To many, biofeedback is synonymous with the "alpha wave" craze of the 1960s and 1970s. Alpha brain waves—those with a frequency of 8 to 15 cps—usually are generated during periods of relaxation or light sleep. Since they often predominate in Indian yogis and others who meditate frequently, alpha wave production has been associated by some with the serene emotional state of such persons.
Indeed, learning to "go into alpha" became the rage, and in 1971, ninety-nine different companies were producing EEG biofeedback machines for self-instruction. By using such equipment, a subject trained himself to consciously manipulate his own brain waves.
Biofeedback, however, is not a magical method of mind or mental state control, but simply a technique that uses instruments to reveal to a person the covert activities of his or her body. Available biofeedback instruments measure a variety of physiological parameters, including heart rate, blood pressure, skin temperature, and