Abstract
A fundamental issue in understanding visual object perception is how we are able to select and attend to individual objects in the environment. One relevant source of evidence has come from studies of inhibition of return (IOR). With this paradigm, it has been shown that detection latencies can be longer for targets presented on previously attended, rather than on unattended, objects independently of their spatial location. This finding has been taken as evidence for the existence of an object-based selection mechanism. The present study describes a new empirical observation showing that the magnitude of object-based IOR can be modulated by object-internal structure. We show that structure-based modulation arises at a level of shape representation that makes explicit surface, but not volumetric, part structure. Furthermore, this structure-based modulation effect occurs at a level of shape representation computed after preattentive image segmentation.