The Story of the e-meter Part 5: Is It Fit for *Any* Purpose?


MITs Galvactivator – A Wearable GSR Meter

Volney Mathison’s electropsychometer measured a real phenomenon called Galvanic Skin Response (GSR).

Whenever you experience something that is psychologically arousing, your  eccrine sweat glands are activated, which results in a ‘micro-sweat’.

This means that when you experience a strong emotion, are performing a mentally demanding task, or are just startled your skin resistance will drop.

GSR changes happen in the same way that the pupils of your eyes contract in bright light, or your heart rate increases when you are startled.

Because GSR is not under conscious control real-time measurements might feasibly provide an objective measure of a person’s psychological state.

Volney Mathison made reasonable claims for his e-meter. He presented it as an accurate instrument to measure GSR, which could be useful in psychological therapy.

To access these claims, lets compare the e-meter with a device designed by students of the Massachusetts Institute of Technology (MIT) specifically to measure and indicate GSR – the “Galvactivator“.

Basic Design

GSR is measured by passing a small, constant current through the body and showing the result on a meter. If you are using an old-fashioned galvanometer with a needle, the needle will detect GSR when it indicates a higher voltage by moving to the right.

Volney Mathison’s prototype added a small amplifier, to boost the current before it enters the meter. This made the device easier to use because the amount of amplification can be turned up or down to adjust it for different people (who have different ranges of skin resistance).

The MIT Galvactivator contains all of the same components, but is built into a tight-fitting glove and uses the variable light output from an LED on the back to indicate the level of GSR.


Two electrodes are needed  in a GSR meter to pass an electrical current through the subject’s body. emeter cansThe palms of the hands and the soles of the feet are the best areas of the body t0 put them, because these places have the highest concentrations of eccrine sweat glands.

Mathison originally strapped electrodes to the soles of his subject’s feet. This proved impractical, so he adopted hand-held electrodes -which are still used by Scientology’s e-meter. These were originally empty soup cans (which is why they are still referred to as “cans”) and while the latest versions are more stylish (and expensive) they are still the same basic size and shape.

This is a poor design for a GSR meter because the readings can be affected by how tightly the cans are held. Also, subjects can learn to unconsciously (or deliberately) manipulate the readings by varying their grip.

In contrast, the electrodes in MITs Galvactivator are small, and built into the close-fitting glove, so the subject cannot manipulate them in any way.


The electronic circuits in the two devices are functionally identical. Resistance is measured using a circuit called a “Wheatstone Bridge” and the signal passed through an adjustable amplifier.


MathisonE-meters use an old-fashioned mechanical galvanometer to indicate their readings. While this gives an illusion of precision, the range of GSR reactions is quite narrow. The simple LED used on the MIT Galvactivator is enough to indicate whether you are relaxed, highly aroused, or somewhere in between.

This is where Mathison’s design, and the design used in Scientology’s e-meters diverges. Mathison used standard galvanometers. The ones used in Church of Scientology e-meters are (uniquely) undamped.

Standard galvanometer mechanisms are carefully designed to be exactly ‘stiff ‘enough that they move freely, but do not react to every tiny, transient change and provide a steady reading.This is comparable to the function of  shock absorbers / dampers on a car – they soak up all the bumps in the road to provide a smooth ride.

Because the galvanometers used in Scientology’s e-meter’s are not damped  typically react misleadingly to the slightest changes  (for example, the subject shifting their grip on the cans because their hands are tired). It’s like driving a car without shock absorbers / dampers – it bounces about all over the place.

The reactions of the LED on the MIT Galvactivator are electronically damped, so it provides a much more accurate indication of GSR, free of this kind of artefact.

Interpretation of Readings

auditorUntil Scientologists reach a advanced level, they are not permitted to see their own meter readings. They have to rely on their ‘auditor’ to tell them them the truth about how the meter is moving. Even if the auditor is honest and sincere, this is still problematic.

Although the auditing process  takes place in a private room, the proceedings are still subject to complex social effects. Both parties enter the room with expectations provided by their Scientology training.

Both parties hope to produce the expected results in order to impress their peers and advance in the organisation. Consequently, the subject may follow subtle non-verbal cues unconsciously provided by the auditor to insure ‘success’.

There is ample scope for this kind of self-deception because (thanks to the poor electrical contact provided by the ‘cans’ and the undamped galvanometer previously mentioned) the e-meter is prone to random movements that have nothing to with GSR. In this situation, expectation bias  comes into play.

Auditors may unconsciously select those readings which conform to their expectations, and ignore the others (designating them as ‘false reads’). In other words, auditors tend to see what they have been trained to expect (and want to see). The chaotic meter movements that occur during a real session give the plenty to choose from.

The electrodes on the  MIT Galvactivator are secure, and the LED is electronically damped – so it is free from effects that have nothing to do with GSR. It can be used in everyday life, so there is no associated social pressure. Finally, the display is quite unambiguous – so it is more difficult to fall prey to expectation bias.

E-meter Vs Galvacticator

Used properly, the MIT Galvactivator can provide an accurate, real-time indication of your GSR.

The e-meter provides a very poor indication of GSR because the reading can be affected by things which have nothing to do with skin resistance – principally changes in the subject’s grip on the cans, and random readings due to its undamped galvanometer.

The Limitations of GSR Measurement

The MIT Galvactivator demonstrates the limitations of GSR measurement. It can indicate if the subject is relaxed, highly aroused, or somewhere in between. It cannot read their mind. If you are introduced to someone wearing a Galvactivator, and the LED lights up, it could mean almost anything. For example:

  • They like you
  • They are repelled by you
  • They just had a pleasant thought
  • They just had an unpleasant thought
  • They thought they saw a spider
  • They like the wallpaper
  • They loathe the wallpaper

All that GSR readings can tell you is whether or not someone is psychologically aroused. They can’t tell you why. This is why mainstream therapists never adopted it – it does not tell them anything that they can easily find out in simple conversation.

The inferior design of the e-meter means that it cannot even say this much.


hubbard emeterThe charged social setting in which Scientology’s e-meter is deployed (an auditing session) and its inaccuracy mean that is not used as a measuring instrument at all.

Its real function is as a pseudoscientific prop, to be  used during the session to validate the Scientology concepts that are explored there and encourage further fantasy.

In practice, its unpredictable output means whatever the auditor wants it to mean – and if he wants it to reveal the subjects ‘past lives’, that is what it will do.

Volney Mathison developed a reasonably good GSR meter. Unfortunately, real-time measurement of GSR has no practical use in psychotherapy. Mathison’s equipment was good, but therapeutic claims were pseudoscientific.

L Ron Hubbard has Mathison’s meter modified (with an undamped galvanometer) so that it was no longer fit for purpose. Then, he attributed this simple electrical device with the power to  read minds, detect lies, reveal crimes and other unlikely attributes. He rationalised these claims with extensive ‘Scientology theory’ which are complete fantasy.

If you are interested in the phenomenon of GSR, try the MIT Galvactivator. It is easier to use than the e-meter, a great deal cheaper, and comes free from from any ideological baggage or social pressure.

In the next part of this series, we will examine how Hubbard acquired Mathison’s e-meter, and what use he made of it.


One thought on “The Story of the e-meter Part 5: Is It Fit for *Any* Purpose?

  1. Minor error, the meter mechanism is damped in an e-meter. The degree of damping and the period of the mechanism is carefully controlled. Electronically you can speak of under-damped, critically damped and over-damped needle mechanisms. The e-meter is in the category of under-damped but it is not completely undamped. If it were it would never stop swinging at all.

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s