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Meriam Naqvi, Deborah Aks, Navpreet Singh, Sanjana Mohan, Chisom Emeana, Hannah Canuto, Zenon W. Pylyshyn; Studying the effect of eye-movements and interruptions in Multiple Object Tracking. Journal of Vision 2014;14(10):355. doi: 10.1167/14.10.355.
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Studies of disrupted multiple object tracking (MOT) have shown tracking is better the closer disappearing items are to their reappearance sites: Items that halt while hidden are easier to track than those that move (Keane & Pylyshyn, 2006). These results suggest that past object-locations are remembered when items disappear briefly from view. Here we examine where we look at MOT to learn whether a bias from eye-movements may account for better tracking when items halt during their disappearance. If gaze plays a role, than fixating the center of the screen should reduce the halt-move difference in MOT. Method. Subjects tracked 4 of 8 identical circles in a MOT task. Subjects were either free to move their eyes during tracking, or they fixated on the center of the display. Midway through each 5s trial, subjects were cued with a sound to blink their eyes . Eye-blinks triggered: (1) Items to disappear for 150, 450, or 900ms, and (2) Items to halt or move during their disappearance. The eye-blink induced disruption was used to remove the (possible confound of) abrupt offset when items disappear. Results. MOT is better when subjects are free to move their eyes than when they fixate the center of the screen. More important, both fixation conditions produce better tracking when items halt, and when disappearing items are close to their reappearance sites. Conclusions. A variety of factors can account for the impaired MOT performance when subjects fixate the center of the screen : Cognitive effort needed to sustain fixation, blurring of items in the periphery, or limitation in covert attention. More noteworthy is the robustness of the halt-move effect even when fixating the center of the display. This suggests that position-coding is not just due to eye-movements.
Meeting abstract presented at VSS 2014
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