Biofeedback

Biofeedback is a means by which a person can mentally influence a natural physiologic process that may or may not be consciously regulated under normal conditions. This could include lowering blood pressure, regulating the heart rate, or influencing the skin temperature.

Deliberate control of bodily functions is not a new accomplishment. Many historical accounts exist of Indian yogis who controlled their body temperature with such precision that they could make the palm of one hand warmer or cooler on one side than the other. Biofeedback also played a role in the performances of the famous escape artist Harry Houdini who consciously suppressed his gag reflex to suspend a key in his throat so as to regurgitate it later to unlock his elaborate bindings.