The MASK Benchmark: Disentangling Honesty From Accuracy in AI Systems
On the map: LLM agents and tool use → Social simulation and multi-agent debate
Abstract (arXiv)
As large language models (LLMs) become more capable and agentic, the requirement for trust in their outputs grows significantly, yet at the same time concerns have been mounting that models may learn to lie in pursuit of their goals. To address these concerns, a body of work has emerged around the notion of "honesty" in LLMs, along with interventions aimed at mitigating deceptive behaviors. However, some benchmarks claiming to measure honesty in fact simply measure accuracy--the correctness of a model's beliefs--in disguise. Moreover, no benchmarks currently exist for directly measuring whether language models lie. In this work, we introduce a large-scale human-collected dataset for directly measuring lying, allowing us to disentangle accuracy from honesty. Across a diverse set of LLMs, we find that while larger models obtain higher accuracy on our benchmark, they do not become more honest. Surprisingly, most frontier LLMs obtain high scores on truthfulness benchmarks yet exhibit a substantial propensity to lie under pressure, resulting in low honesty scores on our benchmark. We find that simple methods, such as representation engineering interventions, can improve honesty. These results underscore the growing need for robust evaluations and effective interventions to ensure LLMs remain trustworthy.
Key facts. Cited by 72 papers in the map (data through 14 Oct 2026). Placed in Social simulation and multi-agent debate, one of 16 directions in LLM agents and tool use. Builds on 31 of its 39 references that are in the map. First posted on arXiv 5 Mar 2025.
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31 of 39 references.
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Other references · 30
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Citing papers per year: 2025: 19; 2026: 53.
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- 2026Pre-training interventions, ex post facto: Grafting model beliefs across checkpoints30 Sep 2026
- 2026Language Models Are "Insecure" Reporters28 Sep 2026
- 2026Strangers to Themselves: What Language Models Say About Themselves Is Generic9 Sep 2026
- 2026Beliefs and Behavior in Language Models7 Sep 2026
- 2026Automated Researchers Can Mitigate Well-characterized Alignment Failures28 Aug 2026
- 2026Evaluation Awareness in Language Models: Representation, Verbalization, and Control22 Aug 2026
- 2026Constitutional Midtraining: Content Presence Drives Alignment Gains29 Jul 2026
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