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Dwight J. Kravitz, Marlene Behrmann; Object-based attentional selection modulates the spatial gradient surrounding the object. Journal of Vision 2005;5(8):1036. doi: 10.1167/5.8.1036.
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© ARVO (1962-2015); The Authors (2016-present)
Many theories of object-based attention implicitly assume that the facilitation is limited to locations within the borders of the attended object and fail to address the attentional consequences for locations surrounding the object. In a series of experiments utilizing standard object-based target detection and discrimination paradigms, we show that the object as a whole, and in particular distance from its center of mass, is critical in determining the facilitation of locations in the surround. First, we compared detection times to two invalid targets, equidistant from the cue, which appeared in the space surrounding a cued object. Interestingly, the target closer to the object's center of mass was detected faster and this advantage held across several object locations and orientations. By probing targets at systematically varying distances we established that the facilitation of targets in the surround is a linear function of distance from the object's center of mass. Finally, we directly manipulated the center of mass while holding all target locations constant, demonstrating that discrimination times for these targets was dependent on distance from the center of mass. Taken together these results indicate a close coupling between space- and object-based attention, whereby attending to an object has implications for the spatial distribution of attentional facilitation throughout the scene. These results are consistent with a distributed account of the attention mechanism in which information across multiple levels of representation interacts to form an attentional gradient which reflects the overall representation of the attentional locus.
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