Two Pathways to Truthfulness: On the Intrinsic Encoding of LLM Hallucinations

Fuente: arXiv
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Autores principales: Luo, Wen, Peng, Guangyue, Li, Wei, Wei, Shaohang, Song, Feifan, Wang, Liang, Yang, Nan, Zhang, Xingxing, Jin, Jing, Wei, Furu, Wang, Houfeng
Formato: Preprint
Publicado: 2026
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author Luo, Wen
Peng, Guangyue
Li, Wei
Wei, Shaohang
Song, Feifan
Wang, Liang
Yang, Nan
Zhang, Xingxing
Jin, Jing
Wei, Furu
Wang, Houfeng
author_facet Luo, Wen
Peng, Guangyue
Li, Wei
Wei, Shaohang
Song, Feifan
Wang, Liang
Yang, Nan
Zhang, Xingxing
Jin, Jing
Wei, Furu
Wang, Houfeng
contents Despite their impressive capabilities, large language models (LLMs) frequently generate hallucinations. Previous work shows that their internal states encode rich signals of truthfulness, yet the origins and mechanisms of these signals remain unclear. In this paper, we demonstrate that truthfulness cues arise from two distinct information pathways: (1) a Question-Anchored pathway that depends on question-answer information flow, and (2) an Answer-Anchored pathway that derives self-contained evidence from the generated answer itself. First, we validate and disentangle these pathways through attention knockout and token patching. Afterwards, we uncover notable and intriguing properties of these two mechanisms. Further experiments reveal that (1) the two mechanisms are closely associated with LLM knowledge boundaries; and (2) internal representations are aware of their distinctions. Finally, building on these insightful findings, two applications are proposed to enhance hallucination detection performance. Overall, our work provides new insight into how LLMs internally encode truthfulness, offering directions for more reliable and self-aware generative systems.
format Preprint
id arxiv_https___arxiv_org_abs_2601_07422
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Two Pathways to Truthfulness: On the Intrinsic Encoding of LLM Hallucinations
Luo, Wen
Peng, Guangyue
Li, Wei
Wei, Shaohang
Song, Feifan
Wang, Liang
Yang, Nan
Zhang, Xingxing
Jin, Jing
Wei, Furu
Wang, Houfeng
Computation and Language
Artificial Intelligence
Despite their impressive capabilities, large language models (LLMs) frequently generate hallucinations. Previous work shows that their internal states encode rich signals of truthfulness, yet the origins and mechanisms of these signals remain unclear. In this paper, we demonstrate that truthfulness cues arise from two distinct information pathways: (1) a Question-Anchored pathway that depends on question-answer information flow, and (2) an Answer-Anchored pathway that derives self-contained evidence from the generated answer itself. First, we validate and disentangle these pathways through attention knockout and token patching. Afterwards, we uncover notable and intriguing properties of these two mechanisms. Further experiments reveal that (1) the two mechanisms are closely associated with LLM knowledge boundaries; and (2) internal representations are aware of their distinctions. Finally, building on these insightful findings, two applications are proposed to enhance hallucination detection performance. Overall, our work provides new insight into how LLMs internally encode truthfulness, offering directions for more reliable and self-aware generative systems.
title Two Pathways to Truthfulness: On the Intrinsic Encoding of LLM Hallucinations
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2601.07422