Biofeedback and Self-Regulation, Vol. 13, No. 2, 1988 Feedback Delays and Relaxation Expectancies in EMG Biofeedback I Brian R. Monsma, 2 Alan G. Glaros, ~ and Mark A. Lumley 4 Wayne State University The use of noncontingent feedback controls in studies of the efficacy and process of electromyographic (EMG) biofeedback may yieM results confound- ed by differential expectancies for relaxation. Furthermore, the role of ex- pectancies in producing psychological and physical relaxation as well as reducing muscle activity is unclear. This study investigated the effects o f feed- back delays and induced relaxation expectancies on EMG activity and ex- perienced relaxation. One hundred four non-clinical subjects participated in one auditory frontal EMG biofeedback training session. Subjects were assigned to one o f four computerized feedback delay conditions (0.003 7, O.7493, 2.2481, 6. 7444 s) and to one of two relaxation expectancy conditions (positive or negative). During 20 minutes of biofeedback training, all groups decreased frontal activity. Feedback delays interacted with training epochs in affect- ing EMG; the longest delay group reduced frontal activity more slowly than the shortest delay group during training. Positive relaxation expectancies produced greater experienced relaxation than did negative relaxation expec- tancies. Instrumental and expectancy factors in EMG biofeedback appear ~This study was completed by the first author under the direction of the second author in par- tial fulfillment of the requirements for the Master of Arts degree. We gratefully acknowledge the computerization advice and assistance provided by Larry Wheeler, and the assistance in data collection provided by Dawn Dexter and Michael Winstanley. 2Brian Monsma is currently at the Pain Rehabilitation Clinic, Mary Free Bed Hospital, Grand Rapids, Michigan. 3Address all correspondence to Alan G. Glaros, Department of Behavioral Science, University of Missouri-Kansas City, 650 East 25th Street, Kansas City, Missouri 64108. 4Mark Lumley is currently at the University of Florida. 113 0363-3586/88/0600-0113506.00/0 © 1988 Plenum Publishing Corporation