Detecting Social Bot on the Fly using Contrastive Learning

Abstract

Social bot detection is becoming a task of wide concern in social security. All along, the development of social bot detection technology is hindered by the lack of high-quality annotated data. Besides, the rapid development of AI Generated Content (AIGC) technology is dramatically improving the creative ability of social bots. For example, the recently released ChatGPT [2] can fool the state-of-the-art AI-text-detection method with a probability of 74%, bringing a large challenge to content-based bot detection methods. To address the above drawbacks, we propose a Contrastive Learning-driven Social Bot Detection framework (CBD). The core of CBD is characterized by a two-stage model learning strategy: a contrastive pre-training stage to mine generalization patterns from massive unlabeled social graphs, followed by a semi-supervised fine-tuning stage to model task-specific knowledge latent in social graphs with a few annotations. The above strategy endows our model with promising detection performance under an extreme scarcity of labeled data. In terms of system architecture, we propose a smart feedback mechanism to further improve detection performance. Comprehensive experiments on a real bot detection dataset show that CBD consistently outperforms 10 state-of-the-art baselines by a large margin for few-shot bot detection using very little (5-shot) labeled data. CBD has been deployed online.