Lost in Multilinguality: Dissecting Cross-lingual Factual Inconsistency in Transformer Language Models

Fuente: arXiv
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Auteurs principaux: Wang, Mingyang, Adel, Heike, Lange, Lukas, Liu, Yihong, Nie, Ercong, Strötgen, Jannik, Schütze, Hinrich
Format: Preprint
Publié: 2025
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author Wang, Mingyang
Adel, Heike
Lange, Lukas
Liu, Yihong
Nie, Ercong
Strötgen, Jannik
Schütze, Hinrich
author_facet Wang, Mingyang
Adel, Heike
Lange, Lukas
Liu, Yihong
Nie, Ercong
Strötgen, Jannik
Schütze, Hinrich
contents Multilingual language models (MLMs) store factual knowledge across languages but often struggle to provide consistent responses to semantically equivalent prompts in different languages. While previous studies point out this cross-lingual inconsistency issue, the underlying causes remain unexplored. In this work, we use mechanistic interpretability methods to investigate cross-lingual inconsistencies in MLMs. We find that MLMs encode knowledge in a language-independent concept space through most layers, and only transition to language-specific spaces in the final layers. Failures during the language transition often result in incorrect predictions in the target language, even when the answers are correct in other languages. To mitigate this inconsistency issue, we propose a linear shortcut method that bypasses computations in the final layers, enhancing both prediction accuracy and cross-lingual consistency. Our findings shed light on the internal mechanisms of MLMs and provide a lightweight, effective strategy for producing more consistent factual outputs.
format Preprint
id arxiv_https___arxiv_org_abs_2504_04264
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Lost in Multilinguality: Dissecting Cross-lingual Factual Inconsistency in Transformer Language Models
Wang, Mingyang
Adel, Heike
Lange, Lukas
Liu, Yihong
Nie, Ercong
Strötgen, Jannik
Schütze, Hinrich
Computation and Language
Multilingual language models (MLMs) store factual knowledge across languages but often struggle to provide consistent responses to semantically equivalent prompts in different languages. While previous studies point out this cross-lingual inconsistency issue, the underlying causes remain unexplored. In this work, we use mechanistic interpretability methods to investigate cross-lingual inconsistencies in MLMs. We find that MLMs encode knowledge in a language-independent concept space through most layers, and only transition to language-specific spaces in the final layers. Failures during the language transition often result in incorrect predictions in the target language, even when the answers are correct in other languages. To mitigate this inconsistency issue, we propose a linear shortcut method that bypasses computations in the final layers, enhancing both prediction accuracy and cross-lingual consistency. Our findings shed light on the internal mechanisms of MLMs and provide a lightweight, effective strategy for producing more consistent factual outputs.
title Lost in Multilinguality: Dissecting Cross-lingual Factual Inconsistency in Transformer Language Models
topic Computation and Language
url https://arxiv.org/abs/2504.04264