  Multimodal learning mimics the reasoning process of the human multi-sensory
system, which is used to perceive the surrounding world. While making a
prediction, the human brain tends to relate crucial cues from multiple sources
of information. In this work, we propose a novel multimodal fusion module that
learns to emphasize more contributive features across all modalities.
Specifically, the proposed Multimodal Split Attention Fusion (MSAF) module
splits each modality into channel-wise equal feature blocks and creates a joint
representation that is used to generate soft attention for each channel across
the feature blocks. Further, the MSAF module is designed to be compatible with
features of various spatial dimensions and sequence lengths, suitable for both
CNNs and RNNs. Thus, MSAF can be easily added to fuse features of any unimodal
networks and utilize existing pretrained unimodal model weights. To demonstrate
the effectiveness of our fusion module, we design three multimodal networks
with MSAF for emotion recognition, sentiment analysis, and action recognition
tasks. Our approach achieves competitive results in each task and outperforms
other application-specific networks and multimodal fusion benchmarks.
