T-Detect: Tail-Aware Statistical Normalization for Robust Detection of Adversarial Machine-Generated Text

• URL: http://arxiv.org/abs/2507.23577v1
• Date: Thu, 31 Jul 2025 14:08:04 GMT
• Title: T-Detect: Tail-Aware Statistical Normalization for Robust Detection of Adversarial Machine-Generated Text
• Authors: Alva West, Luodan Zhang, Liuliu Zhang, Minjun Zhu, Yixuan Weng, Yue Zhang,
• Abstract summary: Existing zero-shot detectors often rely on statistical measures that implicitly assume Gaussian distributions.<n>This paper introduces T-Detect, a novel detection method that fundamentally redesigns the statistical core of curvature-based detectors.<n>Our contributions are a new, theoretically-justified statistical foundation for text detection, an ablation-validated method that demonstrates superior robustness, and a comprehensive analysis of its performance under adversarial conditions.
• Score: 15.880428198252046
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The proliferation of sophisticated text generation models necessitates the development of robust detection methods capable of identifying machine-generated content, particularly text designed to evade detection through adversarial perturbations. Existing zero-shot detectors often rely on statistical measures that implicitly assume Gaussian distributions, a premise that falters when confronted with the heavy-tailed statistical artifacts characteristic of adversarial or non-native English texts. This paper introduces T-Detect, a novel detection method that fundamentally redesigns the statistical core of curvature-based detectors. Our primary innovation is the replacement of standard Gaussian normalization with a heavy-tailed discrepancy score derived from the Student's t-distribution. This approach is theoretically grounded in the empirical observation that adversarial texts exhibit significant leptokurtosis, rendering traditional statistical assumptions inadequate. T-Detect computes a detection score by normalizing the log-likelihood of a passage against the expected moments of a t-distribution, providing superior resilience to statistical outliers. We validate our approach on the challenging RAID benchmark for adversarial text and the comprehensive HART dataset. Experiments show that T-Detect provides a consistent performance uplift over strong baselines, improving AUROC by up to 3.9\% in targeted domains. When integrated into a two-dimensional detection framework (CT), our method achieves state-of-the-art performance, with an AUROC of 0.926 on the Books domain of RAID. Our contributions are a new, theoretically-justified statistical foundation for text detection, an ablation-validated method that demonstrates superior robustness, and a comprehensive analysis of its performance under adversarial conditions. Ours code are released at https://github.com/ResearAI/t-detect.

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