Active Layer-Contrastive Decoding Reduces Hallucination in Large Language Model Generation

Fuente: arXiv
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Autores principales: Zhang, Hongxiang, Chen, Hao, Chen, Muhao, Zhang, Tianyi
Formato: Preprint
Publicado: 2025
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author Zhang, Hongxiang
Chen, Hao
Chen, Muhao
Zhang, Tianyi
author_facet Zhang, Hongxiang
Chen, Hao
Chen, Muhao
Zhang, Tianyi
contents Recent decoding methods improve the factuality of large language models (LLMs) by refining how the next token is selected during generation. These methods typically operate at the token level, leveraging internal representations to suppress superficial patterns. Nevertheless, LLMs remain prone to hallucinations, especially over longer contexts. In this paper, we propose Active Layer-Contrastive Decoding (ActLCD), a novel decoding strategy that actively decides when to apply contrasting layers during generation. By casting decoding as a sequential decision-making problem, ActLCD employs a reinforcement learning policy guided by a reward-aware classifier to optimize factuality beyond the token level. Our experiments demonstrate that ActLCD surpasses state-of-the-art methods across five benchmarks, showcasing its effectiveness in mitigating hallucinations in diverse generation scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2505_23657
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Active Layer-Contrastive Decoding Reduces Hallucination in Large Language Model Generation
Zhang, Hongxiang
Chen, Hao
Chen, Muhao
Zhang, Tianyi
Computation and Language
Artificial Intelligence
Machine Learning
Recent decoding methods improve the factuality of large language models (LLMs) by refining how the next token is selected during generation. These methods typically operate at the token level, leveraging internal representations to suppress superficial patterns. Nevertheless, LLMs remain prone to hallucinations, especially over longer contexts. In this paper, we propose Active Layer-Contrastive Decoding (ActLCD), a novel decoding strategy that actively decides when to apply contrasting layers during generation. By casting decoding as a sequential decision-making problem, ActLCD employs a reinforcement learning policy guided by a reward-aware classifier to optimize factuality beyond the token level. Our experiments demonstrate that ActLCD surpasses state-of-the-art methods across five benchmarks, showcasing its effectiveness in mitigating hallucinations in diverse generation scenarios.
title Active Layer-Contrastive Decoding Reduces Hallucination in Large Language Model Generation
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2505.23657