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arXiv 2607.01802cs.CL
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关于偏好对齐生成的引导向量限制研究

On the Limits of Steering Vectors for Preference-Aligned Generation

Department of Computer Science, Columbia University(哥伦比亚大学计算机科学系)

Melanie Subbiah, Zara Hall, Kathleen McKeown

AI总结:

研究引导向量在偏好对齐生成中的泛化限制,发现其有效性在不同特质、任务迁移和多特质组合中显著下降,表明其作为通用工具的局限性。

摘要:

引导向量已成为一种有前景的受控文本生成方法,提供了可解释、无需训练的形状模型输出机制。然而,其实际通用性仍知之甚少。我们沿三个维度研究引导向量泛化的限制:特质可表达性、任务迁移和多特质组合。使用PLUME写作个性化基准,我们提取了一系列偏好的引导向量,并在两个开源模型(Qwen2.5-7B-Instruct和Llama3.1-8B-Instruct)上评估它们在摘要和电子邮件写作任务中的表现。我们发现引导有效性在不同特质间差异显著。我们进一步表明,当从正面和负面风格示例中提取的向量被迁移到下游写作个性化任务时,引导有效性可能下降。最后,我们比较了组合多个引导向量的常见方法,发现随着添加更多向量,所有方法在特质表达上均显著下降,并在连贯性和可表达性之间存在权衡,需要针对每个设置进行超参数调优。综合来看,我们的结果表明,引导向量作为偏好对齐的通用工具面临有意义的限制。

英文摘要:

Steering vectors have emerged as a promising approach to controlled text generation, offering interpretable, training-free mechanisms for shaping model outputs. However, their practical generality remains poorly understood. We study the limits of steering vector generalization along three dimensions: trait expressibility, task transfer, and multi-trait composition. Using the PLUME writing personalization benchmark, we extract steering vectors for a range of preferences and evaluate them on summarization and email-writing tasks across two open-source models (Qwen2.5-7B-Instruct and Llama3.1-8B-Instruct). We find that steering effectiveness varies substantially across traits. We further show that steering effectiveness can degrade when vectors extracted from positive and negative style examples are transferred to downstream writing personalization tasks. Finally, we compare common methods for composing multiple steering vectors and find that all methods suffer significant drops in trait expression as more vectors are added, with a tradeoff between coherence and expressibility that requires per-setting hyperparameter tuning. Taken together, our results suggest that steering vectors face meaningful limits as a general-purpose tool for preference alignment.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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