Has Machine Translation Evaluation Achieved Human Parity? The Human Reference and the Limits of Progress

Lorenzo Proietti, Stefano Perrella, Roberto Navigli


Abstract
In Machine Translation (MT) evaluation, metric performance is assessed based on agreement with human judgments. In recent years, automatic metrics have demonstrated increasingly high levels of agreement with humans. To gain a clearer understanding of metric performance and establish an upper bound, we incorporate human baselines in the MT meta-evaluation, that is, the assessment of MT metrics’ capabilities. Our results show that human annotators are not consistently superior to automatic metrics, with state-of-the-art metrics often ranking on par with or higher than human baselines. Despite these findings suggesting human parity, we discuss several reasons for caution. Finally, we explore the broader implications of our results for the research field, asking: Can we still reliably measure improvements in MT evaluation? With this work, we aim to shed light on the limits of our ability to measure progress in the field, fostering discussion on an issue that we believe is crucial to the entire MT evaluation community.
Anthology ID:
2025.acl-short.63
Volume:
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 2: Short 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:
790–813
Language:
URL:
https://preview.aclanthology.org/landing_page/2025.acl-short.63/
DOI:
Bibkey:
Cite (ACL):
Lorenzo Proietti, Stefano Perrella, and Roberto Navigli. 2025. Has Machine Translation Evaluation Achieved Human Parity? The Human Reference and the Limits of Progress. In Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers), pages 790–813, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
Has Machine Translation Evaluation Achieved Human Parity? The Human Reference and the Limits of Progress (Proietti et al., ACL 2025)
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https://preview.aclanthology.org/landing_page/2025.acl-short.63.pdf