From Cause to Effect: Generating Intermediate Event Chains in Videos

Ridouane Ghermi, Vicky Kalogeiton, Ivan Laptev


Abstract
Video-Language Models (VLMs) excel at visual recognition but struggle with causal reasoning. Current evaluations are flawed: multiple-choice QA allows shortcuts, and open-ended QA lacks robust automatic evaluation. We introduce Causal Chain Generation (CCG), a novel task where models have to generate the sequence of intermediate events connecting a cause and an effect. This structured setup demands genuine reasoning and enables reliable automatic scoring. We accompany this task with two complementary metrics: SODA-Embedding, which measures the semantic matching of a generated chain against a reference, and Causal-QA, which probes the chain’s causal coherence by asking whether it contains the specific causal facts needed to reconstruct the narrative. We provide two test sets: SF20K-CC, a manually annotated diagnostic on 20 short films, and CMD-CC, a movie clip benchmark derived from audio descriptions. Our analysis reveals that state-of-the-art VLMs struggle with narrative causality understanding, frequently hallucinating or omitting key events. To address this, we fine-tune VLMs with GRPO using a composite reward that combines a format reward, SODA-Embedding, and Causal-QA accuracy, demonstrating substantial improvements over strong baselines.
Anthology ID:
2026.emnlp-main.2498
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
56724–56746
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2498/
DOI:
Bibkey:
Cite (ACL):
Ridouane Ghermi, Vicky Kalogeiton, and Ivan Laptev. 2026. From Cause to Effect: Generating Intermediate Event Chains in Videos. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 56724–56746, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
From Cause to Effect: Generating Intermediate Event Chains in Videos (Ghermi et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2498.pdf