Pulling Out All The Full Stops: Punctuation Sensitivity in Neural Machine Translation and Evaluation

Prathyusha Jwalapuram


Abstract
Much of the work testing machine translation systems for robustness and sensitivity has been adversarial or tended towards testing noisy input such as spelling errors, or non-standard input such as dialects. In this work, we take a step back to investigate a sensitivity problem that can seem trivial and is often overlooked: punctuation. We perform basic sentence-final insertion and deletion perturbation tests with full stops, exclamation and questions marks across source languages and demonstrate a concerning finding: commercial, production-level machine translation systems are vulnerable to mere single punctuation insertion or deletion, resulting in unreliable translations. Moreover, we demonstrate that both string-based and model-based evaluation metrics also suffer from this vulnerability, producing significantly different scores when translations only differ in a single punctuation, with model-based metrics penalizing each punctuation differently. Our work calls into question the reliability of machine translation systems and their evaluation metrics, particularly for real-world use cases, where inconsistent punctuation is often the most common and the least disruptive noise.
Anthology ID:
2023.findings-acl.381
Volume:
Findings of the Association for Computational Linguistics: ACL 2023
Month:
July
Year:
2023
Address:
Toronto, Canada
Editors:
Anna Rogers, Jordan Boyd-Graber, Naoaki Okazaki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
6116–6130
Language:
URL:
https://aclanthology.org/2023.findings-acl.381
DOI:
10.18653/v1/2023.findings-acl.381
Bibkey:
Cite (ACL):
Prathyusha Jwalapuram. 2023. Pulling Out All The Full Stops: Punctuation Sensitivity in Neural Machine Translation and Evaluation. In Findings of the Association for Computational Linguistics: ACL 2023, pages 6116–6130, Toronto, Canada. Association for Computational Linguistics.
Cite (Informal):
Pulling Out All The Full Stops: Punctuation Sensitivity in Neural Machine Translation and Evaluation (Jwalapuram, Findings 2023)
Copy Citation:
PDF:
https://aclanthology.org/2023.findings-acl.381.pdf
Video:
 https://aclanthology.org/2023.findings-acl.381.mp4