PAWS: Preference Learning with Advantage-Weighted Segments

Abstract:Preference-based reinforcement learning (PbRL) learns policies from human trajectory-level comparisons, avoiding explicit reward design and expert demonstrations. Existing methods typically train utility functions on trajectory or segment-level preferences while relying on per-step utility estimates during policy optimization. This training and inference mismatch induces a distribution shift that severely degrades temporal credit assignment and limits policy learning. We analyze this issue and propose PAWS, a segment-based preference learning method that performs policy updates directly using segment-level advantage functions. By aligning utility training with policy optimization, PAWS preserves trajectory-level preference information and avoids unreliable per-step learning signals. Experiments on simulated robotic manipulation and locomotion tasks demonstrate that PAWS consistently outperforms existing PbRL approaches, highlighting the importance of distribution-consistent preference learning.

Machine Learning (cs.LG)

arXiv:2606.11982 [cs.LG]

(or arXiv:2606.11982v1 [cs.LG] for this version)

https://doi.org/10.48550/arXiv.2606.11982 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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