Want Better Synthetic Data? Steer It: Activation Steering for Low-Resource Language Generation

Jan Cegin, Daniil Gurgurov, Yusser Al Ghussin, Simon Ostermann


Abstract
Large language models (LLMs) have become an effective tool for synthetic data generation, including for low-resource languages, where generated data can improve downstream task performance. Current best-performing approaches typically rely on few-shot prompting with target-language examples, which increases inference costs and may reduce diversity through lexical anchoring. In this work, we investigate activation steering as an alternative for low-resource synthetic data generation. We study two steering strategies: Language Steering, which targets the linguistic identity of a language, and Quality Steering, which captures well-formedness by contrasting human-written and backtranslated text representations. We evaluate these methods across four open-source LLMs, multiple layers, and 11 typologically diverse languages by generating sentiment and topic classification data and fine-tuning smaller classifiers. Steering is applied in both zero-shot and few-shot prompting settings and compared against non-steered counterparts. Our results show that steering on early layers consistently improves the diversity of generated data while often yielding stronger downstream model performance, particularly for low-resource languages.
Anthology ID:
2026.emnlp-main.1290
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:
29385–29412
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1290/
DOI:
Bibkey:
Cite (ACL):
Jan Cegin, Daniil Gurgurov, Yusser Al Ghussin, and Simon Ostermann. 2026. Want Better Synthetic Data? Steer It: Activation Steering for Low-Resource Language Generation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 29385–29412, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Want Better Synthetic Data? Steer It: Activation Steering for Low-Resource Language Generation (Cegin et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1290.pdf