Who Wrote This? The Key to Zero-Shot LLM-Generated Text Detection Is GECScore

Junchao Wu, Runzhe Zhan, Derek F. Wong, Shu Yang, Xuebo Liu, Lidia S. Chao, Min Zhang


Abstract
The efficacy of detectors for texts generated by large language models (LLMs) substantially depends on the availability of large-scale training data. However, white-box zero-shot detectors, which require no such data, are limited by the accessibility of the source model of the LLM-generated text. In this paper, we propose a simple yet effective black-box zero-shot detection approach based on the observation that, from the perspective of LLMs, human-written texts typically contain more grammatical errors than LLM-generated texts. This approach involves calculating the Grammar Error Correction Score (GECScore) for the given text to differentiate between human-written and LLM-generated text. Experimental results show that our method outperforms current state-of-the-art (SOTA) zero-shot and supervised methods, achieving an average AUROC of 98.62% across XSum and Writing Prompts dataset. Additionally, our approach demonstrates strong reliability in the wild, exhibiting robust generalization and resistance to paraphrasing attacks. Data and code are available at: https://github.com/NLP2CT/GECScore.
Anthology ID:
2025.coling-main.684
Volume:
Proceedings of the 31st International Conference on Computational Linguistics
Month:
January
Year:
2025
Address:
Abu Dhabi, UAE
Editors:
Owen Rambow, Leo Wanner, Marianna Apidianaki, Hend Al-Khalifa, Barbara Di Eugenio, Steven Schockaert
Venue:
COLING
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
10275–10292
Language:
URL:
https://aclanthology.org/2025.coling-main.684/
DOI:
Bibkey:
Cite (ACL):
Junchao Wu, Runzhe Zhan, Derek F. Wong, Shu Yang, Xuebo Liu, Lidia S. Chao, and Min Zhang. 2025. Who Wrote This? The Key to Zero-Shot LLM-Generated Text Detection Is GECScore. In Proceedings of the 31st International Conference on Computational Linguistics, pages 10275–10292, Abu Dhabi, UAE. Association for Computational Linguistics.
Cite (Informal):
Who Wrote This? The Key to Zero-Shot LLM-Generated Text Detection Is GECScore (Wu et al., COLING 2025)
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PDF:
https://aclanthology.org/2025.coling-main.684.pdf