LoVeC: Reinforcement Learning for Better Verbalized Confidence in Long-Form Generations

Fuente: arXiv
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Autori principali: Zhang, Caiqi, Zhu, Xiaochen, Li, Chengzu, Collier, Nigel, Vlachos, Andreas
Natura: Preprint
Pubblicazione: 2025
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author Zhang, Caiqi
Zhu, Xiaochen
Li, Chengzu
Collier, Nigel
Vlachos, Andreas
author_facet Zhang, Caiqi
Zhu, Xiaochen
Li, Chengzu
Collier, Nigel
Vlachos, Andreas
contents Hallucination remains a major challenge for the safe and trustworthy deployment of large language models (LLMs) in factual content generation. Prior work has explored confidence estimation as an effective approach to hallucination detection, but often relies on post-hoc self-consistency methods that require computationally expensive sampling. Verbalized confidence offers a more efficient alternative, but existing approaches are largely limited to short-form question answering (QA) tasks and do not generalize well to open-ended generation. In this paper, we propose LoVeC (Long-form Verbalized Confidence), a novel reinforcement learning based method that trains LLMs to append an on-the-fly numerical confidence score to each generated statement during long-form generation. The confidence score serves as a direct and interpretable signal of the factuality of generation. We introduce two evaluation settings, free-form tagging and iterative tagging, to assess different verbalized confidence estimation methods. Experiments on three long-form QA datasets show that our RL-trained models achieve better calibration and generalize robustly across domains. Also, our method is highly efficient, being 20 times faster than traditional self-consistency methods while achieving better calibration.
format Preprint
id arxiv_https___arxiv_org_abs_2505_23912
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle LoVeC: Reinforcement Learning for Better Verbalized Confidence in Long-Form Generations
Zhang, Caiqi
Zhu, Xiaochen
Li, Chengzu
Collier, Nigel
Vlachos, Andreas
Computation and Language
Artificial Intelligence
Hallucination remains a major challenge for the safe and trustworthy deployment of large language models (LLMs) in factual content generation. Prior work has explored confidence estimation as an effective approach to hallucination detection, but often relies on post-hoc self-consistency methods that require computationally expensive sampling. Verbalized confidence offers a more efficient alternative, but existing approaches are largely limited to short-form question answering (QA) tasks and do not generalize well to open-ended generation. In this paper, we propose LoVeC (Long-form Verbalized Confidence), a novel reinforcement learning based method that trains LLMs to append an on-the-fly numerical confidence score to each generated statement during long-form generation. The confidence score serves as a direct and interpretable signal of the factuality of generation. We introduce two evaluation settings, free-form tagging and iterative tagging, to assess different verbalized confidence estimation methods. Experiments on three long-form QA datasets show that our RL-trained models achieve better calibration and generalize robustly across domains. Also, our method is highly efficient, being 20 times faster than traditional self-consistency methods while achieving better calibration.
title LoVeC: Reinforcement Learning for Better Verbalized Confidence in Long-Form Generations
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2505.23912