Steering Language Models Before They Speak: Logit-Level Interventions

Hyeseon An, Shinwoo Park, Hyundong Jin, Yo-Sub Han


Abstract
Controllable generation requires language models to realize output characteristics such as reading level, politeness, and toxicity. Existing steering methods are often indirect, require access to internal activations, or depend on auxiliary trained models. We propose SWAI, a training-free inference-time method that addresses these limitations by steering directly in logit space using corpus-derived token statistics. SWAI computes z-normalized one-vs-rest log-odds scores from labeled corpora and biases high-scoring tokens only within the model’s top-K candidate set, allowing control to favor target-characteristic tokens while preserving contextually plausible choices. Across readability, politeness, and toxicity control, SWAI consistently improves over prompt-based and prior logit-level baselines without modifying model parameters, accessing internal layers, or training an auxiliary model. Selectivity and lookup-table ablations show that the gains come from target-specific statistical scores rather than generic logit perturbation. These results indicate that effective steering does not require learned controllers when the logit intervention is guided by target-specific statistics under high-probability candidates.
Anthology ID:
2026.emnlp-main.2159
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:
49123–49143
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2159/
DOI:
Bibkey:
Cite (ACL):
Hyeseon An, Shinwoo Park, Hyundong Jin, and Yo-Sub Han. 2026. Steering Language Models Before They Speak: Logit-Level Interventions. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 49123–49143, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Steering Language Models Before They Speak: Logit-Level Interventions (An et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2159.pdf