Differential Boundary-Shape Effects on Visual Working Memory Suggests Encoding Formats Evolve from Early Perception to Statistical Compression

Visual working memory showed striking temporal dissociation: angular boundaries (rectangles, pentagons) enhanced early maintenance (500ms) but declined 40%+, while circular boundaries improved 130% by 1500ms, achieving >100% efficiency. Performance changes followed geometric principles (R²=.93). Findings reveal dynamic memory reorganization from discrete perceptual to statistical ensemble representations, reconciling competing capacity theories.