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Nicole L. Jardine, Adriane E. Seiffert; Investigating virtual object structure in multiple object tracking. Journal of Vision 2010;10(7):314. doi: 10.1167/10.7.314.
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© ARVO (1962-2015); The Authors (2016-present)
Researchers use multiple object tracking to study how people attend to a set of identical, moving targets. Yantis (1992) showed that people conceive of multiple targets as parts of a virtual object (e.g. three vertices of a triangle), even when targets move independently. We investigated whether strengthening object structure by increasing the similarity of target motion would improve tracking performance. Observers tracked 4 of 12 identical dots moving in a box for 5.6 seconds in order to select targets from distractors at the end of the trial. To increase virtual object structure, we made targets maintain the form a rigid polygon that rotated, translated, expanded and contracted during the trial. Distractors formed two other polygons that behaved similarly in the same space. We also tested the effect of object symmetry: the polygons were either symmetric shapes, such as diamonds, or specific asymmetric shapes, such as skewed trapezoids. These conditions were compared to tracking randomly moving objects. Motion condition significantly affected proportion correct, F(3,30) = 31.50, p <.001. Tracking accuracy was significantly lower for random motion (53% correct) than for polygons (75%; t(10) = 6.51, p <.001) and there was no difference between asymmetrical and symmetrical polygons (t(10) > 1, p = .27, n.s.). Stronger object structure, but not object symmetry, may facilitate tracking. However, the results are also consistent with the interpretation that motion redundancy between tracked objects improves tracking performance. These observations are the first investigations of inter-target relationships on how people attend to multiple, moving targets.
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