Rethinking Diverse Human Preference Learning through Principal Component
  Analysis
Authors: name: Feng Luo, name: Rui Yang, name: Hao Sun, name: Chunyuan Deng, name: Jiarui Yao, name: Jingyan Shen, name: Huan Zhang, name: Hanjie Chen

Understanding human preferences is crucial for improving foundation models
and building personalized AI systems. However, preferences are inherently
diverse and complex, making it difficult for traditional reward models to
capture their full range. While fine-grained preference data can help,
collecting it is expensive and hard to scale. In this paper, we introduce
Decomposed Reward Models (DRMs), a novel approach that extracts diverse human
preferences from binary comparisons without requiring fine-grained annotations.
Our key insight is to represent human preferences as vectors and analyze them
using Principal Component Analysis (PCA). By constructing a dataset of
embedding differences between preferred and rejected responses, DRMs identify
orthogonal basis vectors that capture distinct aspects of preference. These
decomposed rewards can be flexibly combined to align with different user needs,
offering an interpretable and scalable alternative to traditional reward
models. We demonstrate that DRMs effectively extract meaningful preference
dimensions (e.g., helpfulness, safety, humor) and adapt to new users without
additional training. Our results highlight DRMs as a powerful framework for
personalized and interpretable LLM alignment.