Deep Information-Balanced Multimodal Learning

Multimodal learning aims to integrate diverse data sources to capture more comprehensive information about things, thus enhancing perception and understanding of the real world. However, inherent discrepancies between different modalities often lead to imbalanced optimization during multimodal learning, hindering performance improvement. To address this issue, in this paper, we present a Multimodal Information Balance (MIB) theory, grounded in Information Theory, to reveal that this imbalance arises from the imbalanced retention of complementary information during modality fusion, providing an intuitive and explainable perspective on the issue. Building on this insight, we propose a theoretical MIB criterion to adaptively balance the preservation of complementary information across individual modalities, thereby facilitating multimodal fusion. Using this criterion, we develop an Information-Balanced Multimodal Learning (IBML) framework to mine comprehensive and balanced multimodal information, achieving optimal learning. More specifically, IBML introduces Balance Information Optimization (BIO) module to maximize tractable lower bound objectives derived from the MIB criterion according to the optimization discrepancies across modalities, ensuring balanced retention of complementary information and enhancing information contributions during multimodal fusion. In addition, we present a supplementary and provable Task Complexity Modulation (TCM) module based on the MIB criterion to adjust task complexity discrepancies across input modalities, thus indirectly promoting the balanced preservation of complementary information throughout the learning process. Extensive experiments are conducted on eight multimodal datasets, spanning audio-visual recognition, image-text classification, and 2D-3D recognition, to verify the superiority and effectiveness of IBML.