biofeedback, method for learning to increase one's ability to control biological responses, such as blood pressure, muscle tension, and heart rate. Sophisticated instruments are often used to measure physiological responses and make them apparent to the patient, who then tries to alter and ultimately control them without the aid of monitoring devices. Biofeedback programs have been used to teach patients to relax muscles or adjust blood flow in the case of headache, to help partially paralyzed stroke victims activate muscles, and to alleviate anxiety in dental patients.