SourceA Theoretical Analysis of Self-Supervised Learning for Vision Transformers
Using a novel attention diversity metric that measures whether different query patches concentrate on similar or distinct regions, the authors compare the last-layer attention of four ViT-B/16 encoders pretrained on ImageNet-1k. Across 12 attention heads and 152 example images, the MAE-pretrained model shows substantially higher diversity (attention dispersed across different local areas), while MoCo v3, DINO, and DeiT all show lower diversity (attention collapsed toward a common global region). This empirically confirms the theoretical prediction that masked reconstruction preserves local attention patterns while discriminative objectives collapse to global ones.