Protecting Privacy Through Approximating Optimal Parameters for Sequence Unlearning in Language Models

Dohyun Lee, Daniel Rim, Minseok Choi, Jaegul Choo


Abstract
Although language models (LMs) demonstrate exceptional capabilities on various tasks, they are potentially vulnerable to extraction attacks, which represent a significant privacy risk.To mitigate the privacy concerns of LMs, machine unlearning has emerged as an important research area, which is utilized to induce the LM to selectively forget about some of its training data.While completely retraining the model will guarantee successful unlearning and privacy assurance, it is impractical for LMs, as it would be time-consuming and resource-intensive.Prior works efficiently unlearn the target token sequences, but upon subsequent iterations, the LM displays significant degradation in performance.In this work, we propose Privacy Protection via Optimal Parameters (POP), a novel unlearning method that effectively forgets the target token sequences from the pretrained LM by applying optimal gradient updates to the parameters.Inspired by the gradient derivation of complete retraining, we approximate the optimal training objective that successfully unlearns the target sequence while retaining the knowledge from the rest of the training data.Experimental results demonstrate that POP exhibits remarkable retention performance post-unlearning across 9 classification and 4 dialogue benchmarks, outperforming the state-of-the-art by a large margin.Furthermore, we introduce Remnant Memorization Accuracy that quantifies privacy risks based on token likelihood and validate its effectiveness through both qualitative and quantitative analyses.
Anthology ID:
2024.findings-acl.936
Volume:
Findings of the Association for Computational Linguistics ACL 2024
Month:
August
Year:
2024
Address:
Bangkok, Thailand and virtual meeting
Editors:
Lun-Wei Ku, Andre Martins, Vivek Srikumar
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
15820–15839
Language:
URL:
https://aclanthology.org/2024.findings-acl.936
DOI:
Bibkey:
Cite (ACL):
Dohyun Lee, Daniel Rim, Minseok Choi, and Jaegul Choo. 2024. Protecting Privacy Through Approximating Optimal Parameters for Sequence Unlearning in Language Models. In Findings of the Association for Computational Linguistics ACL 2024, pages 15820–15839, Bangkok, Thailand and virtual meeting. Association for Computational Linguistics.
Cite (Informal):
Protecting Privacy Through Approximating Optimal Parameters for Sequence Unlearning in Language Models (Lee et al., Findings 2024)
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PDF:
https://aclanthology.org/2024.findings-acl.936.pdf