title: The attentional effects of peripheral cueing as revealed by two event-related potential studies.
abstract: OBJECTIVE
  The mechanism of visual spatial attention elicited by peripheral cueing was investigated in two studies.
  
  
  METHODS
  Event-related potentials (ERPs) were recorded when the subjects were performing a spatial frequency discrimination task and a location discrimination task. Stimuli were randomly flashed in the left or right visual field. Prior to each stimulus a peripheral cue was presented with a validity of 75%.
  
  
  RESULTS
  The subjects responded faster to valid trials than to invalid trials. The earliest visual ERP component, C1, was not modulated by the cue validity, suggesting that visual spatial attention elicited by peripheral cueing does not involve striate cortex. Valid trials elicited larger contralateral P1 but a smaller contralateral N1 than invalid trials. The early onsets of these attentional effects show that spatial attention affects stimulus processing at early sensory/perceptual stages. The latencies of contralateral P1 and contralateral N1 were shorter for invalid trials, however. The ipsilateral N1 was enhanced by valid trials in the spatial frequency discrimination task but was not in the location discrimination task, whereas the contralateral N1 was larger for invalid trials than for valid trials in both tasks.
  
  
  CONCLUSIONS
  The results indicate that involuntary allocation of attention involves different mechanisms from voluntary allocation of attention.
authors.affiliation: Beijing Laboratory of Cognitive Science, University of Science and Technology of China, 100039, Beijing, China. shimin.fu@psy.ox.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Fu
authors.forename: S
authors.initials: S
authors.lastname: Fan
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Zhuo
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D003463:Cues; D004192:Discrimination, Psychological / Q000502:physiology; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D008297:Male; D011930:Reaction Time; D015203:Reproducibility of Results; D013028:Space Perception / Q000502:physiology