Steering Vector Fields for Context-Aware Inference-Time Control in Large Language Models

Jiaqian Li, Yanshu Li, Kuan-Hao Huang


Abstract
Steering vectors (SVs) offer a lightweight way to control large language models (LLMs) at inference time by shifting hidden activations, providing a practical middle ground between prompting and fine-tuning. Yet SVs can be unreliable in practice. Some concepts are unsteerable, and even when steering helps on average it can backfire for a non-trivial fraction of inputs. Reliability also degrades in long-form generation and multi-attribute steering. We take a geometric view of these failures. A static SV applies the same update vector everywhere in representation space, implicitly assuming that the concept-improving direction is constant across contexts. When the locally effective direction varies with the current activation, a single global vector can become misaligned, which yields weak or reversed effects. Guided by this perspective, we propose Steering Vector Fields (SVF), which learns a differentiable concept scoring function whose local gradient defines the steering direction at each activation, making interventions explicitly context-dependent. This formulation supports coordinated multi-layer interventions in a shared, aligned concept space, and enables efficient long-form and multi-attribute control within a unified framework. Across multiple LLMs and steering tasks, SVF delivers stronger and more reliable control, improving the practicality of inference-time steering. The code is available at https://github.com/lab-flair/SVF.git.
Anthology ID:
2026.emnlp-main.2353
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:
53438–53468
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2353/
DOI:
Bibkey:
Cite (ACL):
Jiaqian Li, Yanshu Li, and Kuan-Hao Huang. 2026. Steering Vector Fields for Context-Aware Inference-Time Control in Large Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 53438–53468, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Steering Vector Fields for Context-Aware Inference-Time Control in Large Language Models (Li et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.2353.pdf