SCOPE: Signal-Calibrated On-Policy Distillation Enhancement with Dual-Path Adaptive Weighting

Binbin Zheng, Xing Ma, Yiheng Liang, Jingqing Ruan, Xiaoliang Fu, Kepeng Lin, Benchang Zhu, Ke Zeng, Xunliang Cai


Abstract
On-policy reinforcement learning has become the dominant paradigm for reasoning alignment in large language models, yet its sparse, outcome-level rewards make token-level credit assignment notoriously difficult. On-Policy Distillation (OPD) alleviates this by introducing dense, token-level KL supervision from a teacher model, but typically applies this supervision uniformly across all rollouts, ignoring fundamental differences in signal quality. We propose **S**ignal-**C**alibrated **O**n-**P**olicy Distillation **E**nhancement (**SCOPE**), a dual-path adaptive training framework that routes on-policy rollouts by correctness into two complementary supervision paths. For incorrect trajectories, SCOPE performs teacher-perplexity-weighted KL distillation to prioritize instances where the teacher demonstrates genuine corrective capability, while down-weighting unreliable guidance. For correct trajectories, it applies student-perplexity-weighted Maximum Likelihood Estimation to concentrate reinforcement on low-confidence samples at the capability boundary rather than over-reinforcing already mastered ones. Both paths employ a group-level normalization to adaptively calibrate weight distributions, accounting for the intrinsic difficulty variance across prompts. Extensive experiments on six mathematical reasoning benchmarks show that SCOPE achieves average relative improvements of 11.42% in Avg@32 and 7.30% in Pass@32 over competitive baselines, with extended experiments demonstrating its broader applicability. Code is available at [https://github.com/machine981/SCOPE](https://github.com/machine981/SCOPE).
Anthology ID:
2026.emnlp-main.1131
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
25897–25914
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URL:
https://aclanthology.org/2026.emnlp-main.1131/
DOI:
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Cite (ACL):
Binbin Zheng, Xing Ma, Yiheng Liang, Jingqing Ruan, Xiaoliang Fu, Kepeng Lin, Benchang Zhu, Ke Zeng, and Xunliang Cai. 2026. SCOPE: Signal-Calibrated On-Policy Distillation Enhancement with Dual-Path Adaptive Weighting. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 25897–25914, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SCOPE: Signal-Calibrated On-Policy Distillation Enhancement with Dual-Path Adaptive Weighting (Zheng et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1131.pdf