Selective processing of superimposed objects: an electrophysiological analysis of object-based attentional selection

• Published in: Biological psychology 1997-03, Vol.45 (1-3), p.159-182
• Main Authors: Weber, Timothy A., Kramer, Arthur F., Miller, Gregory A.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Attention - physiology; Color Perception; ERPs; Evoked Potentials; Female; Form Perception; Humans; Male; Object representation; Object-based attention; Reaction Time; Space Perception; Spatial attention
• ISSN: 0301-0511; 1873-6246
• DOI: 10.1016/S0301-0511(96)05227-1

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.