Galvanic Skin Response, also known as electrodermal response (EDR) or psychogalvanic reflex (PGR), is a method of measuring the electrical resistance of the skin and interpreting it as an image of activity in certain parts of the body. Changes in the electrical properties of the skin in response to stress or anxiety can be measured either by recording the electrical resistance of the skin or by recording weak currents generated by the body. Stress thermometers are a less sophisticated version to teach hand-warming techniques. All of these yield feedback or information and are used to teach individuals to better control stress. Basically, increased stress levels lessen the blood flow to the hands and feet. This causes a decrease in peripheral (hand/foot) temperatures. With the monitoring help of GSR, an individual can learn to control that temperature. What is happening is biofeedback or the ability to consciously control the dilation and constriction of blood vessels in the arms and legs.