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Main Authors: Deng, Boyi, Wan, Yu, Zhang, Yidan, Yang, Baosong, Feng, Fuli
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2505.05111
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author Deng, Boyi
Wan, Yu
Zhang, Yidan
Yang, Baosong
Feng, Fuli
author_facet Deng, Boyi
Wan, Yu
Zhang, Yidan
Yang, Baosong
Feng, Fuli
contents The mechanisms behind multilingual capabilities in Large Language Models (LLMs) have been examined using neuron-based or internal-activation-based methods. However, these methods often face challenges such as superposition and layer-wise activation variance, which limit their reliability. Sparse Autoencoders (SAEs) offer a more nuanced analysis by decomposing the activations of LLMs into a sparse linear combination of SAE features. We introduce a novel metric to assess the monolinguality of features obtained from SAEs, discovering that some features are strongly related to specific languages. Additionally, we show that ablating these SAE features only significantly reduces abilities in one language of LLMs, leaving others almost unaffected. Interestingly, we find some languages have multiple synergistic SAE features, and ablating them together yields greater improvement than ablating individually. Moreover, we leverage these SAE-derived language-specific features to enhance steering vectors, achieving control over the language generated by LLMs. The code is publicly available at https://github.com/Aatrox103/multilingual-llm-features.
format Preprint
id arxiv_https___arxiv_org_abs_2505_05111
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unveiling Language-Specific Features in Large Language Models via Sparse Autoencoders
Deng, Boyi
Wan, Yu
Zhang, Yidan
Yang, Baosong
Feng, Fuli
Computation and Language
The mechanisms behind multilingual capabilities in Large Language Models (LLMs) have been examined using neuron-based or internal-activation-based methods. However, these methods often face challenges such as superposition and layer-wise activation variance, which limit their reliability. Sparse Autoencoders (SAEs) offer a more nuanced analysis by decomposing the activations of LLMs into a sparse linear combination of SAE features. We introduce a novel metric to assess the monolinguality of features obtained from SAEs, discovering that some features are strongly related to specific languages. Additionally, we show that ablating these SAE features only significantly reduces abilities in one language of LLMs, leaving others almost unaffected. Interestingly, we find some languages have multiple synergistic SAE features, and ablating them together yields greater improvement than ablating individually. Moreover, we leverage these SAE-derived language-specific features to enhance steering vectors, achieving control over the language generated by LLMs. The code is publicly available at https://github.com/Aatrox103/multilingual-llm-features.
title Unveiling Language-Specific Features in Large Language Models via Sparse Autoencoders
topic Computation and Language
url https://arxiv.org/abs/2505.05111