The Galvanic Skin Response also known as GSR, is a process to measure the electrical conductance of the skin in a human as it varies with changes in the environment around every individual. This is a basic situation where any individual is subjected to be aroused or excited, here the moisture levels in the skin vary causing its electrical conductance to change which we then capture. This takes place due to the fact that sweat glands in us are controlled by the nervous system, and any change in conductance can indirectly be a measure of the mental activity that is happening in that moment.

How does it work then?

Well, this can’t be any rocket science but in order to measure the electrical resistance, a constant voltage should be applied and the skin conductance can then be calculated with the help of Ohm’s Law by measuring the flow of current. The device applies a small voltage through the skin which otherwise cannot be perceived by humans but can be detected through amplification.

On a lighter note the more common method of measuring the skin conductance using an external electrical stimuli as opposed to the lesser used method of finding an internally generated voltage on the skin in an initial base level is called the Skin Conductance Level. Every individual has a different SCL that ranges from 10 – 50 µS. The tool that measure a galvanic skin Response are often referred to as feedback instruments, this in part because of how the response is generated or detected. Suppose the response is measured “actively,” then a gentle electric jolt is passed through the body of the test subject to measure its conductivity. In case of a passive test measures the current is generated by the person’s body itself. Here the feedback is what constitutes the measured galvanic skin response of an individual.

Why is it done?

You could now be a little curious to know why do we measure the galvanic skin response, what is it for? Well, we say this can be an important element of certain psychotherapy treatments, as well as behavioral therapy in individuals. There is an established connection between the stress levels and anxiety levels to the response of the skin when these electric waves are passed.

The most well-known traditional use of this test is to measure the response as a part of a polygraph or the ‘lie test’. This includes various parameters of the body’s reaction in which GSR is one which are recorded when a person tells a lie. In terms of science and psychology, knowingly stating a falsehood is considered stressful and unnatural. Therefore a changes in the electrical conductivity of the skin, as well as changes in breathing or the heartbeat, and even perspiration, are body’s responses to the situations of stress of lying.

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