Multimodal sarcasm detection is a complex task that requires distinguishing subtle complementary signals across modalities while filtering out irrelevant information. Many advanced methods rely on learning shortcuts from datasets rather than extracting intended sarcasm-related features. However, our experiments show that shortcut learning impairs the model's generalization in real-world scenarios. Furthermore, we reveal the weaknesses of current modality fusion strategies for multimodal sarcasm detection through systematic experiments, highlighting the necessity of focusing on effective modality fusion for complex emotion recognition. To address these challenges, we construct MUStARD++R by removing shortcut signals from MUStARD++. Then, a Multimodal Conditional Information Bottleneck (MCIB) model is introduced to enable efficient multimodal fusion for sarcasm detection. Experimental results show that the MCIB achieves the best performance without relying on shortcut learning.

The social relation is a fundamental attribute of human beings in daily life. The ability of humans to form large organizations and institutions stems directly from our complex social networks. Therefore, understanding social relationships in the context of multimedia is crucial for building domain-specific or general artificial intelligence systems. The key to reason social relations lies in understanding the human interactions between individuals through multimodal representations such as action and utterance. However, due to video editing techniques and various narrative sequences in videos, two individuals with social relationships may not appear together in the same frame or clip. Additionally, social relations may manifest in different levels of granularity in video expressions. Previous research has not effectively addressed these challenges. Therefore, this paper proposes aMulti-Granularity Relation Graph Aggregation Framework(MGRG) to enhance the inference ability for social relation reasoning in multimedia content, like video. Different from existing methods, our method considers the paradigm of jointly inferring the relations by constructing a social relation graph. We design a hierarchical multimodal relation graph illustrating the exchange of information between individuals' roles, capturing the complex interactions at multi-levels of granularity from fine to coarse. In MGRG, we propose two aggregation modules to cluster multimodal features in different granularity layer relation graph, considering temporal aspects and importance. Experimental results show that our method generates a logical and coherent social relation graph and improves the performance in accuracy.

Traditional dense video captioning predominantly focuses on edited exocentric footage. These videos are filmed from an external perspective and generally feature distinct transitions between different events, as exemplified in edited instructional videos. However, such videos do not genuinely reflect the way we perceive our real lives. Instead, we observe the world from an egocentric viewpoint and witness only continuous unedited footage. To facilitate further research, we introduce a new topic: Egocentric Vehicle Dense Video Captioning, in classic vehicle driving scenarios. This is a multi-modal, multi-task subject endeavor for a comprehensive understanding of untrimmed, egocentric driving videos. It consists of three sub-tasks that concentrate on event localization, captioning, and vehicle state estimation separately. To accomplish these tasks, it is necessary to deal with at least three challenges: extracting ego-motion relevant information, describing driving behavior and analyzing the underlying rationale, as well as resolving the boundary ambiguity problem. In response, we devise corresponding solutions, including a vehicle ego-motion learning strategy and a novel adjacent contrastive learning strategy, which effectively address the aforementioned issues. We validate our method by conducting extensive experiments on the BDD-X dataset, all of which show promising results and achieve new state-of-the-art performance on most metrics, which proves the effect of our approach.