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Elias H. Cohen, Zenon W. Pylyshyn; Searching through subsets of moving items. Journal of Vision 2002;2(7):541. doi: 10.1167/2.7.541.
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© ARVO (1962-2015); The Authors (2016-present)
We have been exploring the visual search paradigm under conditions where items to be searched move in an unpredictable manner in order to determine if the visual system can reference objects that occupy changing locations. In the present study, the moving search task was combined with a multiple-object-tracking task in which 3 to 5 items were tracked among an equal number of distractors and in which the critical item, when present, occurred in the tracked subset. Subjects tracked a number of placeholders, which, after a few seconds, changed into search items. We showed that under these conditions observers are able to confine their search to the tracked items. For example, when the search subset was a feature set, then even when the nontracked distractor set contained elements with each of the features that defined the critical item (i.e., that made the entire superset of items a conjunction search set), observers were faster at finding a present target. Additionally, subjects were faster for smaller conjunction subsets. This result shows that in the multiple-object tracking paradigm, observers do select the target set as a whole, confirming a finding of Burkell & Pylyshyn (Spatial Vision, 11, 225–258, 1997) that items selected by visual indexes can be accessed directly.
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