An Empirical Study of Memorization in NLP

Xiaosen Zheng, Jing Jiang


Abstract
A recent study by Feldman (2020) proposed a long-tail theory to explain the memorization behavior of deep learning models. However, memorization has not been empirically verified in the context of NLP, a gap addressed by this work. In this paper, we use three different NLP tasks to check if the long-tail theory holds. Our experiments demonstrate that top-ranked memorized training instances are likely atypical, and removing the top-memorized training instances leads to a more serious drop in test accuracy compared with removing training instances randomly. Furthermore, we develop an attribution method to better understand why a training instance is memorized. We empirically show that our memorization attribution method is faithful, and share our interesting finding that the top-memorized parts of a training instance tend to be features negatively correlated with the class label.
Anthology ID:
2022.acl-long.434
Volume:
Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
May
Year:
2022
Address:
Dublin, Ireland
Editors:
Smaranda Muresan, Preslav Nakov, Aline Villavicencio
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
6265–6278
Language:
URL:
https://aclanthology.org/2022.acl-long.434
DOI:
10.18653/v1/2022.acl-long.434
Bibkey:
Cite (ACL):
Xiaosen Zheng and Jing Jiang. 2022. An Empirical Study of Memorization in NLP. In Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 6265–6278, Dublin, Ireland. Association for Computational Linguistics.
Cite (Informal):
An Empirical Study of Memorization in NLP (Zheng & Jiang, ACL 2022)
Copy Citation:
PDF:
https://aclanthology.org/2022.acl-long.434.pdf
Code
 xszheng2020/memorization
Data
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