Feelings and emotions: roles for electrophysiological markers.

Asymmetrical electroencephalogram (EEG) alpha activity over anterior regions of the scalp predicts a variety of outcome measures of interest to emotion researchers. This vast and diverse literature is examined from three different viewpoints. First, the organization of this vast literature is contrasted from theoretical and statistical perspectives, and the advantages and disadvantages of each perspective are considered. Second, the correlates of EEG asymmetry are sometimes treated as criterion (dependent) measures and at other times treated as predictor (independent) measures. Differences in the interpretation of each are surveyed, and the need for attention to whether EEG asymmetry is a simple correlate, mediator, or moderator of the associated affective measures is noted. Finally, the studies of EEG asymmetry and emotion that adopt a psychological perspective are contrasted with those that adopt a neurophysiological perspective, and the import of each for theory, experimental design, and analytic strategy is discussed.