A salient distractor does not disrupt conjunction search.
Leading theories of attention posit that bottom-up and top-down factors simultaneously affect attentional priority in visual search. Recent evidence, however, suggests that subjects may rely exclusively on top-down guidance when searching for a target defined by a specific known feature (Bacon & Egeth, 1994). In the present experiment, we addressed this issue in a conjunction search task. We investigated how searching for a green O among green Ts and red Os is affected by the presence of a distractor with a unique shape (green X), color (blue O), or both (blue X). We showed that the salient distractor does not disrupt performance on target-present trials, but produces a large interference on target-absent trials. We conclude that salience-based and top-down processes are alternative modes of guidance, rather than joint contributors in the allocation of attentional priority.
Department of Psychology, Tel Aviv University, Israel. domi@freud.tau.ac.il
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D001288:Attention; D005403:Fixation, Ocular; D006801:Humans; D011897:Random Allocation; D011930:Reaction Time; D014796:Visual Perception