How a Bilingual LM Becomes Bilingual: Tracing Internal Representations with Sparse Autoencoders

Fuente: arXiv
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Autori principali: Inaba, Tatsuro, Kamoda, Go, Inui, Kentaro, Isonuma, Masaru, Miyao, Yusuke, Oseki, Yohei, Heinzerling, Benjamin, Takagi, Yu
Natura: Preprint
Pubblicazione: 2025
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author Inaba, Tatsuro
Kamoda, Go
Inui, Kentaro
Isonuma, Masaru
Miyao, Yusuke
Oseki, Yohei
Heinzerling, Benjamin
Takagi, Yu
author_facet Inaba, Tatsuro
Kamoda, Go
Inui, Kentaro
Isonuma, Masaru
Miyao, Yusuke
Oseki, Yohei
Heinzerling, Benjamin
Takagi, Yu
contents This study explores how bilingual language models develop complex internal representations. We employ sparse autoencoders to analyze internal representations of bilingual language models with a focus on the effects of training steps, layers, and model sizes. Our analysis shows that language models first learn languages separately, and then gradually form bilingual alignments, particularly in the mid layers. We also found that this bilingual tendency is stronger in larger models. Building on these findings, we demonstrate the critical role of bilingual representations in model performance by employing a novel method that integrates decomposed representations from a fully trained model into a mid-training model. Our results provide insights into how language models acquire bilingual capabilities.
format Preprint
id arxiv_https___arxiv_org_abs_2503_06394
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle How a Bilingual LM Becomes Bilingual: Tracing Internal Representations with Sparse Autoencoders
Inaba, Tatsuro
Kamoda, Go
Inui, Kentaro
Isonuma, Masaru
Miyao, Yusuke
Oseki, Yohei
Heinzerling, Benjamin
Takagi, Yu
Computation and Language
Machine Learning
This study explores how bilingual language models develop complex internal representations. We employ sparse autoencoders to analyze internal representations of bilingual language models with a focus on the effects of training steps, layers, and model sizes. Our analysis shows that language models first learn languages separately, and then gradually form bilingual alignments, particularly in the mid layers. We also found that this bilingual tendency is stronger in larger models. Building on these findings, we demonstrate the critical role of bilingual representations in model performance by employing a novel method that integrates decomposed representations from a fully trained model into a mid-training model. Our results provide insights into how language models acquire bilingual capabilities.
title How a Bilingual LM Becomes Bilingual: Tracing Internal Representations with Sparse Autoencoders
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2503.06394