The quest for the EEG reference revisited: A glance from brain asymmetry research

  1. Dirk Hagemann1,2,
  2. Ewald Naumann3,*,
  3. Julian F. Thayer1

Article first published online: 14 MAR 2003

DOI: 10.1111/1469-8986.3850847

Issue

Psychophysiology

Psychophysiology

Volume 38, Issue 5, pages 847–857, September 2001

Additional Information

How to Cite

Hagemann, D., Naumann, E. and Thayer, J. F. (2001), The quest for the EEG reference revisited: A glance from brain asymmetry research. Psychophysiology, 38: 847–857. doi: 10.1111/1469-8986.3850847

Author Information

  1. 1

    Laboratory of Personality and Cognition, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA

  2. 2

    Department of Psychology, University of Maryland, Baltimore Country, USA

  3. 3

    Fachbereich I—Psychologie, Universität Trier, Germany

* Address requests for reprints to: Ewald Naumann, FB I—Psychologie, Universität Trier, Universitätsring 15, 54286 Trier, Germany. E-mail: naumann@uni-trier.de.

Publication History

  1. Issue published online: 14 MAR 2003
  2. Article first published online: 14 MAR 2003

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Keywords:

  • Electroencephalography;
  • Reference problem;
  • Topographical analysis;
  • Hemispheric lateralization

Recent findings suggested that the choice of the EEG reference might be a critical issue for the study of anterior asymmetry in the alpha band. The present paper investigates the validity of different reference schemes for the measurement of alpha asymmetry. A 32-channel resting EEG was recorded with a common vertex reference (Cz), and transformed into computer-averaged ears (A1 + A2), average reference (AR), and current source density derivations. A correlation analysis of an alpha asymmetry measure between all derivation schemes indicated a poor convergent validity for anterior sites but an excellent convergent validity for posterior sites. Further analyses suggested the presence of substantial alpha activity at the various reference sites (Cz, A1 + A2, AR), which might be similar in magnitude to anterior but smaller than posterior alpha. These findings suggest that the validity of a reference scheme is a function of the signal-to-noise ratio of the electrical activities at target and reference sites. The limitations of each reference scheme for the measurement of anterior alpha asymmetry are discussed.

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