Abstract
Selective attention influences not only which objects in a display are perceived, but also directly changes the character of how they are perceived—for example making attended objects appear larger or brighter. Here we explore the influence of sustained selective attention on where objects are perceived in relation to each other, in dynamic multi-object displays. Surprisingly, we find that sustained attention warps perceived space in a way that is object-specific: space between targets is perceptually compressed, while space between distractors is perceptually expanded. In an initial multiple object tracking (MOT) task, observers tracked two targets among two distractors. At the end of each trial, however, observers did not click on the target objects, as in typical MOT tasks. Instead, the entire display disappeared, and subjects simply indicated the last perceived location of each object (responding for targets first, followed by distractors). Beyond global spatial compression for the display as a whole, perceived target locations were reported as closer to each other than were perceived distractor locations, in a way that could not be explained by appeal to the response order. We also found similar (and even stronger) object-specific compression effects in a task that did not involve MOT, but simply required sustained monitoring for brief probes in dynamic displays. These effects were specific to targets and distractors per se: factoring out baseline compression toward the center of the display, attended objects seemed to attract each other, while inhibited objects seemed to repel each other. These effects suggest that sustained attention warps perceived space in unexpected ways, and in a manner distinct from previously studied effects of transient attentional shifts.