Abstract
Visual working memory is highly sensitive to global configurations in addition to features of each individual object. When objects are moving, their configuration varies correspondingly. Here we explore the geometric rules governing the maintenance of such a dynamic configuration in visual working memory. Our investigation is guided by the Erlangen program, which is a hierarchy of geometric stability, including affine, projective and topological invariants. The configuration here was defined as the virtual polygon with the four dots being its vertices. In all cases, the boundary of the virtual polygon overlapped with the convex hull of the four dots. The shape of the virtual polygon was gradually transformed to a new one by the motion of each dot in the memory display. In a change detection task, this memory displays were categorized by which geometry invariance was violated by the objects' motions. The results show that (a) there was no decrement of memory performance until the projective invariance was violated; (b) more dramatic changes (such as a topological change) cannot further enlarge the decrement; (c) objects causing the violation of projective invariance were better encoded in memory. These results collectively demonstrate that projective invariance is the only geometric property determining the maintenance of a dynamic configuration in visual working memory. （Acknowledgement: This research is supported by the National Natural Science Foundation of China (No. 31170974; 31170975).）
Meeting abstract presented at VSS 2015