The Effects of Reward on Occipital Alpha Facilitation by Biofeedback

Abstract
Eighty male undergraduates were randomly assigned to one of four treatment conditions: an auditory stimulus denoted the presence of alpha in a feedback condition: a backup reinforcement condition received feedback plus a choice of money or extra experimental credit contingent upon increasing alpha 1.5 times baseline levels; a yoked control group received bogus feedback; another control group received no feedback. All groups received 6 4‐min trials of training. Backup reinforcement was clearly more effective in enhancing; alpha than any other treatment condition. In fact, the conventional feedback condition performed no better than a control condition which received no feedback, although both significantly increased alpha over trials. The only group which did not significantly increase alpha was the yoked control condition, whose performance, differed significantly over trials from the other controls. These findings demonstrate the hazard of inferring alpha control from increases above initial baselines, as many studies have done. Moreover, they seem to demonstrate the efficacy of augmenting feedback with additional reinforcement.