Search for Conjunctively Defined Target can be Selectively Limited to a Color-Defined Subset of Elements
INSTITUTE FOR PERCEPTION RVO-TNO SOESTERBERG (NETHERLANDS)
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When searching for a conjunctively defined target, response latencies usually increase with the number of distractor elements, suggesting serial, self-terminating search through all display elements. However, Egeth, Virzi and Garbart 1984 showed that subjects do not necessarily search all display elements, but can limit their search to a color-defined subset of the elements. The present experiments tested Egeth et al.s conclusions using an improved paradigm. Subjects searched for a target defined as a conjunction of a color and an orientation. RTs for target present trials increased with the number of elements in that color and were independent of the number of elements in the other color, a finding which replicates Egeth et al.s results. Experiment 1 showed also that selective search of a color-defined subset did not depend on the saliency of the subset. Experiment 2 showed that selective search can be purely color-based and does not depend on luminance or brightness of the subset. Experiment 3 showed that subjects can flexibly change the subset they are searching for trial by trial. Implications of the present findings for current theories of visual search are discussed.
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