Abstract
Object-based attention (OBA) leads to preferential processing of visual information contained in/on an attended versus unattended object. We recently demonstrated that attention shifts across the visual field meridians resulted in faster reallocation of OBA horizontally than vertically (Shift Direction Anisotropy, SDA; Barnas & Greenberg, AP&P, 2016), suggesting a modulatory role of the meridians on OBA reorienting. Here, we aimed to determine whether the observed SDA caused by the visual field meridians depends upon the locations of targets, objects, or both. In three experiments, we utilized an 'L'-shaped object comprised of a horizontal rectangle fused to a vertical rectangle. Following a partially valid peripheral cue, participants detected the presence of a target at a cued location (valid condition) or at one of two noncued locations equidistant from the cue in either the horizontal (invalid-horizontal condition) or vertical (invalid-vertical condition) object component. For each experiment, we manipulated object and target location across the meridians (relative to the cued location) such that: (a) both object ends and targets either crossed the meridians or did not cross the meridians (Experiment 1), (b) object ends always crossed the meridians, but targets either crossed or did not cross the meridians (Experiment 2), and (c) targets never crossed the meridians, but object ends either crossed or did not cross the meridians (Experiment 3). Across all three experiments, the SDA emerged only when target location necessitated shifts of object-based attention that crossed the meridians. When target location did not necessitate shifts of attention that crossed the meridians, we observed no SDA, regardless of object location. These results demonstrate that the SDA is driven by target location, rather than object location, relative to visual field meridians, hence suggesting that OBA processes serve to prioritize specific target locations and not simply all locations within a cued object.
Meeting abstract presented at VSS 2017