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Aysu Suben, Brian Scholl; Recently disoccluded objects are preferentially attended during multiple-object tracking. Journal of Vision 2012;12(9):542. doi: 10.1167/12.9.542.
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© ARVO (1962-2015); The Authors (2016-present)
The human visual system allows multiple featurally-identical objects to be simultaneously tracked, and the presence of periodic occlusion does little or nothing to impair this ability. However, studies of the resources that underlie this ability demonstrate the periods of momentary occlusion nevertheless demand the allocation of extra bursts of attention - the so-called "attentional high-beams effect". Here we explored how and when these resources are allocated. Across several experiments, observers tracked multiple featurally-identical objects as they moved about displays containing static occluders. At the same time, observers also had to detect small probes that appeared sporadically on the occluders, or on targets while they were in one of six states: unoccluded, about to be occluded, partially occluded, fully occluded, partially unoccluded, or just recently unoccluded. Probe detection rates for these categories were taken as indexes of the distribution of attention. (Distractors were probed just as often, so that probes did not predict target identity.) We replicated the high-beams effect: probe detection rates were higher for occluded targets than visible targets. For partially occluded targets, however, we observed an asymmetry: objects in the process of becoming disoccluded were still attentionally prioritized, but objects in the process of becoming occluded were not. This same qualitative pattern occurred for fully visible targets that were very close to occluders, with a benefit for targets that had been recently occluded, but no benefit for targets that were about to become occluded. Thus, the highbeams effect occurs not only for occluded (and thus invisible) targets but also for fully visible (but just-recently occluded) targets. This surprising result also emphasizes that the highbeams effect truly reflects a functional difference, rather than a visual difference. This effect of dynamic attention also appears to be subject to a form of inertia, but is not driven predictively.
Meeting abstract presented at VSS 2012
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