Research map / Multi-agent systems and games / LLM agents
Hypothetical Minds: Scaffolding Theory of Mind for Multi-Agent Tasks with Large Language Models
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Introduces Hypothetical Minds, an LLM-based embodied agent whose Theory of Mind module generates, evaluates (via Rescorla-Wagner value updates) and refines natural-language hypotheses about other agents, evaluated on Melting Pot scenarios.
Problem
MARL methods struggle with non-stationarity, sample efficiency, and generalization to novel agents in multi-agent social environments; LLM agents have mainly been limited to collaborative settings.
Approach
A cognitively inspired LLM agent whose ToM module generates natural-language hypotheses about other agents' strategies, scores them by predictive accuracy using a Rescorla-Wagner value update with intrinsic reward, refines top-k hypotheses, and conditions high-level planning on validated hypotheses.
Key results
- HM achieves the highest reward on 9/9 RWS Repeated scenarios (e.g., 50.8 on scenario 0 vs. 21.0 for Reflexion and 0.0 for OPRE).
- HM is best on 6/8 RWS Arena scenarios and on all 3 Collaborative Cooking Asymmetric partner scenarios (e.g., 628.3 vs. 292.6 for Reflexion on skilled partner).
- On Prisoner's Dilemma, HM is the best LLM agent in 5/10 scenarios, but OPRE achieves the highest reward overall.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Replace single-call Vanilla Mind Prompting with separate calls for reasoning steps in Modular Mind Prompting (ablation) | Hypothetical Minds · Running With Scissors Repeated | average reward | Helped |
| Add hypothesis evaluation to Modular Mind Prompting (ablation) | Hypothetical Minds · Running With Scissors Repeated | average reward | Helped |
| Add hypothesis refinement to MMP + Hypothesis Evaluation (ablation) | Hypothetical Minds · Running With Scissors Repeated | average reward | Helped |
| Remove ToM-specific prompting while retaining hypothesis evaluation and refinement (ablation) | Hypothetical Minds · Running With Scissors Repeated | average reward | Mixed |
| Retain hypotheses beyond the last generated one by using top_k greater than 0 (ablation) | Hypothetical Minds · Running With Scissors Repeated | average reward | Helped |
| Increase top_k beyond 3 (ablation) | Hypothetical Minds · Running With Scissors Repeated | average reward | No clear effect |
| Increase top_k past 5 (ablation) | Hypothetical Minds · Running With Scissors Repeated | average reward | Hurt |
| Vary the hypothesis-value learning rate α (ablation) | Hypothetical Minds with Llama-3-70B-Instruct · Running With Scissors Repeated | average reward | No clear effect |
| Vary the hypothesis validation threshold (ablation) | Hypothetical Minds with Llama-3-70B-Instruct · Running With Scissors Repeated | average reward | No clear effect |
| Replace GPT-4 with GPT-3.5 as the base LLM (ablation) | Hypothetical Minds · Melting Pot environments | average reward | Hurt |
| Replace GPT-4 with Llama-3-70B-Instruct as the base LLM (ablation) | Hypothetical Minds · Melting Pot environments | average reward | Mixed |
Surprising findings
- OPRE, a MARL method designed for an earlier RWS version, gets near-zero reward on nearly every RWS Repeated scenario.
- Higher ToM costs (>$10 per episode) correlate with lower performance because successful hypothesis validation reduces subsequent LLM calls.
Limitations
- Requires human-designed scaffolding, prompts, and encoded game rules rather than learning them from the environment.
- LLM agents lack low-level spatial control; HM travels inefficiently to collect resources, losing to OPRE on Prisoner's Dilemma.
- Llama-3 could not be evaluated on RWS Arena due to context length limits.
Experimental setup
Datasets: Melting Pot 2.0 substrates (Running With Scissors Repeated, Running With Scissors Arena, Collaborative Cooking Asymmetri
Benchmarks: Melting Pot 2.0 RWS Repeated Melting Pot RWS Arena Melting Pot Collaborative Cooking Asymmetric Melting Pot Prisoner's Dilemma in the Matrix Repeated
Metrics: average reward per episode SEM
Baselines: ReAct Reflexion PlanReAct PPO OPRE Vanilla Mind Prompting Modular Mind Prompting
Builds on: Generative Agents ReAct Reflexion Tree-of-Thoughts OPRE
Closest papers by meaning
- Mental-Models for Multi-Agent Systems (NeurIPS 2026 · similarity 0.91)
- Adaptive Theory of Mind for LLM-based Multi-Agent Coordination (AAAI 2026 · similarity 0.89)
- ReMA: Learning to Meta-Think for LLMs with Multi-agent Reinforcement Learning (NeurIPS 2025 · similarity 0.89)
- Reflection-Bench: Evaluating Epistemic Agency in Large Language Models (ICML 2025 · similarity 0.88)
- Adaptive Collaboration with Humans: Metacognitive Policy Optimization for Multi-Agent LLMs with Continual Learning (ICLR 2026 · similarity 0.88)
- AutoToM: Scaling Model-based Mental Inference via Automated Agent Modeling (NeurIPS 2025 · similarity 0.88)
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