On the efficiency of visual selective attention: Efficient visual search leads to inefficient distractor rejection

The ability to ignore irrelevant peripheral distractors was assessed as a function of the efficiency in visual search for a target at the center of a display. Efficient target search, among dissimilar nontargets, led to greater distraction than inefficient search, among similar nontargets. This seemingly paradoxical result is predicted by the recent proposal (Lavie, 1995a) that irrelevant processing can be prevented only by increasing the load for relevant processing. Varying the set size of similar items in the central search task demonstrated that interference from irrelevant distractors was eliminated only with more than four relevant items. These results demonstrate how capacity limits determine the efficiency of selective attention, and raise questions about some standard assumptions of most visual search models.