title: Visual search and spatial attention: ERPs in focussed and divided attention conditions.
abstract: ERPs and performance were measured in divided and focussed attention visual search tasks. In focussed attention tasks, to-be-attended and to-be-ignored letters were presented simultaneously. We varied display load, mapping conditions and display size. RT, P3b-latency and negativity in the ERP associated with controlled search all increased with display load. Each of these measures showed selectivity of controlled search, in that they decreased with focussing of attention. An occipital N230, on the other hand, was not sensitive to focussing of attention, but was primarily affected by display load. ERPs to both attended and unattended targets in focussed attention conditions showed and N2 compared to nontargets, suggesting that both automatic and controlled letter classifications are possible. These effects were not affected by display size. Consistent mapping resulted in shorter RT and P3b-latency in divided attention conditions, compared to varied mapping conditions, but had no effect in focussed attention conditions.
authors.affiliation: Institute for Experimental Psychology, University of Groningen, The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: Wijers
authors.forename: T
authors.initials: T
authors.lastname: Okita
authors.forename: G
authors.initials: G
authors.lastname: Mulder
authors.forename: L J
authors.initials: LJ
authors.lastname: Mulder
authors.forename: M M
authors.initials: MM
authors.lastname: Lorist
authors.forename: R
authors.initials: R
authors.lastname: Poiesz
authors.forename: M K
authors.initials: MK
authors.lastname: Scheffers
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D009949:Orientation / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013028:Space Perception / Q000502:physiology*