Contrastive ESA: Human Evaluation of Multiple Translations at Once

Vilem Zouhar, Roman Grundkiewicz, Sara Rajaee, Parker Riley, Rachel Bawden, Philipp Koehn, Marine Carpuat, Tom Kocmi


Abstract
Current human evaluation of machine translation typically assesses single outputs in isolation, a paradigm that suffers from high annotator noise and cost. We introduce Contrastive Error Span Annotation (cESA), a protocol that presents multiple translations of the source input (text, video, audio, image). In cESA, the annotator sees multiple translations of the same document, marks major and minor error spans, and then assigns a score from 0% to 100% on absolute scale. By allowing annotators to access the shared context across multiple outputs, cESA facilitates more consistent and efficient judgments. We validate cESA using a large-scale human evaluation of English-Japanese translations of 12 models, demonstrating reductions in annotation time and noise compared to standard pointwise evaluation. Unlike existing contrastive ranking methods, cESA yields absolute quality judgments that enable simple, interpretable non-parametric model rankings without the need for post-hoc corrections.
Anthology ID:
2026.wmt-main.47
Volume:
Proceedings of the Eleventh Conference on Machine Translation
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
Venues:
WMT | WS
SIG:
SIGMT
Publisher:
Association for Computational Linguistics
Note:
Pages:
860–872
Language:
URL:
https://aclanthology.org/2026.wmt-main.47/
DOI:
Bibkey:
Cite (ACL):
Vilem Zouhar, Roman Grundkiewicz, Sara Rajaee, Parker Riley, Rachel Bawden, Philipp Koehn, Marine Carpuat, and Tom Kocmi. 2026. Contrastive ESA: Human Evaluation of Multiple Translations at Once. In Proceedings of the Eleventh Conference on Machine Translation, pages 860–872, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Contrastive ESA: Human Evaluation of Multiple Translations at Once (Zouhar et al., WMT 2026)
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PDF:
https://aclanthology.org/2026.wmt-main.47.pdf