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Adam Barnas, Adam Greenberg; Object-Based Attention Shift Direction Efficiency: Behavior and a Model. Journal of Vision 2016;16(12):699. doi: 10.1167/16.12.699.
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© 2017 Association for Research in Vision and Ophthalmology.
Object-based attention (OBA) leads to preferential processing within the boundaries of a selected object. Pilz and colleagues (2012) demonstrated larger OBA effects for horizontal rectangles than vertical rectangles; these effects were eliminated when controlling for attention shifts across the visual field meridians (Greenberg et al., 2014). We recently showed that reallocation of OBA is faster horizontally than vertically (Barnas & Geenberg, 2015) when objects cross the meridians. The RT difference between horizontal and vertical shifts (Shift Direction Difference; SDD) was larger for uncued objects (~120ms) than cued objects (~80ms). Here, we aimed to further elucidate the modulatory role of the visual field meridians on OBA and to model the underlying components contributing to the SDD. In three experiments, we utilized an 'L'-shaped object comprised of a horizontal rectangle hinged to a vertical rectangle, sequestered into one screen quadrant. Following a partially valid peripheral cue, participants detected the presence of a target at a cued location (valid condition) or at one of two uncued locations (invalid conditions) equidistant from the cue in either the horizontal or vertical object component. SDD magnitude was significant when the cued object was near fixation (62ms), but not when the cued object was far from fixation (20ms). Based on these findings, in another experiment we accurately predicted SDD magnitudes for uncued objects near and far from fixation as 102 and 41 ms, respectively. Our behavioral results led to a model of SDD magnitude that incorporates effects of meridian crossings (horizontal vs vertical; ~40ms), object selection (cued vs uncued; ~40ms), and object vertex location (near vs far from fixation; ~60ms). Taken together, our findings necessitate updating current OBA theories to include effects of these three parameters, which seem to account for the often-reported difference in OBA shift direction efficiency between horizontally and vertically oriented objects.
Meeting abstract presented at VSS 2016
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