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Main Authors: Liu, Hao, Dai, Yiqing, Tan, Haotian, Lei, Yu, Zhou, Yujia, Wu, Zhen
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2510.17880
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author Liu, Hao
Dai, Yiqing
Tan, Haotian
Lei, Yu
Zhou, Yujia
Wu, Zhen
author_facet Liu, Hao
Dai, Yiqing
Tan, Haotian
Lei, Yu
Zhou, Yujia
Wu, Zhen
contents Emotions guide human decisions, but whether large language models (LLMs) use emotion similarly remains unknown. We tested this using altruistic third-party punishment, where an observer incurs a personal cost to enforce fairness, a hallmark of human morality and often driven by negative emotion. In a large-scale comparison of 4,068 LLM agents with 1,159 adults across 796,100 decisions, LLMs used emotion to guide punishment, sometimes even more strongly than humans did: Unfairness elicited stronger negative emotion that led to more punishment; punishing unfairness produced more positive emotion than accepting; and critically, prompting self-reports of emotion causally increased punishment. However, mechanisms diverged: LLMs prioritized emotion over cost, enforcing norms in an almost all-or-none manner with reduced cost sensitivity, whereas humans balanced fairness and cost. Notably, reasoning models (o3-mini, DeepSeek-R1) were more cost-sensitive and closer to human behavior than foundation models (GPT-3.5, DeepSeek-V3), yet remained heavily emotion-driven. These findings provide the first causal evidence of emotion-guided moral decisions in LLMs and reveal deficits in cost calibration and nuanced fairness judgements, reminiscent of early-stage human responses. We propose that LLMs progress along a trajectory paralleling human development; future models should integrate emotion with context-sensitive reasoning to achieve human-like emotional intelligence.
format Preprint
id arxiv_https___arxiv_org_abs_2510_17880
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Outraged AI: Large language models prioritise emotion over cost in fairness enforcement
Liu, Hao
Dai, Yiqing
Tan, Haotian
Lei, Yu
Zhou, Yujia
Wu, Zhen
Computation and Language
Artificial Intelligence
Emotions guide human decisions, but whether large language models (LLMs) use emotion similarly remains unknown. We tested this using altruistic third-party punishment, where an observer incurs a personal cost to enforce fairness, a hallmark of human morality and often driven by negative emotion. In a large-scale comparison of 4,068 LLM agents with 1,159 adults across 796,100 decisions, LLMs used emotion to guide punishment, sometimes even more strongly than humans did: Unfairness elicited stronger negative emotion that led to more punishment; punishing unfairness produced more positive emotion than accepting; and critically, prompting self-reports of emotion causally increased punishment. However, mechanisms diverged: LLMs prioritized emotion over cost, enforcing norms in an almost all-or-none manner with reduced cost sensitivity, whereas humans balanced fairness and cost. Notably, reasoning models (o3-mini, DeepSeek-R1) were more cost-sensitive and closer to human behavior than foundation models (GPT-3.5, DeepSeek-V3), yet remained heavily emotion-driven. These findings provide the first causal evidence of emotion-guided moral decisions in LLMs and reveal deficits in cost calibration and nuanced fairness judgements, reminiscent of early-stage human responses. We propose that LLMs progress along a trajectory paralleling human development; future models should integrate emotion with context-sensitive reasoning to achieve human-like emotional intelligence.
title Outraged AI: Large language models prioritise emotion over cost in fairness enforcement
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2510.17880