MMDS-Bench: Benchmarking Multimodal Large Language Models on Dynamic Stance in Social Media Interactions

Yuzhe Ding, Kang He, Li Zheng, Shengwu Zheng, Teng Shi, Fei Li, Chong Teng, Donghong Ji


Abstract
Dynamic stance classification models how a reply responds to its direct parent message, rather than how a post relates to a fixed topic. Existing work has mainly studied this problem in text-only settings, while social media interactions increasingly rely on images, screenshots, memes, reaction images, and cross-modal references. We introduce MMDS-Bench, a diagnostic benchmark for multimodal dynamic stance classification in social media parent–reply interactions. MMDS-Bench contains 3,482 multimodal instances annotated with a seven-label dynamic stance taxonomy, together with an 800-instance diagnostic subset that requires structured reasoning over parent understanding, reply understanding, and stance-relation inference. We further annotate each instance with five challenge factors covering multimodal fusion, parent framing, non-literal expression, interaction reasoning, and label-boundary ambiguity. We evaluate 12 closed-source and open-source multimodal large language models and propose a reference-grounded LLM-judge protocol for assessing reasoning quality. Results show that current MLLMs still struggle with multimodal dynamic stance understanding, especially in cases that require relational inference beyond separate parent and reply comprehension.
Anthology ID:
2026.emnlp-main.1165
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:
26646–26667
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1165/
DOI:
Bibkey:
Cite (ACL):
Yuzhe Ding, Kang He, Li Zheng, Shengwu Zheng, Teng Shi, Fei Li, Chong Teng, and Donghong Ji. 2026. MMDS-Bench: Benchmarking Multimodal Large Language Models on Dynamic Stance in Social Media Interactions. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 26646–26667, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MMDS-Bench: Benchmarking Multimodal Large Language Models on Dynamic Stance in Social Media Interactions (Ding et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1165.pdf