Evaluating Theory of Mind in Reasoning Models: Robustness over Reasoning

arXiv:2608.04646 · cs.CL · Submitted 2026-08-05 · Read on arXiv

Ian B. de Haan, Peter van der Putten, Max van Duijn

cs.CL

Submitted: 2026-08-05

Comments: Accepted for 29th International Conference on Discovery Science, October 5-9, 2026, Mainz, Germany

License: http://creativecommons.org/licenses/by-nc-sa/4.0/

The gist: Large language models (LLMs) have recently shown strong performance on Theory of Mind (ToM) tests, prompting debate about the nature and validity of the underlying capabilities.

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Abstract

Large language models (LLMs) have recently shown strong performance on Theory of Mind (ToM) tests, prompting debate about the nature and validity of the underlying capabilities. At the same time, reasoning-oriented LLMs trained via reinforcement learning with verifiable rewards have demonstrated notable improvements across a range of benchmarks. In this work, we examine the behavior of such reasoning models in ToM tasks using novel adaptations of machine psychological experiments together with results from established benchmarks. We observe that reasoning models consistently exhibit increased robustness to prompt variations and task perturbations. Our analysis suggests these gains come at least partly from models being more robust at reaching the correct answer under prompt and task variation. We read this as evidence for a robustness-based account rather than for a new ToM-specific ability.

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