Selective processing of superimposed objects: an electrophysiological analysis of object-based attentional selection.
We investigated whether object-based attentional selection occurs from grouped-array or spatially-invariant representations. Subjects were presented with colored objects and asked to judge whether a particular color/shape conjunction was present, regardless of whether the color and shape were part of a single object (same-object condition) or occurred on two different objects (different-object condition). RTs and accuracies were recorded for subjects judgments. ERP components, in particular the P1 and N1, were elicited both from the presentation of the target objects and from a post-display probe that was employed as an index of spatial attention. Consistent with predictions of object-based selection models, RTs and accuracies were faster on same than on different object trials. N1s elicited by the target objects and P1s elicited by the post-display probes discriminated between same and different object trials when the two target objects were superimposed. These data are consistent with the proposal that object-based selection is spatially mediated, even in the case of partially overlapping objects. The data are discussed in terms of space- and object-based models of visual selective attention.
Weber
T A
TA
Department of Psychology, University of Illinois at Urbana-Champaign, Beckman Institute, Urbana 61801, USA.
Kramer
A F
AF
Miller
G A
GA
D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D003118:Color Perception; D005071:Evoked Potentials; D005260:Female; D005556:Form Perception; D006801:Humans; D008297:Male; D011930:Reaction Time; D013028:Space Perception