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Biofeedback Monitoring using a Galvanic Skin Response Meter


The GSR meter, or galvanic skin response meter, is a biofeedback monitoring device designed to detect a person's mental state or change of state.

This type of device can be used one to one, with the person so monitored holding one electrode in each hand while the facilitator operates the meter, or solo (as in certain types of self-development counselling), with the person using the meter on himself holding suitably insulated electrodes in one hand.

There are many types of GSR meters on the market today – Ability Meter, Clarity Meter, Psychotechnics GSR Meter, Phoenix Meter and Mindwalker Meter are just a few such models which are available. Computer-based versions, such as the Mark 3.0 and Mark 4.0 Mindwalker meters, have also been developed.

Unlike classical biofeedback where the user is trained to produce a particular desired response, the GSR meter when used as a counselling or study aid is used purely for diagnostic purposes. It assists the facilitator in locating where the area of difficulty is, determining the efficacy of the technique being used or whether a different process or method may be more appropriate in solving the difficulty, and knowing when a desirable outcome has been achieved signalizing a suitable point to end off.

The GSR meter has been widely used for experimental and leading-edge psychotherapy and personal development purposes, although it remains ignored by mainstream therapists.

This paper does not attempt to describe the various practices which use the meter as a diagnostic tool in their various processes and techniques. The focus of this paper instead is to outline the development of the GSR meter, what it measures, and the interpretation of various types of reads and associated phenomena.

This paper was compiled from the content private conversations, emails, online discussions and the author's own personal knowledge, training and experience. Publications have been mentioned where appropriate in the text only for the sake of historical completeness.


Tarchinoff is usually credited with the discovery of the phenomenon of skin resistance in 1888, although the French physician C. S. Fere is also reported to have described a type of GSR meter the same year. Tarchinoff found that when a tiny electric current is passed through the human body via a pair of (usually handheld) electrodes, the amount of electrical resistance of the body varied according to the emotional state of the subject. He developed a primitive GSR meter to research this phenomenon.

In the late 1890s, Wilhelm Wundt used a similar kind of meter in his Leipzig laboratory to measure body electricity. This line of research came to be known as psychophysics.

In 1906 C. G. Jung published an article entitled "Studies in Word Analysis", where he describes using a GSR meter on a subject. Jung read a prepared list of words one by one to the subject while watching for reactions to each word on the meter. Words which the subject found emotionally charged caused a change in body resistance, which showed up as a reaction of the needle on the GSR meter. When a word produced a larger than usual meter response, Jung assumed this to be an indicator of possible areas of mental conflict, which could subsequently be explored in greater depth during the course of therapy. Jung was thus able to adjudicate which areas would be most fruitful for exploration in individual subjects. Jung wrote up his findings on the use of a GSR meter in an article in the Journal of Abnormal Psychology in 1907.

By the 1920s others were conducting follow-up research into the electrical measurement of thought and emotional states. Mary Collins and James Dreaver of the University of Edinburgh published their own findings in a report entitled "Experimental Psychology" in 1926.

The GSR meter remained difficult to use outside the context of the specialist laboratory until advances in valve amplifier technology in the 1930s permitted the development of more sophisticated machines which used amplification, including portable models.

In 1935 Wilhelm Reich at the Psychological Institute, University of Oslo, conducted experiments showing the existence of a bio-electrical charge.

Perhaps unsurprisingly, the principle of the galvanic skin response was also enthusiastically taken up by criminologists, who developed the use of the polygraph. Police forces around the world used the "lie-detector" for many decades. Polygraph lie-detector tests however only register the presence of an emotional reaction, and do not necessarily register a reaction capable of being conclusively interpreted (i.e. proof of guilt at having committed a crime). Furthermore, criminals may not produce any substantial polygraph reactions under questioning, since they often feel no remorse or sense of responsibility for their actions.

In the 1950s Volney Mathison, a chiropractor and electronics expert, developed a type of GSR meter named the electropsychometer, or E-meter. He had been attending a lecture given by L. Ron Hubbard, where Hubbard described a rough specification for an electronic device capable of registering thoughts and emotional charge for use in Dianetic counselling sessions (or auditing as it is called), and set about designing his original prototype, the Mathison Model B. Mathison's early meters were rather complex and subsequent models manufactured for the same purpose by an electronics business run by two brothers in the south of England were of a much simpler design, and thus easier for trainee practitioners to learn to use. The focus became to develop a meter capable of registering emotional and mental responses to specific stimuli, to use for diagnostic purposes, rather than as a lie-detector. Sensitive circuitry was developed to amplify mental reads while damping out, as far as is practicable, pure body electronics. The type of GSR meters used in counselling sessions are much more sensitive to mental phenomena than are the type of galvanometers used in medical fields, which register almost entirely on body reactions.

Parallel to this line of development as a counselling tool, others were working on the use of the GSR meter as a relaxation and meditation tool. Cheap GSR gadgets came into vogue during the 1970s in the wake of the surge in popularity of subjects such as yoga and transcendental meditation. Many of these gadgets however were of little more than curiosity value, and would not have been sensitive or accurate enough to use as a counselling diagnostic monitor, and the subject of biofeedback monitoring became labelled in the minds of the public and media as little more than a passing fad.

Meanwhile, serious work had been done to produce more sophisticated GSR meter models with a greater range of sensitivity and greater ease of use.


The GSR meter is based on the principle of the Wheatstone bridge - a type of ohm meter for measuring changes in electrical resistance.

The nervous system uses electrical impulses which are affected by the person's thoughts, emotions, physical condition etc. The GSR meter passes a tiny electrical carrier wave (approx. 0.5-3.0 volts) through the body, which picks up the fluctuations in resistance caused by the person's overall general mood and emotional reactions to specific stimuli. These changes in resistance are known as the galvanic skin response.

Freud was one of the first to explore the idea that the subconscious holds various repressed negative content, such as irrational fears, motivations, dislikes etc. A person cannot easily move past this subconscious conditioning due to its hidden nature; his thoughts, actions and emotions are coloured by subconscious content impinging upon them. During therapy, this subconscious content can be examined and confronted by the patient, discharging its ability to restrain or affect his behaviour or demeanour. The counsellor or facilitator does not need to waste time hunting at random to get to the root of his client's difficulties, nor does he need to develop superhuman powers of observation to see inside the mind of his client. The GSR meter is capable of assisting him in locating the exact area of emotional charge or difficulty.

The GSR meter is used in conjunction with specific processes with specific desired outcomes. Those specific processes might be a prepared list of questions to locate the main charged areas that needs addressing, or they might be a series of questions run repetitively for the purposes of personal exploration and self-awareness. It is a fruitless exercise hunting around at random for a topic that might be hot, and any such exploration should be done under the guidance of a trained practitioner.

The meter reads on the emotional charge before the client becomes conscious that the question or topic under discussion is so charged. The device has thus been described as a "pre-conscious" meter. Once the client's attention has been directed to the charged area through questioning by the facilitator, the area can be taken up and handled using specific procedures.

Despite the galvanic skin response being a documented phenomenon, there are still those who persist in the belief that the device only registers on sweaty palms caused by anxiety in the subject. Anyone who has witnessed the needle drop several divisions as a reaction to a certain question or item would quickly realise that this reaction would have to signify the production of a great and sudden quantity of sweat! Also, the client's hands wouldn't be able to "unsweat" in order to cause a soaring, rising needle, nor to keep fluctuating in sweatiness sufficiently rapidly to cause other types of meter reactions. It is theoretically possible to use any two points of skin contact using appropriately modified electrodes, but the palms of the hands seem to work best, using cylindrical tin-plated copper electrodes.

Biofeedback research has shown that meditation and relaxation techniques cause a greater degree of resistance, while stress and unpleasant emotions show a lowering of the resistance during such practices. When buried material begins to surface in the mind of the client under therapy, such as that caused by pain or negative emotions, the concomitant tension experienced by the client shows as an increase of skin resistance. Dr. Michael Apter of Bristol University writes about the "Reversal Theory", as he calls this phenomenon, in his book of the same name.

The meter is capable of measuring a far greater span of resistance than is catered for by the needle dial. The GSR meter thus has a control knob which allows the needle to be brought back onto the dial after an increase or decrease of resistance has caused it to hit the pin on the far left or right of the dial respectively. When the needle is at the "Set" marking just to the left of centre of the needle dial, this establishes the client's baseline of skin resistance, which is expressed as a numeric value. The markings surrounding the baseline control on the meter casing are usually numbered 1 to 6 - probably arbitrary values assigned in the early development of the meter. The meter registers a range of just under 480 ohms to approximately 1,000,000 ohms, with a baseline of 2.0 being the resistance of an uninfluenced female body and a baseline of 3.0 being the resistance of an uninfluenced male body.

It is not necessary to know all the technical details of exact ohm values at various baseline positions in order to use the device competently. For the sake of interest, however, they are: 1.0 - 480 ohms, 2.0 - 5,000 ohms, 3.0 - 12,500 ohms, 4.0 - 26,700 ohms, 5.0 - 62,000 ohms, 6.0 - 292,000 ohms and 6.3 - 1,000,000 ohms. It is unusual for the baseline to go to the low and high extremes, with the resistance varying between approximately 5,000 to 15,000 ohms for most people under normal circumstances.

The general level of resistance is a vital indication of a person's general state of case. A person with a lot of mental mass and emotional charge on their case would tend to have a high baseline of resistance. However, it is interesting to note that a person who is so heavily mired in charge to the point of overwhelm tends to have an abnormally low resistance baseline (lower than 2.0). A person in good shape would usually register on average between 2.0 and 3.0.

Environmental factors such as excessively sweaty or very dry hands, uncomfortable temperature extremes, tight clothing, rusty or coated electrodes etc. can cause the phenomenon of "false" baseline values - where the apparent skin resistance is higher or lower than it should be due to physical factors entering in. These would be recognized by an experienced practitioner and handled before session start.

It is possible to adjust the sensitivity setting of the GSR meter so that the swing of the needle is magnified or decreased in order not to have either the needle constantly disappearing off the dial (too much sensitivity) or reads so tiny they are difficult to interpret. The sensitivity is adjusted before each use of the GSR meter, as it varies not only from one person to another, but from time to time.

It must be borne in mind that as the resistance increases, read sizes become proportionally smaller, and increase in size as the resistance comes down. That means that a two inch fall obtained at a baseline level of 2.5 would only appear as a reaction a fraction of an inch in size at a baseline level of 5.0. One particular model of GSR meter has a special circuit to compensate for this phenomenon. One should obviously handle any phenomena causing false baseline values anyway, but when using this particular meter model, a false reading makes the needle far too sensitive to be workable.

Body reactions such as fidgeting, coughing, deep breathing, knocking the cans together, moving the fingers or rubbing the cans on clothing produce needle reactions which a practitioner is trained to recognize. Once the recognition of these have been drilled, and the practitioner has seen for himself the type of reactions produced by purely mental phenomena, he will see that the types of needle movements produced are very distinctly different.

A demonstration that the meter reads on thought and emotion can be carried out by asking the person holding the cans to think of an area of stress in their life. The needle will be seen to fall. Another demonstration is the "pinch test", whereby the person on the cans is asked to recall the moment of the pinch while watching for a fall on the meter. Other reactions can be obtained by thinking of various pleasant and unpleasant experiences and concepts.

Various different meter reads have been identified and described, and anyone becoming expert on the meter and its use would be expected to recognize them and understand what they signify. During a session, the facilitator would not bring the client's attention to the meter or its reads. He would be observing the meter in conjunction with the body language and facial expressions of the client (the "indicators") and using this data to adjudicate what needs to be done next in the session. The client's attention should be focused entirely on the questions and processes, without his attention being unduly drawn to the meter, facilitator or session admin.

A fall in skin resistance during a session signifies an increase in alertness or awareness. This could be a small fall, or it could be a major drop in resistance of several baseline divisions, requiring the practitioner to adjust the baseline position to bring the needle back onto the dial. This phenomenon can be described as a baseline drop, or a blowdown. A blowdown signifies that a very large amount of emotional charge has come off and it is usually accompanied by a realisation or newfound awareness on some area of life.

The size of the read is directly linked not only to how much emotional charge is present in the subject matter at issue but also the degree to which that subject matter is real to the individual. A heavily charged item which has been deeply buried by the individual may not produce a substantial reaction on the meter until other items of which the person is more aware have been addressed and handled. A list of items would thus be prioritised according to the size of the reads. For the purpose of identifying such, a "read" in this context would usually mean the needle had made a motion from left to right of a quarter inch or greater and occurring instantly at the end of the item being spoken.

There are the phenomena of the "tick" (a micro-read of less than about a quarter inch) and the "stop" (where the needle halts moving briefly). These are indicators of subjects which could be charged, and which can be explored via the use of "buttons" (questions designed to find out whether a subject is hot but has been repressed by the client) to see if they develop into a larger read which can be taken up. If they do not, the facilitator should leave the subject matter in question alone as it would not be a profitable area to try and examine at this time.

The GSR meter not only alerts the facilitator to the fact that emotional charge is present, it also lets him know when there is no charge on the subject to take up. Clients get very upset when a facilitator evaluates for them (tells them what to think about themselves), and taking up a null (non-reading) item or question certainly comes under the definition of evaluation. When the needle continues doing whatever it is doing despite questioning by the facilitator, there is no charge on the subject matter that is sufficiently real to the client to address at that point in time. The facilitator should therefore be sure never to attempt to address items which merely show a null needle.

A rising needle means that the person has emotional charge on the area which they are mentally resisting or protesting, and which he does not want to confront. Once this material has been confronted and discharged, the baseline level will come back down. It can also be a sign that something has gone on for too long, and the facilitator would check this possibility with the client and conduct the appropriate handlings, if the needle continued to rise.

There are of course other categories of reads which would be seen while performing specific areas of case address, which are beyond the scope of this paper. There are also other needle actions and general meter behaviour that would tend to be seen on various states of case.

It is worth looking at the client's general needle pattern. If the needle tends to move around smoothly, except for responding to the facilitator's questions and the client's answers, this pattern is described as a clean needle. The needle can be "dirty" (a pattern of jerky, ticking movements) and this can signify various things including the client not feeling present in the session or in good communication with the facilitator, as well as certain case phenomena. Upon seeing a dirty needle the facilitator would ask the client what his attention is on in order to clean the needle and continue with the procedure.

Some people have a very loosely moving needle, whereas others' needle patterns tend to be rather tight and don't move around quite so easily. When a person's attention is fixed on something, this can cause the needle to appear tight. It is notable that as a process progresses, the needle becomes looser until eventually a free or floating needle will be seen. This is a very distinctly recognisable needle action where the needle just idles back and forth without responding to anything the facilitator says. It is usually accompanied by some sort of realisation on the part of the client, who would usually be very happy at this point, as something would have departed or released on his case. These indications are what are known as the end phenomena of a process, and would be the point where the facilitator would end off.

In some instances the needle can float so widely as to be wider than the needle dial, so that the facilitator would have to adjust the baseline control at either end of the needle swing. Such a "floating baseline" signalizes a huge win or realisation. On seeing this meter phenomenon, or a floating needle that just persists and persists, it would be unlikely that any more case material would be available to handle that day. The only thing that can be done under such circumstances is to end off and let the client enjoy his win, and until he feels that he is ready to do more.

Over the course of therapy the client's meter phenomena tend to change. His baseline level, if high or low, would eventually come into range (between 2.0 and 3.0). His needle, if tight or dirty, would tend to loosen and smoothen out. Areas of case address which were repressed and thus difficult to get a read on, would start to show a live and responsive needle under questioning. Even some medical professionals have corroborated the fact that people who have had much of this type of therapy have a rather different EEG pattern to persons who have never undergone such therapy.

I hope you enjoyed this short introduction to the GSR meter.

Best regards.
Gwyneth Wesley Rolph
© 2009