A Primer of Biofeedback
A major application for biofeedback is to provide tools for detecting and managing psychophysiological arousal. As health care fields matured, it became clear by the early 1970s that frequent, excessive, and sustained psychophysiological tension and overarousal cause or exacerbate many health problems. Interest in detecting and managing these states intensified. By the same time, improved biomedical electronics had made it practical to monitor previously invisible physiological processes associated with overarousal.
The natural combination of these developments in health and technology found expression in the new field of biofeedback, in which the languages and concepts of psychology, physiology, and electronics freely intermingle. The terms "stress," "anticipation," "autonomic arousal," and "muscle fibers" are found in the same sentences as "electromyography" (EMG), "microvolts," "bandwidths," and "filters." Such hybrid sentences usually contain at least some mystery to those (i.e., most of us) who are not fluent in all these languages. Probably the greatest mystery among biofeedback devotees and beginners is in the language of electronics. Of the three languages spoken in biofeedback, this is the least similar to ordinary language.
This chapter aims to put into ordinary language basic technical matters of practical importance in biofeedback. Technical concepts are introduced through analogy or heuristic description, such that they can become a usable part of the reader's biofeedback language. This chapter contains many judgments on the practical importance of things encountered in biofeedback, and to that extent represents my own views on the subject, especially in matters where no definitive conceptual, empirical, or practical view holds sway in the field.
This chapter is focused on basic electronic and measurement concepts for EMG, temperature, and electrodermal biofeedback. (Electroencephalographic biofeedback is covered by Neumann, Strehl, & Birbaumer in Chapter 5 of this volume.) It is focused on the "front end," where electrodes, basic electronics, and feedback modes interact with clinicians and clients. Other chapters address the "back end," where computers and myriad forms of feedback and data recording are devised for clinical biofeedback or research. Although comput