TactfulToM: Do LLMs have the Theory of Mind ability to understand White Lies?

Yiwei Liu, Emma Jane Pretty, Jiahao Huang, Saku Sugawara


Abstract
While recent studies explore Large Language Models’ (LLMs) performance on Theory of Mind (ToM) reasoning tasks, research on ToM abilities that require more nuanced social context is limited, such as white lies. We introduce TactfulToM, a novel English benchmark designed to evaluate LLMs’ ability to understand white lies within real-life conversations and reason about prosocial motivations behind them, particularly when they are used to spare others’ feelings and maintain social harmony. Our benchmark is generated through a multi-stage human-in-the-loop pipeline where LLMs expand manually designed seed stories into conversations to maintain the information asymmetry between participants necessary for authentic white lies. We show that TactfulToM is challenging for state-of-the-art models, which perform substantially below humans, revealing shortcomings in their ability to fully comprehend the ToM reasoning that enables true understanding of white lies.
Anthology ID:
2025.emnlp-main.1272
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
25054–25072
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URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1272/
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Bibkey:
Cite (ACL):
Yiwei Liu, Emma Jane Pretty, Jiahao Huang, and Saku Sugawara. 2025. TactfulToM: Do LLMs have the Theory of Mind ability to understand White Lies?. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 25054–25072, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
TactfulToM: Do LLMs have the Theory of Mind ability to understand White Lies? (Liu et al., EMNLP 2025)
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