Abstract
Observers susceptibility to attentional capture during multiple object tracking was examined. Observers tracked 3–6 target objects as they moved within an array of identical, moving distractor objects for a period of 6 seconds. At the end of the tracking period, observers selected the objects believed to be the targets. On half of the trials, a new item (an abrupt onset) appeared suddenly within the display during the tracking period. These abrupt onsets disrupted tracking performance, as target identification accuracy was lower for onset trials compared to no onset (control) trials. Further analysis revealed that the abrupt onsets mainly disrupted tracking performance when they appeared near one of the targets (i.e., within 2 degrees). This disruption in tracking performance was confined to the target(s) near the abrupt onset; performance was equivalent to that in control trials for targets that were distant from the abrupt onset. Results are discussed in terms of the distribution of attention during multiple object tracking and the spatial resolution of attention.