Adaptive Hierarchical Representation Alliance for Multimodal Learning

Chunlei Meng, Pengbin Feng, Jacqueline J. Pang, Chih-Ting Liao, Rong Fu, Zhaolu Kang, Zhongxue Gan, Chun Ouyang


Abstract
Multimodal models often align language, vision, and audio in a single final-layer latent space, implicitly assuming that task-relevant evidence emerges at the same semantic depth across modalities. Using layer-wise CKA analysis, we observe that this assumption leads to semantic granularity mismatch: textual cues usually require deeper contextual abstraction, whereas visual and acoustic cues often provide discriminative perceptual evidence in shallow or middle layers. This mismatch can flatten fine-grained modality-private cues and reduce reliability under noisy, imbalanced, or missing inputs. To address this, we proposed Adaptive Hierarchical Representation Alliance (AHRA), a hierarchical shared–private expert framework. AHRA factorizes each modality into shared and private streams across semantic levels, regularizes them with shared alignment and private decorrelation, routes shared information through a cross-modal expert, and enhances task-relevant private tokens with modality-specific experts guided by a sparsity-controlled soft-gating mechanism (foreground exam). A hierarchical co-fusion module then performs intra-level expert coordination and inter-level semantic selection. Experiments on six benchmarks across image-text classification, multimodal intent recognition, and trimodal sentiment analysis show that AHRA consistently improves over strong baselines and remains robust under noisy and missing-modality settings.
Anthology ID:
2026.findings-emnlp.1014
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:
21423–21439
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URL:
https://aclanthology.org/2026.findings-emnlp.1014/
DOI:
Bibkey:
Cite (ACL):
Chunlei Meng, Pengbin Feng, Jacqueline J. Pang, Chih-Ting Liao, Rong Fu, Zhaolu Kang, Zhongxue Gan, and Chun Ouyang. 2026. Adaptive Hierarchical Representation Alliance for Multimodal Learning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 21423–21439, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Adaptive Hierarchical Representation Alliance for Multimodal Learning (Meng et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1014.pdf