title: Objective assessment of the human visual attentional state.
abstract: OBJECTIVE
  The purpose of this study was to develop an objective way to assess human visual attention using the alpha-band component of the visual-evoked potential (VEP).
  
  
  METHODS
  Six different attentional conditions were tested: eyes-open, eyes-closed, eyes-closed with backwards number counting, and three rapid-serial visual presentation (RSVP) tasks. Eighteen visually normal, young-adult subjects (ages 21-28 years) were tested binocularly at 1 m for each condition on two separate days. The Diopsys™ NOVA-TR system was used to obtain the visual-evoked potential (VEP) and extracted alpha wave and its related power spectrum. Additionally, the Visual Search and Attention Test (VSAT) was administered as a subjective measure of visual attention.
  
  
  RESULTS
  Subjects exhibited significant decreases in power in the alpha band when comparing the eyes-closed with the eyes-open conditions, with power in the eyes-closed condition being, on average, twice as large. The response from the other four conditions did not reflect the differential attentional demands. The ratio of the power in the eyes-closed condition to the eyes-open condition in the lower-alpha frequencies (8-10 Hz) was found to be significantly correlated with the group's performance on the VSAT, especially the 10-Hz component.
  
  
  CONCLUSIONS
  An individual's ability to attenuate their alpha component during visual processing may be a predictor of their visual attentional state. These findings solidify the role of the VEP alpha subcomponent as an objective electrophysiological correlate of visual attention, which may be useful in the diagnosis and treatment of human visual attention disorders in the future.
authors.affiliation: Department of Biological and Vision Sciences, SUNY State College of Optometry, 33 West 42nd Street, New York, NY 10036, USA. kwilleford@sunyopt.edu
authors.forename: Kevin T
authors.initials: KT
authors.lastname: Willeford
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ciuffreda
authors.forename: Naveen K
authors.initials: NK
authors.lastname: Yadav
authors.forename: Diana P
authors.initials: DP
authors.lastname: Ludlam
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D012016:Reference Values; D014786:Vision Disorders / Q000175:diagnosis* / Q000503:physiopathology; D014792:Visual Acuity; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult