DialToM: A Theory of Mind Benchmark for Forecasting State-Driven Dialogue Trajectories

Neemesh Yadav, Palakorn Achananuparp, Jing Jiang, Ee-Peng Lim


Abstract
We introduce DialToM, an annotated Theory of Mind (ToM) benchmark built from naturalistic human–human dialogues using a multiple-choice evaluation framework. Concurrent with recent work showing a gap between explicit mental-state inference and applied ToM in synthetic settings (Gu et al. 2024), we establish a stricter State-Driven Diagnostic Probe in which models must forecast state-consistent dialogue trajectories solely from isolated mental-state profiles without dialogue context. Our evaluation reveals a systematic reasoning asymmetry—LLMs excel at inferring mental states (Literal ToM) but struggle to leverage them for social forecasting (Functional ToM). Crucially, a domain expert achieves 100% accuracy on this task, proving its validity and establishing a stark human-AI capability gap. Further, a teacher-student reasoning injection probe shows that Gemini 3 Pro, which establishes the leading baseline, possesses robust Functional ToM capabilities for context-free forecasting that are transferable to weaker models. DialToM, its evaluation code, and dataset are publicly available at https://github.com/Stealth-py/DialToM.
Anthology ID:
2026.emnlp-main.1779
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
40529–40560
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URL:
https://aclanthology.org/2026.emnlp-main.1779/
DOI:
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Cite (ACL):
Neemesh Yadav, Palakorn Achananuparp, Jing Jiang, and Ee-Peng Lim. 2026. DialToM: A Theory of Mind Benchmark for Forecasting State-Driven Dialogue Trajectories. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 40529–40560, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DialToM: A Theory of Mind Benchmark for Forecasting State-Driven Dialogue Trajectories (Yadav et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1779.pdf