Diagnosing and Selecting Synthetic Motion Tasks for Video RLVR

Yishu Lei, Aofan Liu, Danxiang Zhu, Canming Ye, Dan Zhang, Songhe Deng, Xianlong Luo, Shikun Feng


Abstract
Synthetic video data with verifiable rewards offers a scalable source of supervision for temporal motion understanding in video-language models, yet it remains unclear which synthetic tasks transfer reliably to real-video benchmarks.We investigate this question through a diagnostic framework that treats each synthetic task as a controlled intervention.Starting from a shared Qwen3-VL-2B checkpoint with frozen vision encoder, we independently train nine programmatic motion tasks with RLVR and evaluate each resulting model across six temporal-motion dimensions, such as direction, rotation, and velocity, yielding an interference matrix of cross-dimensional transfer. The matrix reveals substantial variation in transfer that surface-level label alignment fails to explain: a frame-to-frame velocity task yields a large gain on its target dimension, whereas a nominally aligned trajectory-shape task degrades the dimension it is intended to improve. We find that transfer is better explained by computational alignment, namely whether the training task induces the local, order-sensitive temporal computation that the downstream capability requires.Counterfactual tasks that share semantic targets but differ in computational demands support this account, and the patterns hold on InternVL3-2B. We further introduce a training-free answer-invariance test under frame shuffling that flags shortcut-prone tasks prior to RLVR training. Using the interference matrix to filter tasks yields a task mixture that consistently outperforms uniform mixing on TOMATO, with positive transfer trends on MVBench, TempCompass, and TemporalBench.Our framework thus reframes synthetic video generation as an empirically grounded task-selection problem.
Anthology ID:
2026.findings-emnlp.1176
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
24858–24871
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1176/
DOI:
Bibkey:
Cite (ACL):
Yishu Lei, Aofan Liu, Danxiang Zhu, Canming Ye, Dan Zhang, Songhe Deng, Xianlong Luo, and Shikun Feng. 2026. Diagnosing and Selecting Synthetic Motion Tasks for Video RLVR. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 24858–24871, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Diagnosing and Selecting Synthetic Motion Tasks for Video RLVR (Lei et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1176.pdf