A Survey on Deep Learning for Group-Level Emotion Recognition

With the rapid advancement of artificial intelligence, group-level emotion recognition (GER) has emerged as an important domain in human behavior analysis. Early GER methods primarily relied on handcrafted features. However, the recent success of deep learning has shifted the focus toward neural network-based solution, enabling more effective exploitation of the rich visual and contextual cues in group images and videos. Unlike individual-level emotion recognition, GER must account for the diversity and dynamics of multiple individuals within varied social contexts. Over the past decade, numerous deep learning-based methods have been proposed, achieving substantial performance gains. This survey provides a comprehensive review of deep learning-centric review of GER, introducing a new taxonomy that spans representation learning, graph-based modeling, attention and transformer architectures, and multimodal fusion strategies. We summarize benchmark datasets, outline prevailing GER pipelines, and consolidate performance trends from recent state-of-the-art approaches. In addition, we discuss the integration of foundation models and large language model-guided multimodal reasoning into GER. Key challenges are identified, and potential research directions are proposed to support the development of robust, real-world GER systems. This work aims to serve as a pivotal reference for future research in this evolving field.