Electrodermal activity (EDA) is a common term for all electrical phenomena in the skin. The term comprises galvanic skin response (GSR), skin potential, peripheral autonomic surface potentials, etc. It can be measured with or without the application of an external voltage to the skin, although the use of a 0.5-V constant external voltage is most common. Electrodermal recording dates back to the late 19th century and has been widely used as a psychophysiological method (Boucsein, 1992). It is easy to measure and interpret.