Spatiotemporal characteristics of dynamic feature binding in visual working memory.

It has been proposed that visual working memory can hold a set of four to five coherent object representations. As a test of this proposal, I devised a paradigm called multiple object permanence tracking (MOPT) that measures memory for feature-location binding in dynamic situations. Observers were asked to detect any feature switch in the middle of a regular rotation of a pattern with multiple objects behind an occluder. The feature switch detection performance dramatically declined as the pattern rotation velocity increased. The behavioral evidence for the use of multiple color-shape conjunction was observed only when the objects were stationary. These results cast doubt on the view that the functional unit of visual working memory involves coherent object representation, where object features are tightly bound and dynamically updated.