Machine Text Detectors are Membership Inference Attacks

Fuente: arXiv
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Main Authors: Koike, Ryuto, Dugan, Liam, Kaneko, Masahiro, Callison-Burch, Chris, Okazaki, Naoaki
Format: Preprint
Published: 2025
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author Koike, Ryuto
Dugan, Liam
Kaneko, Masahiro
Callison-Burch, Chris
Okazaki, Naoaki
author_facet Koike, Ryuto
Dugan, Liam
Kaneko, Masahiro
Callison-Burch, Chris
Okazaki, Naoaki
contents Although membership inference attacks (MIAs) and machine-generated text detection target different goals, their methods often exploit similar signals based on a language model's probability distribution, and the two tasks have been studied independently. This can result in conclusions that overlook stronger methods and valuable insights from the other task. In this work, we theoretically and empirically demonstrate the transferability, i.e., how well a method originally developed for one task performs on the other, between MIAs and machine text detection. We prove that the metric achieving asymptotically optimal performance is identical for both tasks. We unify existing methods under this optimal metric and hypothesize that the accuracy with which a method approximates this metric is directly correlated with its transferability. Our large-scale empirical experiments demonstrate very strong rank correlation ($ρ\approx 0.7$) in cross-task performance. Notably, we also find that a machine text detector achieves the strongest performance among evaluated methods on both tasks, demonstrating the practical impact of transferability. To facilitate cross-task development and fair evaluation, we introduce MINT, a unified evaluation suite for MIAs and machine-generated text detection, implementing 15 recent methods from both tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19492
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Machine Text Detectors are Membership Inference Attacks
Koike, Ryuto
Dugan, Liam
Kaneko, Masahiro
Callison-Burch, Chris
Okazaki, Naoaki
Computation and Language
Although membership inference attacks (MIAs) and machine-generated text detection target different goals, their methods often exploit similar signals based on a language model's probability distribution, and the two tasks have been studied independently. This can result in conclusions that overlook stronger methods and valuable insights from the other task. In this work, we theoretically and empirically demonstrate the transferability, i.e., how well a method originally developed for one task performs on the other, between MIAs and machine text detection. We prove that the metric achieving asymptotically optimal performance is identical for both tasks. We unify existing methods under this optimal metric and hypothesize that the accuracy with which a method approximates this metric is directly correlated with its transferability. Our large-scale empirical experiments demonstrate very strong rank correlation ($ρ\approx 0.7$) in cross-task performance. Notably, we also find that a machine text detector achieves the strongest performance among evaluated methods on both tasks, demonstrating the practical impact of transferability. To facilitate cross-task development and fair evaluation, we introduce MINT, a unified evaluation suite for MIAs and machine-generated text detection, implementing 15 recent methods from both tasks.
title Machine Text Detectors are Membership Inference Attacks
topic Computation and Language
url https://arxiv.org/abs/2510.19492