Organizations: Iowa State University, Ames, IA 50011, USA · Tulane University, New Orleans, LA 70118, USA · Princeton University, Princeton, NJ 08544, USA
Video generation models produce visually coherent content but struggle with tasks requiring spatial reasoning and multi-step planning. Reinforcement learning (RL) offers a path to improve generalization, but its effectiveness in video reasoning hinges on reward design -- a challenge that has received little systematic study. We investigate this problem by adapting Group Relative Policy Optimization (GRPO) to flow-based video models and training them on maze-solving and robotic navigation tasks. We first show that multimodal reward models fail catastrophically in this setting. To address this, we design verifiable reward functions grounded in objective task metrics. For structured game environments, we introduce a multi-component trajectory reward. For robotic navigation, we propose an embedding-level verifiable reward. Our experiments show that RL fine-tuning with verifiable rewards improves generalization. For example, on complex 3D mazes, our model improves exact match accuracy by 29.1% over the SFT baseline, and on trap-avoidance tasks by 51.4%. Our systematic reward analysis reveals that verifiable rewards are critical for stable training, while multimodal reward models could lead to degenerate solutions. These findings establish verifiable reward design as a key enabler for robust video reasoning. Code will be publicly available.
Figures & tables
Figure 1: VLLM fails to provide reliable reward, verified rewards can guarantee correct supervision.
Figure 2: Flow-GRPO with verified reward.
Method
EM ( ↑ )
SR ( ↑ )
PR ( ↑ )
SD ( ↓ )
Base
Irreg
Trap
3D
Soko
Base
Irreg
Trap
3D
Soko
Base
Irreg
Trap
3D
Soko
Base
Irreg
Trap
3D
Soko
General Video Model
Closed-Source
Veo-3.1-fast
0.0
0.0
0.0
0.0
2.8
40.3
36.1
38.9
48.6
43.1
20.2
24.8
28.2
13.4
21.7
195.3
111.5
80.7
33.5
112.3
Veo-3.1-pro
0.0
4.2
1.4
0.0
0.0
47.2
36.1
59.7
50.0
37.5
24.6
33.9
39.1
18.0
21.4
140.7
94.5
85.4
40.1
141.8
Sora-2
1.4
5.6
0.0
0.0
4.2
75.0
72.2
83.0
37.5
43.1
45.1
45.7
46.6
19.3
27.4
302.9
187.0
145.1
92.4
138.7
kling-v1
0.0
0.0
0.0
0.0
0.0
2.8
0.0
1.4
27.8
12.5
6.3
8.8
10.4
11.7
9.0
25.2
–
–
69.7
356.1
Table 1: VR-Bench comprises five tasks: Base (Regular Maze), Irreg (Irregular Maze), Trap (TrapField), 3D (3D Maze), and Soko (Sokoban). Last row shows the performance gain compared with Wan2.2-TI2V base model.
Task
EM
SR
PR
SD
E
M
H
E
M
H
E
M
H
E
M
H
Base
0.0
0.0
0.0
8.3
8.3
4.2
13.2
3.8
2.7
154.8
–
–
0.0 ( +0.0 )
4.2 ( +4.2 )
0.0 ( +0.0 )
83.3 ( +75.0 )
41.7 ( +33.4 )
58.3 ( +54.1 )
40.1 ( +26.9 )
26.1 ( +22.3 )
6.0 ( +3.3 )
28.2 ( -126.6 )
10.1 ( – )
– ( – )
87.5 ( +87.5 )
66.7 ( +66.7 )
29.2 ( +29.2 )
100.0 ( +91.7 )
87.5 ( +79.2 )
41.7 ( +37.5 )
97.0 ( +83.8 )
85.4 ( +81.6 )
57.2 ( +54.5 )
1.4 ( -153.4 )
2.5 ( – )
14.6 ( – )
Irrg
0.0
0.0
0.0
29.2
4.2
4.2
13.4
8.1
5.8
48.3
–
39.3
83.3 ( +83.3 )
66.7 ( +66.7 )
54.2 ( +54.2 )
95.8 ( +66.6 )
87.5 ( +83.3 )
62.5 ( +58.3 )
88.0 ( +74.6 )
74.8 ( +66.7 )
68.4 ( +62.6 )
3.5 ( -44.8 )
7.8 ( – )
3.1 ( -36.2 )
Table 2: Difficulty generalization performance of Wan-R1 on VR-Bench. Each task block presents a comparison between the baseline model (Wan2.2-TI2V-5B) and Wan-SFT (trained exclusively on Easy-level data) and Wan-R1 (trained on easy tasks with flow-GRPO) evaluated across three difficulty levels (E/M/H = Easy/Medium/Hard).
Figure 3: Target-Bench results. Wan-R1 achieves the highest overall score, with lower displacement errors (ADE, FDE) and miss rate, and higher soft endpoint (SE) and approach consistency (AC) compared to both the base model and Wan-SFT.
Table 3: Ablation studies on KL regularization and denoising reduction.
Appendix figures & tables10 assets
Supplementary material from the paper’s appendix.
Appendix
Hyperparameter
Value
Group size
G=8
LoRA rank
r=32
Number of frames
193
Training Epoch
Ttrain=1
Inference denoising steps
Sinfer=50
KL coefficient
βKL=0.04
Appendix
Table 4: Training Hyperparameters
Task
Model
EM
SR
PR
SD
Base
Irreg
3D
Soko
Base
Irreg
3D
Soko
Base
Irreg
3D
Soko
Base
Irreg
3D
Soko
Wan2.2-TI2V-5B Baseline
0.0
0.0
0.0
0.0
6.9
12.5
31.9
11.1
6.6
9.1
12.8
9.2
388.7
66.1
5.4
176.6
Regular Maze
Wan-SFT
33.3 (+33.3)
5.6 (+5.6)
0.0 (+0.0)
0.0 (+0.0)
76.4 (+69.5)
8.3 (-4.2)
69.4 (+37.5)
30.6 (+19.5)
60.6 (+54.0)
22.7 (+13.6)
13.7 (+0.9)
19.0 (+9.8)
10.3 (-378.4)
51.7 (-14.4)
12.7 (+7.3)
49.3 (-127.3)
Wan-R1
61.1 (+61.1)
4.2 (+4.2)
0.0 (+0.0)
0.0 (+0.0)
75.0 (+68.1)
13.7 (+1.2)
63.9 (+32.0)
15.3 (+4.2)
78.6 (+72.0)
23.9 (+14.8)
13.1 (+0.3)
20.6 (+11.4)
5.2 (-383.5)
27.1 (-39.0)
10.9 (+5.5)
9.0 (-167.6)
Irregular Maze
Wan-SFT
0.0 (+0.0)
56.9 (+56.9)
0.0 (+0.0)
0.0 (+0.0)
11.1 (+4.2)
69.4 (+56.9)
79.2 (+47.3)
12.5 (+1.4)
16.6 (+10.0)
71.6 (+62.5)
16.8 (+4.0)
15.5 (+6.3)
35.8 (-352.9)
2.4 (-63.7)
9.0 (+3.6)
40.7 (-135.9)
Wan-R1
0.0 (+0.0)
47.9 (+47.9)
0.0 (+0.0)
0.0 (+0.0)
9.7 (+2.8)
69.7 (+57.2)
83.3 (+51.4)
16.7 (+5.6)
11.6 (+5.0)
68.4 (+59.3)
15.1 (+2.3)
16.9 (+7.7)
0.0 (-388.7)
8.3 (-57.8)
7.5 (+2.1)
9.3 (-167.3)
Appendix
Table 5: Performance comparison between the baseline model (Wan2.2-TI2V-5B), task-specific Wan-SFT models, and our method across four game types: Base, Irreg, 3D, and Soko. Each cell displays the absolute performance alongside the relative change from the baseline across four metrics (EM, SR, PR, SD).
Task
EM
SR
PR
SD
Raw
Sk2
Sk3
Raw
Sk2
Sk3
Raw
Sk2
Sk3
Raw
Sk2
Sk3
Base
Base
0.0
0.0
0.0
6.9
4.2
2.8
6.6
4.6
9.4
388.7
11.7
14.9
SFT
33.3
1.4
23.6
76.4
38.9
68.1
60.6
12.3
51.0
10.3
19.0
9.0
R1
61.1
31.9
31.9
75.0
70.8
70.8
78.6
52.5
52.5
5.2
27.1
27.1
Δ
+61.1
+31.9
+31.9
+68.1
+66.6
+68.0
+72.0
+47.9
+43.1
-383.5
+15.4
+12.2
Irreg
Base
0.0
0.0
0.0
12.5
4.2
2.1
9.1
12.0
47.8
66.1
39.5
42.0
Appendix
Table 6: Texture generalization performance across different visual skins. For each task, we report the baseline (Base), Wan-SFT , and Wan-R1 across three texture conditions (Raw, Sk2=Skin2, Sk3=Skin3), with Δ indicating Wan-R1 improvement over baseline. See texture sample in Figure 7 .
Method
MF ( ↑ )
Base
Irreg
Trap
3D
Soko
General Video Model
Closed-Source
Veo-3.1-fast
43.2
86.3
22.5
69.1
63.5
Veo-3.1-pro
80.5
89.3
82.2
73.4
95.8
Sora-2
96.5
97.2
97.2
95.4
95.2
kling-v1
55.5
73.8
54.4
84.9
72.9
Appendix
Table 7: MF denotes Maze Fidelity.
Table 8: Ablation studies on cold start (left) and reward models (right).
Figure 4: Test-time scaling performance of Wan-R1 on Irregular Maze tasks. Performance is evaluated across varying numbers of samples ( K∈{1,4,8,12,16} ) and three difficulty levels (Easy, Medium, Hard). RL improves base capability (K=1) while maintaining beneficial scaling with increased sampling.
Figure 5: Given the video output along with the evaluation prompt describing maze-solving rules, Qwen2.5-VL-7B-Instruct produces a step-by-step analysis and assigns a reward score. Although the generated video exhibits visible glitches and degraded visual quality, the model assigns a perfect score of 1.0. This illustrates the core vulnerability of VLM-based reward models: rather than detecting actual visual artifacts, the model hallucinates quality based on high-level semantic cues—a visible agent, a recognizable maze structure, and apparent goal-directed motion—and incorrectly concludes that the video contains “no glitches, noise, or artifacts.”
Figure 6: Trajectory tracking across five maze types (This figure is from [ 45 ] ). Green: ground-truth trajectory; Blue: tracked trajectory from generated video. Columns show temporally ordered frames illustrating agent motion over time.
Figure 7: Overview of VR-Bench (This figure is from VR-Bench [ 45 ] ) (A) Maze Types: Five maze types—Regular, Irregular, 3D, Trapfield, and Sokoban—spanning 2D/3D settings and diverse task structures. (B) Reasoning Paradigm: Chain-of-frame reasoning [ 40 ] requiring frame-by-frame inferences for sequential visual reasoning. (C) Benchmark Performance: Leading VLMs evaluated on four metrics across all maze types. (D) Additional Analysis: Evaluations on difficulty, texture, and maze-type generalization, plus test-time scaling.
Figure 8: Overview of Target-Bench (This figure is from Target-Bench [ 37 ] ). Target-Bench introduces a quadruped-robot dataset and benchmark for assessing world models in mapless navigation toward text-specified goals with implicit semantic content. Given a single camera frame and a natural language description of the desired target state, world models must synthesize a future video depicting the trajectory to that goal. A world decoder then recovers the planned path from the generated video, which is evaluated against ground-truth maneuvers collected from a human-operated quadruped.
Video diffusion models have made rapid progress in perceptual realism and temporal coherence, but they remain primarily optimized for plausible generation rather than verifiable reasoning. This limitation is especially pronounced in tasks where generated videos must satisfy explicit spatial, temporal, or logical constraints. Inspired by the role of reinforcement learning with verifiable rewards (RLVR) in reasoning-oriented language models, we introduce VideoRLVR, a practical recipe for optimizing video diffusion models with rule-based feedback. VideoRLVR formulates video reasoning as the generation of verifiable visual trajectories and consists of an SDE-GRPO optimization backbone, dense decomposed rewards, and an Early-Step Focus strategy for efficient training. The Early-Step Focus strategy restricts policy optimization to the early denoising phase, reducing training latency by about 40% while preserving performance. We evaluate VideoRLVR on Maze, FlowFree, and Sokoban, three procedurally generated domains with objective success criteria. Across these tasks, VideoRLVR consistently improves over supervised fine-tuning baselines, with dense decomposed rewards proving especially important in low-success-rate settings. Our RL-optimized model also outperforms the evaluated proprietary and open-source video generation models on these verifiable reasoning benchmarks and out-of-domain benchmarks. These results suggest that verifiable RL can move video models beyond perceptual imitation toward more reliable rule-consistent visual reasoning.
Tinghui Zhu, Sheng Zhang, James Y. Huang +5
University of California, Davis · Microsoft Research · University of Southern California +1
Video reasoning has advanced with large multimodal models (LMMs), yet their inference is often a single pass that returns an answer without verifying whether the reasoning is evidence-aligned. We introduce Reinforce to Learn, Elect to Reason (RLER), a dual paradigm that decouples learning to produce evidence from obtaining a reliable answer. In RLER-Training, we optimize the policy with group-relative reinforcement learning (RL) and 3 novel task-driven rewards: Frame-sensitive reward grounds reasoning on explicit key frames, Think-transparency reward shapes readable and parsable reasoning traces, and Anti-repetition reward boosts information density. These signals teach the model to emit structured, machine-checkable evidence and potentiate reasoning capabilities. In RLER-Inference, we apply a train-free orchestrator that generates a small set of diverse candidates, parses their answers and cited frames, scores them by evidence consistency, confidence, transparency, and non-redundancy, and then performs a robust evidence-weighted election. This closes the loop between producing and using evidence, improving reliability and interpretability without enlarging the model. We comprehensively evaluate RLER against various open-source and RL-based LMMs on 8 representative benchmarks. RLER achieves state of the art across all benchmarks and delivers an average improvement of 6.3% over base models, while using on average 3.1 candidates per question, indicating a favorable balance between compute and quality. The results support a simple thesis: making evidence explicit during learning and electing by evidence during inference is a robust path to trustworthy video reasoning.
Songyuan Yang, Weijiang Yu, Jilin Ma +5
National University of Defense Technology · Sun Yat-sen University
Video reasoning requires models to locate and track question-relevant evidence across frames. While reinforcement learning (RL) with verifiable rewards improves accuracy, it still struggles to achieve reliable spatio-temporal grounding during the reasoning process. Moreover, improving grounding typically relies on scaled training data or inference-time perception tools, which increases annotation cost or computational cost. To address this challenge, we propose VisonCoach, an input-adaptive RL framework that improves spatio-temporal grounding through visual prompting as training-time guidance. During RL training, visual prompts are selectively applied to challenging inputs to amplify question-relevant evidence and suppress distractors. The model then internalizes these improvements through self-distillation, enabling grounded reasoning directly on raw videos without visual prompting at inference. VisonCoach consists of two components: (1) Visual Prompt Selector, which predicts appropriate prompt types conditioned on the video and question, and (2) Spatio-Temporal Reasoner, optimized with RL under visual prompt guidance and object-aware grounding rewards that enforce object identity consistency and multi-region bounding-box overlap. Extensive experiments demonstrate that VisonCoach achieves state-of-the-art performance under comparable settings, across diverse video reasoning, video understanding, and temporal grounding benchmarks (V-STAR, VideoMME, World-Sense, VideoMMMU, PerceptionTest, and Charades-STA), while maintaining a single efficient inference pathway without external tools. Our results show that visual prompting during training improves grounded video reasoning, while self-distillation enables the model to internalize this ability without requiring prompts at inference time.