E-meter

The E-meter is a device for displaying and/or recording the electrodermal activity (EDA) of a human being. The device is used frequently for auditing in Scientology and divergent groups. The efficacy and legitimacy of Scientology's use of the E-meter has been subject to extensive debate and litigation and in accordance with a federal court order, the Church of Scientology now publishes disclaimers in its books and publications declaring that the E-meter "by itself does nothing" and that it is used specifically for spiritual purposes.

Electrodermal activity measuring devices similar to the Scientology E-meter have historically been used by counselors of psychology and psychoanalysis. Such devices have been used as a research tool in many human studies, and as one of several components of the Leonarde Keeler's polygraph (lie detector) system, which has been widely criticized as ineffective or pseudoscientific by legal experts and psychologists.

Electrodermal activity (EDA) refers to the changing electrical charges observed on the surface of the skin. EDA meters were first developed in 1889 in Russia, and psychotherapists began using them as tools for therapy in the 1900s.

Volney Mathison (chiropractor, radio engineer, psychologist, and hypnotist) built an EDA meter based on a Wheatstone bridge, a vacuum tube amplifier, and a large moving-coil meter that projected an image of the needle on the wall. He patented his device in 1954 as an electropsychometer or E-meter, and it came to be known as the "Mathison Electropsychometer". In Mathison's words, the E-meter "has a needle that swings back and forth across a scale when a patient holds on to two electrical contacts". Mathison recorded in his book, Electropsychometry, that the idea of the E-meter came to him in 1950 while listening to a lecture by L. Ron Hubbard:^p. 64

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