Role of incentives in the training of the frontal EMG relaxation response

Male college students were assigned to a feedback condition in which an auditory signal was correlated with forehead electromyographic (EMG) responses or to a control condition in which a constant low tone was provided. Within each condition, half of the subjects were provided with an incentive for successful reductions of EMG levels from session to session. In the control condition incentives were actually given on the basis of performance of yoked feedback partners. The remaining subjects in each condition (no incentive) were instructed that the incentive was available for reliable participation in the experiment. Feedback subjects acquired lower EMG levels than control subjects, and the yoked-incentive subjects acquired lower levels than no-incentive subjects in the control condition. There were no major differences in EMG levels attributable to locus of control orientation. The results are discussed mainly in terms of implications of incentive variables for reinforcement analyses of biofeedback effects and the validity of the locus of control construct in this application.