Assessed the differential effects (on experiential reports of anxiety) of actual performance and perceived success at an EEG biofeedback task. 10 college students who were high in trait anxiety (MMPI, State-Trait Anxiety Inventory) underwent training in either the suppression of enhancement of EEG alpha activity with the expectation that success at their biofeedback task would result in reductions of chronic anxiety levels. Both groups experienced significant reductions in both trait and state anxiety. Anxiety reductions were highly correlated with the trainees’ ratings of perceived success at the feedback task but were unrelated to either the direction or magnitude of the changes in their alpha activity. (27 ref)
Plotkin, W & Rice, Kathleen. (1981). Biofeedback as a placebo: Anxiety reduction facilitated by training in either suppression or enhancement of alpha brainwaves. Journal of consulting and clinical psychology. 49. 590-6. 10.1037/0022-006X.49.4.590.