Invariant Meets Specific: A Scalable Harmful Memes Detection Framework

Harmful memes detection is a challenging task in the field of multimodal information processing due to the semantic gap between different modalities. Current research on this task mainly focuses on multimodal dual-stream models. However, the existing works ignore the misalignment of the memes caused by the modality gap. Moreover, the cross-modal interaction in the dual-stream models is insufficient to identify harmful memes. To this end, this paper proposes a scalable invariant and specific modality (ISM) representations framework via graph neural networks. The proposed ISM framework provides a comprehensive and disentangled view for memes and promotes inter-modal interaction. Specifically, ISM projects each modality to two distinct spaces. The first space is modality-invariant, learning the corresponding commonalities and reducing the modality gap. The second space is modality-specific, holding the distinctive characteristics of each modality and complementing the common latent features captured in invariant spaces. Then, we construct fully connected visual and textual graphs for each space. The unimodal graphs are fused to dynamically balance inter-modal and intra-modal relationships, which are complementary to the dual-stream models. Finally, an adaptive module is designed to weigh the proportion of each fusion graph for memes. Moreover, the mainstream multimodal dual-stream models could be employed as the backbone flexibly. Extensive experiments on five publicly available datasets show that the proposed ISM provides a stable improvement over baselines and produces a competitive performance compared with the existing harmful memes detection methods.