Multimodal Sentiment Analysis (MSA) is a popular research topic aimed at utilizing multimodal signals for understanding human emotions. The primary approach to solving this task is to develop complex fusion techniques. However, the heterogeneity and unaligned nature between modalities pose significant challenges to fusion. Additionally, existing methods lack consideration for the efficiency of modal fusion. To tackle these issues, we propose AcFormer, which contains two core ingredients: i) contrastive learning within and across modalities to explicitly align different modality streams before fusion; and ii) pivot attention for multimodal interaction/fusion. The former encourages positive triplets of image-audio-text to have similar representations in contrast to negative ones. The latter introduces attention pivots that can serve as cross-modal information bridges and limit cross-modal attention to a certain number of fusion pivot tokens. We evaluate AcFormer on multiple MSA tasks, including multimodal emotion recognition, humor detection, and sarcasm detection. Empirical evidence shows that AcFormer achieves the optimal performance with minimal computation cost compared to previous state-of-the-art methods. Our code is publicly available at https://github.com/dingchaoyue/AcFormer.

In this paper, we present the solutions to the MER-MULTI and MER-NOISE sub-challenges of the Multimodal Emotion Recognition Challenge (MER 2023). For the tasks MER-MULTI and MER-NOISE, participants are required to recognize both discrete and dimensional emotions. Particularly, in MER-NOISE, the test videos are corrupted with noise, necessitating the consideration of modality robustness. Our empirical findings indicate that different modalities contribute differently to the tasks, with a significant impact from the audio and visual modalities, while the text modality plays a weaker role in emotion prediction. To facilitate subsequent multimodal fusion, and considering that language information is implicitly embedded in large pre-trained speech models, we have made the deliberate choice to abandon the text modality and solely utilize visual and acoustic modalities for these sub-challenges. To address the potential underfitting of individual modalities during multimodal training, we propose to jointly train all modalities via a weighted blending of supervision signals. Furthermore, to enhance the robustness of our model, we employ a range of data augmentation techniques at the image level, waveform level, and spectrogram level. Experimental results show that our model ranks 1st in both MER-MULTI (0.7005) and MER-NOISE (0.6846) sub-challenges, validating the effectiveness of our method. Our code is publicly available at https://github.com/dingchaoyue/Multimodal-Emotion-Recognition-MER-and-MuSe-2023-Challenges.