Galvanic skin response is an older term for what is usually called skin conductance. It refers to a measurement of the skin's ability to conduct electricity, which increases briefly in the presence of sweat produced by physiological stimulation or arousal.
Galvanic skin response is typically measured on the hands and feet. When emotional arousal is prompted by stimuli such as fear, anger, sexual arousal or pinpricks, the sweat glands produce a small sympathetic response that increases the skin's electrical conductivity. Two other behaviors associated with increased galvanic skin response include blushing and sweating due to embarrassment. Galvanic skin response is one of the physiological responses measured in lie detector tests using polygraph machines.