Explaining Generalization of AI-Generated Text Detectors Through Linguistic Analysis
This work addresses the generalization problem in AI-text detection for researchers and practitioners, but it is incremental as it builds on prior observations with a systematic analysis.
The study investigated why AI-text detectors fail to generalize across different generation conditions by analyzing linguistic features, finding that generalization performance correlates with specific features like tense usage and pronoun frequency.
AI-text detectors achieve high accuracy on in-domain benchmarks, but often struggle to generalize across different generation conditions such as unseen prompts, model families, or domains. While prior work has reported these generalization gaps, there are limited insights about the underlying causes. In this work, we present a systematic study aimed at explaining generalization behavior through linguistic analysis. We construct a comprehensive benchmark that spans 6 prompting strategies, 7 large language models (LLMs), and 4 domain datasets, resulting in a diverse set of human- and AI-generated texts. Using this dataset, we fine-tune classification-based detectors on various generation settings and evaluate their cross-prompt, cross-model, and cross-dataset generalization. To explain the performance variance, we compute correlations between generalization accuracies and feature shifts of 80 linguistic features between training and test conditions. Our analysis reveals that generalization performance for specific detectors and evaluation conditions is significantly associated with linguistic features such as tense usage and pronoun frequency.