Causal Interventions on Continuous Variables: A Case Study on Verb Bias in Steering Vectors for In-Context Learning

Zhenghao Herbert Zhou, R. Thomas McCoy, Robert Frank


Abstract
Causal interventions in language model representations have largely targeted discrete features, like grammatical number. However, language models must also make use of features that are graded. We introduce a method for causal intervention on continuous variables: given activation vectors paired with a graded target variable, we localize a low-dimensional direction for that variable and use this direction to edit vectors toward counterfactual target values. We apply this method to a continuous feature that is well-studied in psycholinguistics, namely verb bias (which reflects which syntactic structures tend to follow a given verb). We show that verb bias is causally represented in steering vectors extracted from large language models: counterfactual edits to verb bias systematically shift downstream structural preferences. Verb bias has also previously been linked to in-context learning; in further analyses, we find that steering vectors in our experiments encode error signals that could drive the error-driven update behavior seen in in-context learning but that these aspects of the steering vectors are not causally used in downstream production. Overall, these results show causal interventions can be applied to continuous variables, though connecting continuous variables to in-context learning remains a challenge.
Anthology ID:
2026.emnlp-main.989
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
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
22788–22805
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URL:
https://aclanthology.org/2026.emnlp-main.989/
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Cite (ACL):
Zhenghao Herbert Zhou, R. Thomas McCoy, and Robert Frank. 2026. Causal Interventions on Continuous Variables: A Case Study on Verb Bias in Steering Vectors for In-Context Learning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 22788–22805, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Causal Interventions on Continuous Variables: A Case Study on Verb Bias in Steering Vectors for In-Context Learning (Zhou et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.989.pdf