Biofeedback regulation of temporal EEG alpha asymmetries.

Integrated EEG alpha was recorded from T3 and T4. Larger R alpha/L alpha ratios were defined as right asymmetry, relatively smaller ratios as left asymmetry. In different phases of the study, participants attempted to identify the presence of the EEG asymmetries and to produce the EEG asymmetries during auditory biofeedback, and were tested on hemisphere-specialized cognitive tasks while attempting to produce the EEG asymmetries. Experiential descriptions of the EEG asymmetries were obtained throughout using a set of bipolar scales. Some participants were able to identify the presence of the EEG asymmetries (p less than .05). As a group there was numerically small but significant (p less than .05) biofeedback control of the EEG asymmetries, but no improvement across sessions of training. There were marked individual differences in the ability to control the EEG asymmetries and in L alpha and R alpha during control. During baselines L alpha and R alpha were strongly positively correlated across time. Experiential descriptions were not consistent across participants. Effects of EEG asymmetries on performance of hemisphere-specialized tasks were demonstrated for one participant.