title: Attentional selection and identification of visual objects are reflected by distinct electrophysiological responses.
abstract: Lateralised ERP responses were measured over posterior visual brain regions in response to visual search arrays that contained one colour singleton. In the localisation task, responses were determined by the visual hemifield where this singleton was presented. In the discrimination task, they were determined by the singletons' shape. While an N2pc component was elicited in an identical fashion in both tasks, a subsequent sustained contralateral negativity was consistently present at posterior sites in the discrimination task only. This dissociation demonstrates that these two activations reflect distinct visual processing stages. We suggest that while the N2pc reflects the ability of the visual system both to identify and localise a relevant stimulus in the scene, the late sustained activity reflects the subsequent in-depth analysis and identification of these stimuli.
authors.affiliation: Department of Cognitive Sciences and Education, University of Trento, Trento, Italy. veronica.mazza@unitn.it
authors.forename: Veronica
authors.initials: V
authors.lastname: Mazza
authors.forename: Massimo
authors.initials: M
authors.lastname: Turatto
authors.forename: Carlo
authors.initials: C
authors.lastname: Umiltà
authors.forename: Martin
authors.initials: M
authors.lastname: Eimer
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology