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Alex Kushnier, Zenon W Pylyshyn; Can flashing objects grab visual indexes in multiple object tracking?. Journal of Vision 2003;3(9):581. doi: 10.1167/3.9.581.
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© ARVO (1962-2015); The Authors (2016-present)
Visual Indexing Theory (Pylyshyn, 1989, 2001) assumes that events such as flashes cause indexes to be automatically assigned, or “grabbed,” by the flashed objects. It also assumes that once assigned, indexes stay assigned to the same individual objects as these objects move around in the visual field, and even when they briefly disappear, thus accounting for the high performance observed in multiple object tracking (MOT) studies. In the present study we ask whether already assigned indexes can be draw away by flashing nontargets during tracking. Method: Observers tracked 4 targets among a total of 8 identical randomly-moving objects. Approximately midway through the 6 s tracking trial, 4 objects flashed on and off for 300 ms: two of these were targets being tracked and the other two were nontargets. We examined only those trials (37% of the total trials in our case) in which exactly one target was lost and replaced by one nontarget, since in those cases it was unambiguous which target had been lost and which nontarget erroneously selected as its replacement. For these trials we asked: (1) was the dropped target more often one that had flashed than one that had not? and (2) was the erroneously substituted nontarget more often one of the distractor objects that had flashed than one that had not. Results: The results showed that (1) the target object that was lost was no more likely to be one that had flashed than one that had not flashed, and (2) the nontarget that was erroneously selected was significantly more often one that had flashed. We interpreted these results to suggest that once objects were indexed for tracking, flashing them did not tend to cause the index to be dropped, but flashing nontargets tended to draw indexes away from tracked targets.
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