Stick to What You Know: A Study of Knowledge-Aligned Supervised Fine-Tuning

Arthur Becker, Jakob Kemmler, David Thulke, Christine Schäfer, Christian Dugast, Hermann Ney


Abstract
Supervised fine-tuning (SFT) trains a base language model to imitate target responses, and these targets may require knowledge the base model has not robustly internalized. We study this as a source of hallucinations and frame a group of mitigation methods as knowledge-aligned SFT: constraining SFT training targets to the base model’s parametric knowledge. Under a unified setup, we compare existing generation-based and estimation-based knowledge-alignment methods and introduce two new variants: Evidence Rewrite, which verifies base-model generations using external evidence, and Recall Rewrite, which retains claims only when they can be consistently recalled by the base model. Experiments with Qwen 3 4B and OLMo 3 7B show that knowledge-aligned SFT can reduce factual hallucinations on WildHalu and Biography while largely preserving general capabilities. Recall Rewrite yields the strongest factuality gains and improves refusal behavior on UnknownBench. It thereby confirms that SFT targets beyond the base model’s knowledge drive hallucination behavior.
Anthology ID:
2026.emnlp-main.523
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:
12063–12099
Language:
URL:
https://aclanthology.org/2026.emnlp-main.523/
DOI:
Bibkey:
Cite (ACL):
Arthur Becker, Jakob Kemmler, David Thulke, Christine Schäfer, Christian Dugast, and Hermann Ney. 2026. Stick to What You Know: A Study of Knowledge-Aligned Supervised Fine-Tuning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 12063–12099, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Stick to What You Know: A Study of Knowledge-Aligned Supervised Fine-Tuning (Becker et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.523.pdf