Abstract

The visual search paradigm has been widely used as a tool to uncover visual mechanisms underlying selective attention (Treisman & Gelade, 1980; Wolfe, 1998). In a standard visual search task, participants are required to look for a predefined target among a set of distractors in a display. Search effi-ciency can be estimated as the slope of response times as a function of the number of items in the display. In some cases, search seems to be effortless (resulting in a very shallow slope), but in other cases, searching for a target among dis-tractors can be very inefficient (resulting in a very steep slope). A robust phenomenon related to search efficiency is search asymmetry. Search asymmetry is defined as a change in search efficiency that occurs when target-distractor map-ping is reversed (Treisman & Gormican, 1988; Treisman & Souther, 1985; Wolfe, 2001). That is, search for A among B is