Are Synonym Substitution Attacks Really Synonym Substitution Attacks?

Cheng-Han Chiang, Hung-yi Lee


Abstract
In this paper, we explore the following question: Are synonym substitution attacks really synonym substitution attacks (SSAs)?We approach this question by examining how SSAs replace words in the original sentence and show that there are still unresolved obstacles that make current SSAs generate invalid adversarial samples. We reveal that four widely used word substitution methods generate a large fraction of invalid substitution words that are ungrammatical or do not preserve the original sentence’s semantics. Next, we show that the semantic and grammatical constraints used in SSAs for detecting invalid word replacements are highly insufficient in detecting invalid adversarial samples.
Anthology ID:
2023.findings-acl.117
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:
1853–1878
Language:
URL:
https://aclanthology.org/2023.findings-acl.117
DOI:
10.18653/v1/2023.findings-acl.117
Bibkey:
Cite (ACL):
Cheng-Han Chiang and Hung-yi Lee. 2023. Are Synonym Substitution Attacks Really Synonym Substitution Attacks?. In Findings of the Association for Computational Linguistics: ACL 2023, pages 1853–1878, Toronto, Canada. Association for Computational Linguistics.
Cite (Informal):
Are Synonym Substitution Attacks Really Synonym Substitution Attacks? (Chiang & Lee, Findings 2023)
Copy Citation:
PDF:
https://preview.aclanthology.org/dois-2013-emnlp/2023.findings-acl.117.pdf
Video:
 https://preview.aclanthology.org/dois-2013-emnlp/2023.findings-acl.117.mp4