Proposed structure of memory representations in both simple and real-world displays. (a) In simple displays of meaningless shapes, information is represented both at the item level (perhaps as a hierarchical feature-bundle), and across individual items at the ensemble level. (b) Real world displays have information represented at the object level (as a hierarchical feature bundle), and at the scene level (including scene statistics computed over basic features). In both simple and real-world displays, information is represented at the individual item level, and across individual items, possibly in parallel but interacting processing streams.