IS THERE FEATURE-BASED ATTENTIONAL SELECTION IN VISUAL-SEARCH

A new paradigm combines attentional citing and rapid serial visual pre sentation to disentangle the effects of perceptual filtering and locat ion selection. Observers search successive, superimposed arrays, in wh ich feature values are alternated for a target numeral among letters. Two dimensions, size (small, large) and color (red, green) are tested. Selective attention to feature values is jointly manipulated by instr uctions. presentation probabilities, and payoffs. In Experiment I, the attended feature provides temporal, not spatial, information; observe rs show no attentional costs or benefits in response accuracy. In Expe riment 2, the attended feature indicates a unique location. observers show consistent attentional costs and benefits. Selective attention to a particular size or color does not cause perceptual exclusion or adm ission of items containing that feature; it acts by guiding search pro cesses to spatial locations that contain the to-be-attended feature.