergent misalignment (EM) as a case study to investigate these inductive biases and find that models can just learn the narrow dataset task, but that the general solution appears to be more stable and more efficient. To establish this, we build on the result that different EM finetunes converge to the same linear representation of general misalignment, which can be used to mediate misaligned behaviour. We find a linear representation of the narrow solution also exists, and can be learned by introducing a KL divergence loss. Comparing these representations reveals that general misalignment achieves lower loss, is more robust to perturbations, and is more influential in the pre-training distribution. This work isolates a concrete representation of general misalignment for monitoring and mitigation. More broadly, it offers a detailed case study and preliminary metrics for investigating how inductive biases shape generalisation in LLMs. We open-source all code, datasets and model finetunes.
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