Hierarchical Concept Bottleneck With Compensation Concept Learning

Concept Bottleneck Models (CBMs) enhance the interpretability of deep neural networks by mapping images to human-understandable concepts and then using the concepts to make predictions. While they improve transparency, existing CBMs primarily explain only the final layer's features, limiting the interpretability of intermediate layers. Additionally, constructing a comprehensive concept set remains a challenging task, further constraining model performance. In this paper, we investigate the assignment of concept granularity across model layers and propose the Hierarchical Concept Bottleneck Model (HCBM) to enhance interpretability. HCBM introduces a Hybrid Concept Bottleneck Layer (HCBL) at each layer, consisting of a Predefined Concept Bottleneck (PCB) that maps visual features to concepts of corresponding granularity and a Compensation Concept Bottleneck (CCB) which incorporates the concept frequency loss and the concept semantic loss to capture compensation concepts for improving performance. Extensive experiments demonstrate that HCBM outperforms state-of-the-art methods. It is worth noting that the HCBM with CLIP RN50 as the backbone outperforms the black-box model.