2025.findings-naacl.32@ACL

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#1 On the Impact of Noise in Differentially Private Text Rewriting [PDF1] [Copy] [Kimi] [REL]

Authors: Stephen Meisenbacher, Maulik Chevli, Florian Matthes

The field of text privatization often leverages the notion of *Differential Privacy* (DP) to provide formal guarantees in the rewriting or obfuscation of sensitive textual data. A common and nearly ubiquitous form of DP application necessitates the addition of calibrated noise to vector representations of text, either at the data- or model-level, which is governed by the privacy parameter πœ€. However, noise addition almost undoubtedly leads to considerable utility loss, thereby highlighting one major drawback of DP in NLP. In this work, we introduce a new sentence infilling privatization technique, and we use this method to explore the effect of noise in DP text rewriting. We empirically demonstrate that non-DP privatization techniques excel in utility preservation and can find an acceptable empirical privacy-utility trade-off, yet cannot outperform DP methods in empirical privacy protections. Our results highlight the significant impact of noise in current DP rewriting mechanisms, leading to a discussion of the merits and challenges of DP in NLP as well as the opportunities that non-DP methods present.

Subject: NAACL.2025 - Findings