Label Effects: Shared Heuristic Reliance in Trust Assessment by Humans and LLM-as-a-Judge

Fuente: arXiv
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Auteurs principaux: Sun, Xin, Wu, Di, Qin, Sijing, Echizen, Isao, Ali, Abdallah El, Sugawara, Saku
Format: Preprint
Publié: 2026
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author Sun, Xin
Wu, Di
Qin, Sijing
Echizen, Isao
Ali, Abdallah El
Sugawara, Saku
author_facet Sun, Xin
Wu, Di
Qin, Sijing
Echizen, Isao
Ali, Abdallah El
Sugawara, Saku
contents Large language models (LLMs) are increasingly used as automated evaluators (LLM-as-a-Judge). This work challenges its reliability by showing that trust judgments by LLMs are biased by disclosed source labels. Using a counterfactual design, we find that both humans and LLM judges assign higher trust to information labeled as human-authored than to the same content labeled as AI-generated. Eye-tracking data reveal that humans rely heavily on source labels as heuristic cues for judgments. We analyze LLM internal states during judgment. Across label conditions, models allocate denser attention to the label region than the content region, and this label dominance is stronger under Human labels than AI labels, consistent with the human gaze patterns. Besides, decision uncertainty measured by logits is higher under AI labels than Human labels. These results indicate that the source label is a salient heuristic cue for both humans and LLMs. It raises validity concerns for label-sensitive LLM-as-a-Judge evaluation, and we cautiously raise that aligning models with human preferences may propagate human heuristic reliance into models, motivating debiased evaluation and alignment.
format Preprint
id arxiv_https___arxiv_org_abs_2604_05593
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Label Effects: Shared Heuristic Reliance in Trust Assessment by Humans and LLM-as-a-Judge
Sun, Xin
Wu, Di
Qin, Sijing
Echizen, Isao
Ali, Abdallah El
Sugawara, Saku
Artificial Intelligence
Computation and Language
Large language models (LLMs) are increasingly used as automated evaluators (LLM-as-a-Judge). This work challenges its reliability by showing that trust judgments by LLMs are biased by disclosed source labels. Using a counterfactual design, we find that both humans and LLM judges assign higher trust to information labeled as human-authored than to the same content labeled as AI-generated. Eye-tracking data reveal that humans rely heavily on source labels as heuristic cues for judgments. We analyze LLM internal states during judgment. Across label conditions, models allocate denser attention to the label region than the content region, and this label dominance is stronger under Human labels than AI labels, consistent with the human gaze patterns. Besides, decision uncertainty measured by logits is higher under AI labels than Human labels. These results indicate that the source label is a salient heuristic cue for both humans and LLMs. It raises validity concerns for label-sensitive LLM-as-a-Judge evaluation, and we cautiously raise that aligning models with human preferences may propagate human heuristic reliance into models, motivating debiased evaluation and alignment.
title Label Effects: Shared Heuristic Reliance in Trust Assessment by Humans and LLM-as-a-Judge
topic Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2604.05593