Understanding Reasoning in Thinking Language Models via Steering Vectors

Fuente: arXiv
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Main Authors: Venhoff, Constantin, Arcuschin, Iván, Torr, Philip, Conmy, Arthur, Nanda, Neel
Format: Preprint
Published: 2025
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_version_ 1866912663453302784
author Venhoff, Constantin
Arcuschin, Iván
Torr, Philip
Conmy, Arthur
Nanda, Neel
author_facet Venhoff, Constantin
Arcuschin, Iván
Torr, Philip
Conmy, Arthur
Nanda, Neel
contents Recent advances in large language models (LLMs) have led to the development of thinking language models that generate extensive internal reasoning chains before producing responses. While these models achieve improved performance, controlling their reasoning processes remains challenging. This work presents a steering approach for thinking LLMs by analyzing and manipulating specific reasoning behaviors in DeepSeek-R1-Distill models. Through a systematic experiment on 500 tasks across 10 diverse categories, we identify several reasoning behaviors exhibited by thinking models, including expressing uncertainty, generating examples for hypothesis validation, and backtracking in reasoning chains. We demonstrate that these behaviors are mediated by linear directions in the model's activation space and can be controlled using steering vectors. By extracting and applying these vectors, we provide a method to modulate specific aspects of the model's reasoning process, such as its tendency to backtrack or express uncertainty. Our approach offers practical tools for steering reasoning processes in thinking models in a controlled and interpretable manner. We validate our steering method using three DeepSeek-R1-Distill models, demonstrating consistent control across different model architectures.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18167
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Understanding Reasoning in Thinking Language Models via Steering Vectors
Venhoff, Constantin
Arcuschin, Iván
Torr, Philip
Conmy, Arthur
Nanda, Neel
Machine Learning
Artificial Intelligence
Recent advances in large language models (LLMs) have led to the development of thinking language models that generate extensive internal reasoning chains before producing responses. While these models achieve improved performance, controlling their reasoning processes remains challenging. This work presents a steering approach for thinking LLMs by analyzing and manipulating specific reasoning behaviors in DeepSeek-R1-Distill models. Through a systematic experiment on 500 tasks across 10 diverse categories, we identify several reasoning behaviors exhibited by thinking models, including expressing uncertainty, generating examples for hypothesis validation, and backtracking in reasoning chains. We demonstrate that these behaviors are mediated by linear directions in the model's activation space and can be controlled using steering vectors. By extracting and applying these vectors, we provide a method to modulate specific aspects of the model's reasoning process, such as its tendency to backtrack or express uncertainty. Our approach offers practical tools for steering reasoning processes in thinking models in a controlled and interpretable manner. We validate our steering method using three DeepSeek-R1-Distill models, demonstrating consistent control across different model architectures.
title Understanding Reasoning in Thinking Language Models via Steering Vectors
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2506.18167