Train Smarter, Not Harder: Switching Signal-Guided Training in Active Learning

Nagham Omar, Maya Rozenshtein, Evgeny Mishlyakov, Avigdor Gal


Abstract
Training strategy, namely whether to retrain from scratch or fine-tune from the previous checkpoint, is an overlooked decision variable in active learning. We show that this choice has exploitable structure: retraining is most useful in early rounds, when each batch can substantially reshape the labeled distribution, while fine-tuning becomes safer once the model trajectory stabilizes. We propose HybridAL, an adaptive training schedule that monitors an online stabilization signal and switches from retraining to fine-tuning after sustained stabilization. Two complementary signals, spectral exponent change 𝛥𝛼 (weight-based) and accuracy change 𝛥Acc (validation-based), span different points on the time-calibration trade-off. Across three encoder backbones and six text-classification tasks (five seeds each), HybridAL keeps endpoint macro-F1 non-inferior to retraining and fine-tuning at a 0.010 margin, saves up to 49% of retraining time, and recovers a substantial fraction of retraining’s calibration advantage as measured by negative log-likelihood (NLL). Compared with schedules that switch at a pre-committed round, HybridAL obtains lower NLL at moderate additional cost, showing that trajectory-dependent switching provides a stronger time-calibration trade-off than fixed early switching.
Anthology ID:
2026.emnlp-main.237
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
Note:
Pages:
5423–5445
Language:
URL:
https://aclanthology.org/2026.emnlp-main.237/
DOI:
Bibkey:
Cite (ACL):
Nagham Omar, Maya Rozenshtein, Evgeny Mishlyakov, and Avigdor Gal. 2026. Train Smarter, Not Harder: Switching Signal-Guided Training in Active Learning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 5423–5445, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Train Smarter, Not Harder: Switching Signal-Guided Training in Active Learning (Omar et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.237.pdf