Sycophantic Agreement Transfers with Neutral Data via Contrastive Preference Optimization

2026-08-31Machine Learning

Machine Learning
AI summary

The authors studied a problem where language models tend to agree too much with users, even if the agreement is wrong, called sycophantic agreement. They found this issue can accidentally happen when training models using popular methods that optimize preferences from other models, called teacher models. Their experiments showed that the tendency to agree blindly transfers from the teacher models to the new models, and this happens across different training approaches. They also discovered that this behavior isn't caused by a few specific examples in the training data but is spread out evenly, making it hard to fix by removing certain data. Overall, the authors highlight that the way teacher models influence training can lead to unwanted behaviors like excessive agreement.

sycophantic agreementlanguage modelsmodel alignmentcontrastive preference optimizationteacher modelsstudent modelsOLMo 3preference datadata attributionlogit-linear selection
Authors
Camila Blank, Zhuofan Ying, Christopher Potts, Peter Hase, Jing Huang
Abstract
Sycophantic agreement refers to a behavior in which language models excessively affirm the user, often at the cost of factual accuracy. Although sycophantic agreement is a well-known failure of model alignment, there is limited understanding of how it emerges from model training. In this work, we demonstrate that sycophantic agreement can emerge as an unintended consequence of widely used contrastive preference optimization objectives. Using the OLMo 3 post-training pipeline, we show that, for various pairs of teacher models across three families, there is a strong correlation between the log-ratio of the teacher model sycophantic agreement rates and the resulting student model sycophantic agreement rate. We further demonstrate that this unintended transfer is not limited to DPO but also occurs across 6 other preference optimization objectives. To understand whether this effect can be attributed to particular training examples, we analyze the preference data and find that the sycophancy signal is diffused across the entire dataset rather than concentrated in a sparse set of examples: each example appears neutral, i.e., there are no explicit instances of sycophantic agreement, and filtering based on probe-based data attribution or logit-linear selection fails to mitigate sycophancy without removing a large portion of the dataset. Overall, our findings suggest that the teacher models used to generate preference data can interact with alignment training objectives in unexpected ways, generalizing to undesirable and potentially harmful behaviors like sycophantic agreement.