Lost in Literalism: How Supervised Training Shapes Translationese in LLMs

Fuente: arXiv
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Auteurs principaux: Li, Yafu, Zhang, Ronghao, Wang, Zhilin, Zhang, Huajian, Cui, Leyang, Yin, Yongjing, Xiao, Tong, Zhang, Yue
Format: Preprint
Publié: 2025
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author Li, Yafu
Zhang, Ronghao
Wang, Zhilin
Zhang, Huajian
Cui, Leyang
Yin, Yongjing
Xiao, Tong
Zhang, Yue
author_facet Li, Yafu
Zhang, Ronghao
Wang, Zhilin
Zhang, Huajian
Cui, Leyang
Yin, Yongjing
Xiao, Tong
Zhang, Yue
contents Large language models (LLMs) have achieved remarkable success in machine translation, demonstrating impressive performance across diverse languages. However, translationese, characterized by overly literal and unnatural translations, remains a persistent challenge in LLM-based translation systems. Despite their pre-training on vast corpora of natural utterances, LLMs exhibit translationese errors and generate unexpected unnatural translations, stemming from biases introduced during supervised fine-tuning (SFT). In this work, we systematically evaluate the prevalence of translationese in LLM-generated translations and investigate its roots during supervised training. We introduce methods to mitigate these biases, including polishing golden references and filtering unnatural training instances. Empirical evaluations demonstrate that these approaches significantly reduce translationese while improving translation naturalness, validated by human evaluations and automatic metrics. Our findings highlight the need for training-aware adjustments to optimize LLM translation outputs, paving the way for more fluent and target-language-consistent translations. We release the data and code at https://github.com/yafuly/LLM_Translationese.
format Preprint
id arxiv_https___arxiv_org_abs_2503_04369
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Lost in Literalism: How Supervised Training Shapes Translationese in LLMs
Li, Yafu
Zhang, Ronghao
Wang, Zhilin
Zhang, Huajian
Cui, Leyang
Yin, Yongjing
Xiao, Tong
Zhang, Yue
Computation and Language
Large language models (LLMs) have achieved remarkable success in machine translation, demonstrating impressive performance across diverse languages. However, translationese, characterized by overly literal and unnatural translations, remains a persistent challenge in LLM-based translation systems. Despite their pre-training on vast corpora of natural utterances, LLMs exhibit translationese errors and generate unexpected unnatural translations, stemming from biases introduced during supervised fine-tuning (SFT). In this work, we systematically evaluate the prevalence of translationese in LLM-generated translations and investigate its roots during supervised training. We introduce methods to mitigate these biases, including polishing golden references and filtering unnatural training instances. Empirical evaluations demonstrate that these approaches significantly reduce translationese while improving translation naturalness, validated by human evaluations and automatic metrics. Our findings highlight the need for training-aware adjustments to optimize LLM translation outputs, paving the way for more fluent and target-language-consistent translations. We release the data and code at https://github.com/yafuly/LLM_Translationese.
title Lost in Literalism: How Supervised Training Shapes Translationese in LLMs
topic Computation and Language
url https://arxiv.org/abs/2503.04369