Where to Steer: Input-Dependent Layer Selection for Steering Improves LLM Alignment

Soham Gadgil, Chris Lin, Su-In Lee


Abstract
Steering vectors have emerged as a lightweight and effective approach for aligning large language models (LLMs) at inference time, enabling modulation of model behaviors by shifting intermediate representations toward a target behavior. Many existing steering methods apply interventions at globally fixed locations in an LLM, effectively treating the optimal intervention location as input-invariant. However, representations relevant to a target behavior can be encoded at different LLM layers depending on the input. Theoretically, we show that different inputs may require steering at different layers to achieve alignment with a given behavior. Empirically, we observe that the most effective layer for steering varies substantially between inputs. Motivated by these observations, we introduce Where to Steer (W2S), a general framework that adaptively selects intervention layers conditioned on the inputs by learning a mapping from input representations to steering layers. Across multiple LLMs and alignment behaviors, W2S consistently outperforms fixed-layer baselines in both in-distribution and out-of-distribution settings. Our findings suggest that input-dependent layer selection is a key design dimension complementary to methods for steering vector extraction.
Anthology ID:
2026.emnlp-main.1790
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:
40786–40817
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1790/
DOI:
Bibkey:
Cite (ACL):
Soham Gadgil, Chris Lin, and Su-In Lee. 2026. Where to Steer: Input-Dependent Layer Selection for Steering Improves LLM Alignment. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 40786–40817, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Where to Steer: Input-Dependent Layer Selection for Steering Improves LLM Alignment (Gadgil et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1790.pdf