Decomposing Representation Space into Interpretable Subspaces with Unsupervised Learning

Fuente: arXiv
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Auteurs principaux: Huang, Xinting, Hahn, Michael
Format: Preprint
Publié: 2025
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author Huang, Xinting
Hahn, Michael
author_facet Huang, Xinting
Hahn, Michael
contents Understanding internal representations of neural models is a core interest of mechanistic interpretability. Due to its large dimensionality, the representation space can encode various aspects about inputs. To what extent are different aspects organized and encoded in separate subspaces? Is it possible to find these ``natural'' subspaces in a purely unsupervised way? Somewhat surprisingly, we can indeed achieve this and find interpretable subspaces by a seemingly unrelated training objective. Our method, neighbor distance minimization (NDM), learns non-basis-aligned subspaces in an unsupervised manner. Qualitative analysis shows subspaces are interpretable in many cases, and encoded information in obtained subspaces tends to share the same abstract concept across different inputs, making such subspaces similar to ``variables'' used by the model. We also conduct quantitative experiments using known circuits in GPT-2; results show a strong connection between subspaces and circuit variables. We also provide evidence showing scalability to 2B models by finding separate subspaces mediating context and parametric knowledge routing. Viewed more broadly, our findings offer a new perspective on understanding model internals and building circuits.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01916
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Decomposing Representation Space into Interpretable Subspaces with Unsupervised Learning
Huang, Xinting
Hahn, Michael
Machine Learning
Artificial Intelligence
Computation and Language
Understanding internal representations of neural models is a core interest of mechanistic interpretability. Due to its large dimensionality, the representation space can encode various aspects about inputs. To what extent are different aspects organized and encoded in separate subspaces? Is it possible to find these ``natural'' subspaces in a purely unsupervised way? Somewhat surprisingly, we can indeed achieve this and find interpretable subspaces by a seemingly unrelated training objective. Our method, neighbor distance minimization (NDM), learns non-basis-aligned subspaces in an unsupervised manner. Qualitative analysis shows subspaces are interpretable in many cases, and encoded information in obtained subspaces tends to share the same abstract concept across different inputs, making such subspaces similar to ``variables'' used by the model. We also conduct quantitative experiments using known circuits in GPT-2; results show a strong connection between subspaces and circuit variables. We also provide evidence showing scalability to 2B models by finding separate subspaces mediating context and parametric knowledge routing. Viewed more broadly, our findings offer a new perspective on understanding model internals and building circuits.
title Decomposing Representation Space into Interpretable Subspaces with Unsupervised Learning
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2508.01916