Multi-perspective Alignment for Increasing Naturalness in Neural Machine Translation

Huiyuan Lai, Esther Ploeger, Rik Van Noord, Antonio Toral


Abstract
Neural machine translation (NMT) systems amplify lexical biases present in their training data, leading to artificially impoverished language in output translations. These language-level characteristics render automatic translations different from text originally written in a language and human translations, which hinders their usefulness in for example creating evaluation datasets. Attempts to increase naturalness in NMT can fall short in terms of content preservation, where increased lexical diversity comes at the cost of translation accuracy. Inspired by the reinforcement learning from human feedback framework, we introduce a novel method that rewards both naturalness and content preservation. We experiment with multiple perspectives to produce more natural translations, aiming at reducing machine and human translationese. We evaluate our method on English-to-Dutch literary translation, and find that our best model produces translations that are lexically richer and exhibit more properties of human-written language, without loss in translation accuracy.
Anthology ID:
2025.acl-long.1361
Volume:
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Wanxiang Che, Joyce Nabende, Ekaterina Shutova, Mohammad Taher Pilehvar
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
28071–28084
Language:
URL:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.1361/
DOI:
Bibkey:
Cite (ACL):
Huiyuan Lai, Esther Ploeger, Rik Van Noord, and Antonio Toral. 2025. Multi-perspective Alignment for Increasing Naturalness in Neural Machine Translation. In Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 28071–28084, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
Multi-perspective Alignment for Increasing Naturalness in Neural Machine Translation (Lai et al., ACL 2025)
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PDF:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.1361.pdf