ISO-Bench: Benchmarking Multimodal Causal Reasoning in Visual–Language Models through Procedural Plans

Ananya Sadana, Yash Kumar Lal, Jiawei Zhou


Abstract
Understanding causal relationships across modalities is a core challenge for multimodal models operating in real-world environments. We introduce ISO-Bench, a benchmark for evaluating whether models can infer causal dependencies between visual observations and procedural text. Each example presents an image of a task step and a text snippet from a plan, with the goal of deciding whether the visual step occurs before or after the referenced text step. Evaluation results on ten frontier vision-language models show underwhelming performance: the best zero-shot F1 is only 0.57, and chain-of-thought reasoning yields only modest gains (up to 0.62 F1), largely behind humans (0.98 F1). Our analysis further highlights concrete directions for improving causal understanding in multimodal models.
Anthology ID:
2026.gem-main.68
Volume:
Proceedings of the Fifth Workshop on Generation, Evaluation and Metrics (GEM)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Simon Mille, Sebastian Gehrmann, Patrícia Schmidtová, Ondřej Dušek, Marzieh Fadaee, Kyle Lo, Enrico Santus, Gabriel Stanovsky
Venues:
GEM | WS
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Publisher:
Association for Computational Linguistics
Note:
Pages:
797–807
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.gem-main.68/
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Cite (ACL):
Ananya Sadana, Yash Kumar Lal, and Jiawei Zhou. 2026. ISO-Bench: Benchmarking Multimodal Causal Reasoning in Visual–Language Models through Procedural Plans. In Proceedings of the Fifth Workshop on Generation, Evaluation and Metrics (GEM), pages 797–807, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
ISO-Bench: Benchmarking Multimodal Causal Reasoning in Visual–Language Models through Procedural Plans (Sadana et al., GEM 2026)
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https://preview.aclanthology.org/ingest-acl-workshops/2026.gem-main.68.pdf