title: A search order lost effect: ignoring a singleton distractor affects visual search efficiency.
abstract: Four experiments investigated after-effects of attentional capture by a target-feature singleton distractor. In Experiments 1 and 3, participants searched for an orientation singleton target in a visual display and responded to a reported-attribute in the target (a compound search task). On some trials, a singleton distractor with the same orientation as, but a different color from, the target occurred. In the singleton distractor-absent trials reaction times for targets were unchanged irrespective of the number of nontargets. However, on singleton distractor-present trials, target reaction times increased with number of displayed nontargets. Ignoring target-feature singleton distractors induced inefficient visual searches slowed target search, suggesting that targets were searched serially in the presence of a singleton distractor induces inefficient serial search. This result implies that the search order, corresponding to relative item salience, is lost following attentional capture by a singleton distractor. Subsequent experiments explored conditions that might elicit the search order lost effect. It did not occur when task-irrelevant singleton distractors occurred in a compound search task (Experiment 2) or when target-feature (Experiment 4) singleton distractors occurred in a simple target detection task. Together, results suggest that the search order lost effect is mediated by dynamic computations involving saliency and feature maps. An explanation of this effect is proposed.
authors.affiliation: Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan. t.kumada@aist.go.jp
authors.forename: Takatsune
authors.initials: T
authors.lastname: Kumada
mesh_terms: D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D011930:Reaction Time; D014796:Visual Perception / Q000502:physiology*