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Autori principali: Braun, Joschka, Eickhoff, Carsten, Krueger, David, Bahrainian, Seyed Ali, Krasheninnikov, Dmitrii
Natura: Preprint
Pubblicazione: 2025
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Accesso online:https://arxiv.org/abs/2505.22637
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author Braun, Joschka
Eickhoff, Carsten
Krueger, David
Bahrainian, Seyed Ali
Krasheninnikov, Dmitrii
author_facet Braun, Joschka
Eickhoff, Carsten
Krueger, David
Bahrainian, Seyed Ali
Krasheninnikov, Dmitrii
contents Steering vectors are a lightweight method to control language model behavior by adding a learned bias to the activations at inference time. Although steering demonstrates promising performance, recent work shows that it can be unreliable or even counterproductive in some cases. This paper studies the influence of prompt types and the geometry of activation differences on steering reliability. First, we find that all seven prompt types used in our experiments produce a net positive steering effect, but exhibit high variance across samples, and often give an effect opposite of the desired one. No prompt type clearly outperforms the others, and yet the steering vectors resulting from the different prompt types often differ directionally (as measured by cosine similarity). Second, we show that higher cosine similarity between training set activation differences predicts more effective steering. Finally, we observe that datasets where positive and negative activations are better separated are more steerable. Our results suggest that vector steering is unreliable when the target behavior is not represented by a coherent direction.
format Preprint
id arxiv_https___arxiv_org_abs_2505_22637
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Understanding (Un)Reliability of Steering Vectors in Language Models
Braun, Joschka
Eickhoff, Carsten
Krueger, David
Bahrainian, Seyed Ali
Krasheninnikov, Dmitrii
Machine Learning
Steering vectors are a lightweight method to control language model behavior by adding a learned bias to the activations at inference time. Although steering demonstrates promising performance, recent work shows that it can be unreliable or even counterproductive in some cases. This paper studies the influence of prompt types and the geometry of activation differences on steering reliability. First, we find that all seven prompt types used in our experiments produce a net positive steering effect, but exhibit high variance across samples, and often give an effect opposite of the desired one. No prompt type clearly outperforms the others, and yet the steering vectors resulting from the different prompt types often differ directionally (as measured by cosine similarity). Second, we show that higher cosine similarity between training set activation differences predicts more effective steering. Finally, we observe that datasets where positive and negative activations are better separated are more steerable. Our results suggest that vector steering is unreliable when the target behavior is not represented by a coherent direction.
title Understanding (Un)Reliability of Steering Vectors in Language Models
topic Machine Learning
url https://arxiv.org/abs/2505.22637