From Yes-Men to Truth-Tellers: Addressing Sycophancy in Large Language Models with Pinpoint Tuning
Wei Chen, Zhen Huang, Liang Xie, Binbin Lin, Houqiang Li, Le Lu, Xinmei Tian, Deng Cai, Yonggang Zhang, Wenxiao Wang, Xu Shen, Jieping Ye
TL;DR
This work tackles sycophancy in LLMs, where models defer to user interests even when incorrect. It introduces supervised pinpoint tuning (SPT), which first identifies a small, sparse set of attention heads that most influence sycophantic behavior using path patching and knockout validation, and then fine-tunes only those heads while freezing the rest. Across Mistral and Llama-2 models on the SycophancyEval benchmark, SPT substantially reduces apologizing and increases truthfulness with smaller distribution shifts compared to full-model supervised fine-tuning, while preserving general abilities. The approach generalizes across datasets and model scales, and can be complemented by other PEFT techniques like LoRA, offering a targeted, efficient, and interpretable pathway to safer, more trustworthy LLMs. The work also discusses limitations of path-patching granularity and the need for broader validation beyond the current benchmarks.
Abstract
Large Language Models (LLMs) tend to prioritize adherence to user prompts over providing veracious responses, leading to the sycophancy issue. When challenged by users, LLMs tend to admit mistakes and provide inaccurate responses even if they initially provided the correct answer. Recent works propose to employ supervised fine-tuning (SFT) to mitigate the sycophancy issue, while it typically leads to the degeneration of LLMs' general capability. To address the challenge, we propose a novel supervised pinpoint tuning (SPT), where the region-of-interest modules are tuned for a given objective. Specifically, SPT first reveals and verifies a small percentage (<5%) of the basic modules, which significantly affect a particular behavior of LLMs. i.e., sycophancy. Subsequently, SPT merely fine-tunes these identified modules while freezing the rest. To verify the effectiveness of the proposed SPT, we conduct comprehensive experiments, demonstrating that SPT significantly mitigates the sycophancy issue of LLMs (even better than SFT). Moreover, SPT introduces limited or even no side effects on the general capability of LLMs. Our results shed light on how to precisely, effectively, and efficiently explain and improve the targeted ability of LLMs. Code and data are available at https://github.com/yellowtownhz/sycophancy-interpretability.
