The Geometry of Harmfulness in LLMs through Subconcept Probing

Fuente: arXiv
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Autori principali: Shah, McNair, Angeline, Saleena, Kumar, Adhitya Rajendra, Chheda, Naitik, Zhu, Kevin, Sharma, Vasu, O'Brien, Sean, Cai, Will
Natura: Preprint
Pubblicazione: 2025
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author Shah, McNair
Angeline, Saleena
Kumar, Adhitya Rajendra
Chheda, Naitik
Zhu, Kevin
Sharma, Vasu
O'Brien, Sean
Cai, Will
author_facet Shah, McNair
Angeline, Saleena
Kumar, Adhitya Rajendra
Chheda, Naitik
Zhu, Kevin
Sharma, Vasu
O'Brien, Sean
Cai, Will
contents Recent advances in large language models (LLMs) have intensified the need to understand and reliably curb their harmful behaviours. We introduce a multidimensional framework for probing and steering harmful content in model internals. For each of 55 distinct harmfulness subconcepts (e.g., racial hate, employment scams, weapons), we learn a linear probe, yielding 55 interpretable directions in activation space. Collectively, these directions span a harmfulness subspace that we show is strikingly low-rank. We then test ablation of the entire subspace from model internals, as well as steering and ablation in the subspace's dominant direction. We find that dominant direction steering allows for near elimination of harmfulness with a low decrease in utility. Our findings advance the emerging view that concept subspaces provide a scalable lens on LLM behaviour and offer practical tools for the community to audit and harden future generations of language models.
format Preprint
id arxiv_https___arxiv_org_abs_2507_21141
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Geometry of Harmfulness in LLMs through Subconcept Probing
Shah, McNair
Angeline, Saleena
Kumar, Adhitya Rajendra
Chheda, Naitik
Zhu, Kevin
Sharma, Vasu
O'Brien, Sean
Cai, Will
Artificial Intelligence
Recent advances in large language models (LLMs) have intensified the need to understand and reliably curb their harmful behaviours. We introduce a multidimensional framework for probing and steering harmful content in model internals. For each of 55 distinct harmfulness subconcepts (e.g., racial hate, employment scams, weapons), we learn a linear probe, yielding 55 interpretable directions in activation space. Collectively, these directions span a harmfulness subspace that we show is strikingly low-rank. We then test ablation of the entire subspace from model internals, as well as steering and ablation in the subspace's dominant direction. We find that dominant direction steering allows for near elimination of harmfulness with a low decrease in utility. Our findings advance the emerging view that concept subspaces provide a scalable lens on LLM behaviour and offer practical tools for the community to audit and harden future generations of language models.
title The Geometry of Harmfulness in LLMs through Subconcept Probing
topic Artificial Intelligence
url https://arxiv.org/abs/2507.21141