Abstract or Table of Contents
We reduced time to detect target symbols in mock radar screens by partitioning displays in accordance with task instructions. Targets appeared among distractor symbols either close to or far from the display center, and participants were instructed to find the target closest to the center. Search time increased with both number of distractors and distance of target from center, and the effect of distractors was considerably greater for far than close targets. However, when close and far regions were delineated by a centrally-presented "range ring", the distractor effect was substantially reduced, especially for far targets. We suggest that range rings focus attention on specific regions of the screen and aid in the determining of which regions have already been searched.