Electrodermal screening has its earliest roots in what was called galvanic skin testing. The galvanic skin response, a method of measuring the electrical resistance of the skin, was discovered in the early 1900s. Galvanic skin testing detects sweat on the skin, and more sweat produces better electrical conduction.
In the 1950s, a West German physician and acupuncturist named Reinhold Voll combined acupuncture theory with galvanic skin response technology. He tested the skin along various points with particular attention to the acupuncture meridians.
Galvanic skin response changes are still used in lie detector tests, along with several other measures such as pulse, breathing, and blood pressure.