title: Test-retest reliability of cognitive EEG.
abstract: OBJECTIVE
  Task-related EEG is sensitive to changes in cognitive state produced by increased task difficulty and by transient impairment. If task-related EEG has high test-retest reliability, it could be used as part of a clinical test to assess changes in cognitive function. The aim of this study was to determine the reliability of the EEG recorded during the performance of a working memory (WM) task and a psychomotor vigilance task (PVT).
  
  
  METHODS
  EEG was recorded while subjects rested quietly and while they performed the tasks. Within session (test-retest interval of approximately 1 h) and between session (test-retest interval of approximately 7 days) reliability was calculated for four EEG components: frontal midline theta at Fz, posterior theta at Pz, and slow and fast alpha at Pz.
  
  
  RESULTS
  Task-related EEG was highly reliable within and between sessions (r0.9 for all components in WM task, and r0.8 for all components in the PVT). Resting EEG also showed high reliability, although the magnitude of the correlation was somewhat smaller than that of the task-related EEG (r0.7 for all 4 components).
  
  
  CONCLUSIONS
  These results suggest that under appropriate conditions, task-related EEG has sufficient retest reliability for use in assessing clinical changes in cognitive status.
authors.affiliation: EEG Systems Laboratory & SAM Technology, 425 Bush Street, San Francisco, CA 94108-3708, USA. linda@eeg.com
authors.forename: L K
authors.initials: LK
authors.lastname: McEvoy
authors.forename: M E
authors.initials: ME
authors.lastname: Smith
authors.forename: A
authors.initials: A
authors.lastname: Gevins
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D013647:Task Performance and Analysis