Like hypnosis and acupuncture, biofeedback works, Lake them, it is also easier to demonstrate than explain, easier to sensationalize than analyze. Barbara Brown, a leading practitioner in the therapy and a faculty member of UCLA Medical School, surveys the state of the art in this book. In general, biofeedback is a technique by which some unconscious physiological activity is monitored and the information supplied to a person in the form of an auditory or visual signal. If the biofeedback is successful, the individual learns awareness and control of the activity, be it heart rate, skin temperature, or muscle tone. The biofeedback information is often supplied in concert with relaxation techniques, knowledge about the nervous system, or other cognitive inputs provided by a sympathetic therapist. These factors, plus great variety in the manner of monitoring or the design of treatment, make it as yet impossible to build up a firm body of knowledge of the operation of biofeedback. The lay reader, in fact, is likely to be bewildered by contradictory or inconclusive results, incommensurable experiments, and, usually, the small number of patients in any given study. All this detail is cloaked in the academic and excessive verbiage typical of review articles in scientific journals. On the other hand this information provides a very useful service for medical and behavioral science professionals, telling them about the use of biofeedback in a wide range of experimental and clinical settings as well as offering suggestions for future research. In summary, Brown says that biofeedback has been most successful in treating stress and stress-related illnesses, especially when accompanied by relaxation techniques. While appendices listing references, sources of equipment, and a number of relaxation exercises may guide the general reader, the primary audience for the book will be professional.