To understand galvanic skin response (GSR), you must review the physiological properties of the biggest organ of the body – the skin.
The skin is an incredibly multifaceted organ. It is smooth to touch and lovely on the eye, but it also assists in regulating various bodily functions.
The skin acts as the primary interface between environment and organism. Alongside other organs in the body, it manages bodily functions like sensing and perception, basal temperature, and the immune system.
Sensing & Perception – The skin is essentially a sensory organ. It consists of an expansive network of nerve cells that perceive and transmit environmental changes based on the actions of receptors for pain, pressure, and temperature.
Thermo-Regulation – The skin manages body temperature by controlling peripheral blood circulation, sweat secretion, and piloerection (goose pimples or goosebumps). Ideally, it maintains your body at a constant 98.6 degrees.
Immune System – The skin acts as a protective wall separating the body from the external surroundings and dangers – chemical agents, radiation, mechanical pressure and impacts, micro-organisms, and temperature variations. With a robust immune system, the skin can heal itself.
The human body consists of around 3 million sweat glands. Sweat gland density contrasts markedly throughout the body, highly concentrated on the cheeks and forehead, fingers, palms, and feet. When sweat glands are elicited, they become more functional and start exuding moisture through the skin. By adjusting the balance of negative and positive ions in the secreted liquid, electrical current can flow more easily, leading to detectable electrodermal response variations. Increased skin conductance = decreased skin resistance.
This variation in skin conductance is referred to as Galvanic Skin Response (GSR).
How does it function?
Galvanic skin response technology goes by many names, including skin conductance response (SCR), skin conductance level (SCL), electrodermal level (EDL), electrodermal activity (EDA), or electrodermal response (EDR). This phenomenon generally happens when the system is kindled following a stimulus. It’s usually a measure of somebody’s emotional state intensity, also called emotional arousal.
The degree of emotional arousal varies depending on the environment one is in – if you find something joyful, sad, threatening, scary, or even emotionally pertinent, then the ensuing difference in emotional response increases activity in the eccrine sweat gland.
It’s worth noting that both negative (‘sad’ or ‘threatened’) and positive (‘joyful’ or ‘happy’) stimuli can lead to emotional arousal, which can, in turn, raise skin conductance.
Although sweat excretion plays a significant role in sensory discrimination and thermoregulation, fluctuations in skin conductance can activate by an emotional stimulus: the arousal levels directly correspond to the skin conductance.
The concentration of eccrine sweat glands greatly varies throughout the body but can be found in large amounts in the foot and hand areas (200-600 sweat glands for every cm2).
The conscious cannot control sweat excretion and other alterations affiliated with skin conductance. They moderate through sympathetic control, which influences certain characteristics of human behavior and emotional and cognitive states.
Sympathetic activity is linked with bodily autonomic functions like increased blood pressure, heart rate, and sweating. Skin conductance provides a better understanding of autonomous emotional regulation.
What You Should Know
Given how GSR measurements function by sensing the variations in electrical activity arising from fluctuations in sweat gland activity, the electrodes placed on the skin’s surface must be responsive to these fluctuations and capable of relaying the acquired data to the recording machine.
Many contemporary GSR electrodes have a silver-chloride (Ag/AgCl) connection point that engages with the skin. Ag/AgCl electrodes are sought-after because they are robust, inexpensive, and safe for humans. Most importantly, they can accurately relay the signal resulting from the electrical(ionic) activity.
Other electrodes come prepacked with ionic gel that can enhance the reliability of the signal, or ionic gel can directly be applied to the skin’s surface to attain the same effect. The signal transmits via the electrode to the lead wire that transports the data to the GSR machine.
Various GSR sensors support varying transmission mediums, and the choice of which device to acquire for your practice depends on the type of research you’re doing and your patients.
What Does Galvanic Skin Response Measure?
Skin conductance baseline level is known as tonic conductance. This conductance reading varies for everybody but is often between 10 – 50 tiny packets of conductance called microsiemens. Tonic skin conductance readings are also different depending on the individual’s psychological condition.
Although tonic conductance is a standard reading, phasic conductance amplitudes and latency result from the body reacting to stimuli.
Phasic fluctuations can be detected when the sweat ducts of the skin fill in following a stimulus. When the sweat is absorbed or accumulated by the skin, conductance reverts to tonic levels. When there are considerable variations in GSR functionality following a stimulus, this phenomenon is called an Event-Related Skin Conductance Response (ER-SCR). Such reactions, also called GSR peaks, can offer valuable info concerning emotional stimulation.
By using skin conductance measurements, or GSR peaks, adding quantitative information to emotional stimulation research becomes easier. With more information and data, uncovering new protocols for your patients becomes possible.
The intensity of emotional stimulation can be detected by gauging GSR (along with other sympathetic responses). It is noteworthy because its data is obtained directly from inside the body. Thus, the readings and measurements acquired are unbiased at how the body responds when exposed to certain stimuli.
Since consciousness filters the thoughts one has, it’s challenging to accurately determine what’s going on inside the body. With GSR, you can circumvent these filters and determine the body’s response with high precision.
Telling The Truth
The most renowned galvanic skin response device is in the lie detector examination, officially referred to as the polygraph machine. Other than gauging blood pressure, respiration rate, and heart rate, the polygraph machine gauges GSR response as questions keep going on. A trained polygrapher is qualified to decipher the reactions to the questions.
First off, the polygrapher will ask obvious questions that are either false or true, like “Do you live in this state?” to determine a baseline measurement. Additional questions are asked, and the measurements are contrasted to the base reading to establish if the individual is telling the truth.
Other applications of GSR enable you to determine how your patient’s body is responding without interference from conscious filters. It is an effective method for determining exactly how the body changes when exposed to certain stimuli.
Advantages Of Galvanic Skin Response And Biofeedback
GSR, along with other similar readings, falls under Biofeedback. Equipment that collects biofeedback data can assist you in gaining a greater understanding of the body’s physiological happenings. The concept behind Biofeedback is that by monitoring the responses elicited, people can train themselves to manage their sympathetic responses.
The most crucial thing to note with Biofeedback is that it needs active engagement and participation. You can think of biofeedback pain management as a training process instead of therapy that assists your patients to have a better understanding of their health issues, which can subsequently increase coping ability and well-being.
BioScan Uses Galvanic Skin Response
With minimal cleanup and prep times, a BioScan system used to measure skin conductivity is non-intrusive as the procedure is conducted by placing two electrodes on the skin’s surface. It makes taking GSR measurements efficient and comfortable for patients compared to other techniques.
When you use BioScan as the basis of your data collection, you can detect and scan the skin’s ionic activity against a range of psychological or physiological signals in real-time. Combine several data streams and apply computations with the BioScan software to detect connections between emotional or physical stimuli and skin conductance stimulation level.