Decoupling Content and Expression: Two-Dimensional Detection of AI-Generated Text

The wide usage of LLMs raises critical requirements on detecting AI participation in texts. Existing studies investigate these detections in scattered contexts, leaving a systematic and unified approach unexplored. In this paper, we present HART, a hierarchical framework of AI risk levels, each corresponding to a detection task. To address these tasks, we propose a novel 2D Detection Method, decoupling a text into content and language expression. Our findings show that content is resistant to surface-level changes, which can serve as a key feature for detection. Experiments demonstrate that 2D method significantly outperforms existing detectors, achieving an AUROC improvement from 0.705 to 0.849 for level-2 detection and from 0.807 to 0.886 for RAID. We release our data and code atthis https URL.

@article{bao2025_2503.00258,
  title={ Decoupling Content and Expression: Two-Dimensional Detection of AI-Generated Text },
  author={ Guangsheng Bao and Lihua Rong and Yanbin Zhao and Qiji Zhou and Yue Zhang },
  journal={arXiv preprint arXiv:2503.00258},
  year={ 2025 }
}