A Beginner’s Behavioral Test Guide to Biofeedback Instrumentation

Abstract

This chapter focuses on a few techniques that a practitioner should know when he uses biofeedback equipment. Since biofeedback is a psychophysiological mirror, it is useful only if the equipment records and amplifies the biological signal accurately. The techniques discussed will apply to electromyographic (EMG), thermal, electrodermal (EDR or GSR), or skin potential response (SPR), and electroencephalic (EEG) biofeedback equipment. Obviously these concepts can be extended to other feedback devices not discussed here. The recorded measures must be accurate so that the practitioner can interpret changes in the feedback signal as indications of changes in the psychophysiology or autonomic self-regulation of the trainee (Peper, 1974). (The term trainee is used instead of patient or client as I perceive biofeedback training as a learning tool.) For example, the EMG of the forearm extensor could be as high as 18 $μ$V even though there is no voluntary muscle tension. The reading may imply that the person had tensed his forearm extensors through lifting the fingers or bending the hand back at the wrist, and that the reading is not due to artifacts such as 60-Hz or sensor (electrode) lead movements. To avoid misinterpretation of the recorded physiological data, the practitioner should be familiar with the human interface of the equipment: (1) knowledge of the equipment, i.e.. the flow diagram, which is a schematic representation of how the signal is processed; (2) external, internal, and physiological factors affecting the biological functions recorded; and (3) suggested behavioral testing procedures to assess whether the biofeedback equipment is working.