Differentially-Private Text Rewriting reshapes Linguistic Style

TL;DR

This paper investigates how differential privacy applied to text rewriting affects linguistic style, revealing that privacy-preserving methods significantly alter stylistic and functional aspects of language.

Contribution

It provides a multidimensional analysis of stylistic changes caused by differentially-private text rewriting, highlighting the loss of interactive and contextual markers.

Findings

Privacy-preserving rewriting reduces stylistic diversity.

Both autoregressive and bidirectional methods converge to a neutral register.

Semantic content is preserved despite stylistic homogenization.

Abstract

Differential Privacy (DP) for text matured from disjointed word-level substitutions to contiguous sentence-level rewriting by leveraging the generative capacity of language models. While this form of text privatization is best suited for balancing formal privacy guarantees with grammatical coherence, its impact on the register identity of text remains largely unexplored. By conducting a multidimensional stylistic profiling of differentially-private rewriting, we demonstrate that the cost of privacy extends far beyond lexical variation. Specifically, we find that rewriting under privacy constraints induces a systematic functional mutation of the text's communicative signature. This shift is characterized by the severe attrition of interactive markers, contextual references, and complex subordination. By comparing autoregressive paraphrasing against bidirectional substitution across a spectrum of privacy budgets, we observe that both architectures force convergence toward a non-involved and non-persuasive register. This register-blind sanitization effectively preserves semantic content but structurally homogenizes the nuanced stylistic markers that define human-authored discourse.