Biofeedback is a way to gain control of physical processes that are not normally under conscious control. For example, people can learn to warm their hands by watching a thermometer while focusing mental activity on trying to get the temperature to increase by consciously relaxing to increase blood flow to the hands. In general, instruments are used to give “biofeedback”, on temperature, pulse rate, electrical signals from muscle activation (EMG), electrical signals from the heart (EKG), electrical signals from the brain (EEG) etc. Usually biofeedback is done in the office of a professional who has professional equipment.