Abstract

Visual marking refers to indicating the items that have already been processed in a display. So far, most researchers have assumed that marking is performed accurately in both enumeration and search tasks. On the basis of this assumption, it has been claimed that linearity and a 2:1 target-absent/target-present ratio exist for a conjunction search. In Experiments la and 1b, subjects were asked to judge whether the number of items in a display is odd or even. Positively accelerating RT functions were found as the number of items increased, which suggested that marking is not accurate. In Experiments 2 & 3, marking accuracy far the distractors were examined. Contrary to Experiment 1, marking for the distractors seemed to be accurate. The implications of these results were considered.