The remaining search space was divided into four regions, to allow control of object location effects. In half of the cases, all objects were clustered into one such region, in the remaining cases, objects were spread randomly and evenly across as many regions as possible. The unique object appeared an equal number of times in each region. Other controlled variables included frame rate, order of display usage, and button usage. Unique object is center of lower 3.
Unique object is second from left.
As dependent measures, we used accuracy of identification of the unique object, and search time in trials with correct identifications. Accuracy results for the coarse resolution, evenly degraded display indicated subjects were performing at chance levels. Search time results for these remaining displays are graphed in figures 3 and 4. With an evenly degraded coarse display, subject simply could not perform the task, while they could with all other displays. Two medium resolution, peripherally degraded displays did not significantly differ from the undegraded, fine resolution display.