GOAL-DIRECTED GUIDANCE OF ATTENTION - EVIDENCE FROM CONJUNCTIVE VISUAL-SEARCH

Conjunctive visual search is most difficult when distracter types ate in equal proportions and gets easier as the proportions diverge (e.g., E. Zohary & S. Hochstein, 1989). This may reflect restriction of sear ch to the feature shared by the target and the less-frequent distracte r. Alternatively, such effects could reflect target salience, which va ries with distracter ratio. In 2 experiments, 60 participants searched 64-element displays for a conjunctive target among distracters of 2 t ypes in various proportions. Participants were correctly informed (Exp eriment 1) or misinformed (Experiment 2) about which distracter type w ould be less frequent on most trials. In both experiments, the distrac tor-ratio effect was significantly influenced by the information provi ded to participants. These findings demonstrate the efficacy of top-do wn information in guiding attention and show that it can be applied fl exibly, weighted toward particular target features.