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LEGO-Puzzles: How Good Are MLLMs at Multi-Step Spatial Reasoning?

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arxiv 2503.19990 v3 pith:RA6IRTQF submitted 2025-03-25 cs.AI

LEGO-Puzzles: How Good Are MLLMs at Multi-Step Spatial Reasoning?

classification cs.AI
keywords reasoningspatialmllmslego-puzzlesunderstandingmulti-stepsequentialtasks
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Multi-step spatial reasoning entails understanding and reasoning about spatial relationships across multiple sequential steps, which is crucial for tackling complex real-world applications, such as robotic manipulation, autonomous navigation, and automated assembly. To assess how well current Multimodal Large Language Models (MLLMs) have acquired this fundamental capability, we introduce LEGO-Puzzles, a scalable benchmark designed to evaluate both spatial understanding and sequential reasoning in MLLMs through LEGO-based tasks. LEGO-Puzzles consists of 1,100 carefully curated visual question-answering (VQA) samples spanning 11 distinct tasks, ranging from basic spatial understanding to complex multi-step reasoning. Based on LEGO-Puzzles, we conduct a comprehensive evaluation of 20 state-of-the-art MLLMs and uncover significant limitations in their spatial reasoning capabilities: even the most powerful MLLMs can answer only about half of the test cases, whereas human participants achieve over 90% accuracy. Furthermore, based on LEGO-Puzzles, we design generation tasks to investigate whether MLLMs can transfer their spatial understanding and reasoning abilities to image generation. Our experiments show that only GPT-4o and Gemini-2.0-Flash exhibit a limited ability to follow these instructions, while other MLLMs either replicate the input image or generate completely irrelevant outputs. Overall, LEGO-Puzzles exposes critical deficiencies in existing MLLMs' spatial understanding and sequential reasoning capabilities, and underscores the need for further advancements in multimodal spatial reasoning.

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Cited by 13 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. VGenST-Bench: A Benchmark for Spatio-Temporal Reasoning via Active Video Synthesis

    cs.CV 2026-05 unverdicted novelty 7.0

    VGenST-Bench is a new video benchmark for MLLM spatio-temporal reasoning built via generative synthesis, a multi-agent pipeline with human oversight, a 3x2x2 taxonomy, and hierarchical tasks separating perception from...

  2. SpaceVista: All-Scale Visual Spatial Reasoning from mm to km

    cs.CV 2025-10 conditional novelty 7.0

    SpaceVista contributes a 1M-QA, 38K-video all-scale spatial reasoning dataset spanning mm to km, a manually verified benchmark, and a fine-tuned 7B MLLM with scale experts and progressive reward training.

  3. Vesta: A Generalist Embodied Reasoning Model

    cs.RO 2026-06 unverdicted novelty 6.0

    Vesta is a unified embodied generalist model that outperforms specialist baselines by over 20% on average and improves real-world robotic task success by over 35%.

  4. Seeing Time: Benchmarking Chronological Reasoning and Shortcut Biases in Vision-Language Models

    cs.AI 2026-06 unverdicted novelty 6.0

    Introduces ChronoVision benchmark with three datasets showing VLMs rely on superficial cues such as color filters rather than genuine chronological reasoning.

  5. Brick-Composer: Using MLLMs for Assembly with Diverse Bricks

    cs.AI 2026-06 unverdicted novelty 6.0

    Brick-Composer trains MLLMs on brick assembly via three signals, raising step-level success from under 1% to around 15% on the new BC-Bench benchmark.

  6. Flat-Pack Bench: Evaluating Spatio-Temporal Understanding in Large Vision-Language Models through Furniture Assembly

    cs.CV 2026-05 unverdicted novelty 6.0

    Flat-Pack Bench is a new evaluation suite that shows state-of-the-art LVLMs perform poorly on nuanced spatio-temporal reasoning required for furniture assembly videos.

  7. Do MLLMs Really Understand Space? A Mathematical Reasoning Evaluation

    cs.AI 2026-02 unverdicted novelty 6.0

    MLLMs show a large gap in spatial mathematical reasoning compared to humans, and a new 10,000-problem dataset helps narrow it through training.

  8. Diagnosing Corruption-Induced Reliability Failures in Vision-Language Models

    cs.CV 2025-11 conditional novelty 6.0

    Mild visual corruption can boost a vision-language model's top-1 accuracy while its confidence–correctness alignment (measured by the new RAS score) degrades.

  9. SpatialThinker: Reinforcing Scene Graph-Grounded Spatial Reasoning via Dense Rewards

    cs.CV 2025-11 conditional novelty 6.0

    Dense scene-graph-grounded rewards let a 7B multimodal LLM trained on 7K synthetic questions beat SFT and sparse-RL baselines and outscore GPT-4o on average across 12 spatial/real-world benchmarks.

  10. Sample-Efficient Post-Training for LEGO Spatial-Physics Reasoning

    cs.LG 2026-05 unverdicted novelty 5.0

    PVPO is a sample-efficient RL method that improves semantic, geometric, and physical quality in LLM LEGO assembly generation by mitigating the PhysHack failure mode where validity alone fails to ensure fidelity.

  11. What's Holding Back Latent Visual Reasoning?

    cs.CV 2026-05 unverdicted novelty 5.0

    Latent visual reasoning fails in current models because standard datasets make oracle latents uninformative and inference-time latents collapse away from useful representations.

  12. Reversing the Flow: Generation-to-Understanding Synergy in Large Multimodal Models

    cs.CV 2026-05 unverdicted novelty 5.0

    Generation-to-Understanding synergy lets multimodal models create self-generated visual edits as intermediate steps, improving performance on twelve benchmarks while revealing limits in task-aligned self-reflection.

  13. The Periodic Table of LLM Reasoning: A Structured Survey of Reasoning Paradigms, Methods, and Failure Modes

    cs.CL 2026-06 unverdicted novelty 4.0

    A literature survey that introduces a taxonomy for LLM reasoning paradigms, analyzes methodological trends, and synthesizes failure modes from over 300 papers.