Parallel search for a conjunction of color and orientation" The effect of spatial proximity

The present study shows that search for a conjunction of color and orientation can be performed in parallel when the target is embedded in a spatially contiguous subset of nontarget elements. When the colored subset is spatially scattered among other items in the display, serial search through the colored subset is necessary. The results provide evidence for the notion of sequential parallel processing in which the first global stage allows the detection of a subset of elements defining a candidate object, followed by a second local parallel stage which allows a pop-out of the conjunction target among the remaining elements. Experiment 1 shows parallel search among the subset when the elements are spatially grouped and serial search among the subset when the elements are spatially scattered within the display. Experiment 2 shows that parallel processing of a conjunction target is not limited to small display sizes but occurs in displays consisting of up to 49 elements. Implications of the present findings for current theories of visual search are discussed. PsyclNFO classification: 2323