Understanding the Effects of RLHF on the Quality and Detectability of LLM-Generated Texts

Fuente: arXiv
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Autores principales: Xu, Beining, Zubiaga, Arkaitz
Formato: Preprint
Publicado: 2025
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author Xu, Beining
Zubiaga, Arkaitz
author_facet Xu, Beining
Zubiaga, Arkaitz
contents Large Language Models (LLMs) have demonstrated exceptional performance on a range of downstream NLP tasks by generating text that closely resembles human writing. However, the ease of achieving this similarity raises concerns from potential malicious uses at scale by bad actors, as LLM-generated text becomes increasingly difficult to discern from human text. Although detection methods have been developed to address this issue, bad actors can further manipulate LLM-generated texts to make them less detectable. In this work, we study how further editing texts with Reinforcement Learning from Human Feedback (RLHF), which aligns model outputs with human preferences, affects (a) the quality of generated texts for two tasks, and (b) the performance of LLM-generated text detectors, looking at both training-based and zero-shot detection methods. Although RLHF improves the quality of LLM-generated texts, we find that it also tends to produce more detectable, lengthy, and repetitive outputs. Additionally, we observe that training-based detectors are vulnerable to short texts and to texts that incorporate code, whereas zero-shot detectors exhibit greater robustness.
format Preprint
id arxiv_https___arxiv_org_abs_2503_17965
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Understanding the Effects of RLHF on the Quality and Detectability of LLM-Generated Texts
Xu, Beining
Zubiaga, Arkaitz
Computation and Language
Artificial Intelligence
68T50
I.2.7
Large Language Models (LLMs) have demonstrated exceptional performance on a range of downstream NLP tasks by generating text that closely resembles human writing. However, the ease of achieving this similarity raises concerns from potential malicious uses at scale by bad actors, as LLM-generated text becomes increasingly difficult to discern from human text. Although detection methods have been developed to address this issue, bad actors can further manipulate LLM-generated texts to make them less detectable. In this work, we study how further editing texts with Reinforcement Learning from Human Feedback (RLHF), which aligns model outputs with human preferences, affects (a) the quality of generated texts for two tasks, and (b) the performance of LLM-generated text detectors, looking at both training-based and zero-shot detection methods. Although RLHF improves the quality of LLM-generated texts, we find that it also tends to produce more detectable, lengthy, and repetitive outputs. Additionally, we observe that training-based detectors are vulnerable to short texts and to texts that incorporate code, whereas zero-shot detectors exhibit greater robustness.
title Understanding the Effects of RLHF on the Quality and Detectability of LLM-Generated Texts
topic Computation and Language
Artificial Intelligence
68T50
I.2.7
url https://arxiv.org/abs/2503.17965