ResearchResearch paperReinforcement Learning · Large Language Models · Robotics & Embodied AI1 source · Oct 12, 2026

The belief-action gap in language model agents

We study how state beliefs, action values, and action preferences interact as LM agents reason and commit to decisions in text-rendered grid worlds.

Key points

  • Language model (LM) agents can fail for different reasons, requiring different explanations and interventions.
  • We estimate task-relevant beliefs using report-based and representation-based probes, and action values using inverse reinforcement learning.
  • We find that task-relevant state and value information is often represented more reliably than it is reflected in behaviour.
  • Tracking action preferences throughout reasoning further shows that decisions sharpen around a commitment point and reported belief uncertainty decreases near commitment, although individual belief changes do not consistently explain shifts in action preference.

Sources (1)

  • [1]The belief-action gap in language model agents
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 12, 10:04 PM
    We study how state beliefs, action values, and action preferences interact as LM agents reason and commit to decisions in text-rendered grid worlds.
    Language model (LM) agents can fail for different reasons, requiring different explanations and interventions.

Extractive summary: sentences quoted from the sources.

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