Figure 1.

Multiple object tracking plus missing item localization. At the beginning of each trial 4 items blinked off and on to identify them as targets. Then all items moved about the display and participants counted the total number of times a target circle touched a red line. At an unpredictable time between 6 and 10s from the onset of motion, there was a brief 200ms blank interval, followed by a final test display consisting of stationary items. Either 1 item was missing (a random target or distractor) or 4 items were missing (all of the targets or all of the distractors). A single digit at the center of the display informed participants of how many items were missing. The task was to indicate where the missing items were located, clicking directly on the location of a single missing item, or on the “centroid” of 4 missing items.