Galvanic Skin Response


Stress is a physiological condition in which the body becomes excited to face an emergency situation. A number of physiological changes including increase in heart rate, breathing rate etc. occurs during a high stress state. There is a relationship between Stress and the Electrical conductivity of the skin. This is known as Galvanic Skin Response or GSR. Skin conducts electric current like a Resistor used in electronic circuits.

Stress

Stress is a physiological condition in which the body becomes excited to face an emergency situation. A number of physiological changes including increase in heart rate, breathing rate etc. occurs during a high stress state. Adrenaline hormone secreted by the Adrenal glands initiates the process of Fight and Flight that leads to a number of physiological changes in the body. These hormone triggered changes makes the body alert to face the situation. This is mainly due to the activation of Sympathetic nervous system. But after a short period of time, body returns to normal by the activation of the Parasympathetic nervous system. So stress is a natural mechanism to cope up with the changes in the surroundings. In a healthy person, the normal body conditions and stressful conditions are almost balanced. But in some persons, unnecessary feelings, anxiety etc causes frequent stress. This is harmful to the body as well as mind since these persons cannot concentrate in their work or studies. Unnecessary activation of the physiological systems may also leads to health problems including reduced immunity.

Stress and the Electrical conductivity of Skin

Galvanic Skin Response

There is a relationship between Stress and the Electrical conductivity of the skin. This is known as Galvanic Skin Response or GSR. Skin conducts electric current like a Resistor. The resistance of Skin can vary from 25 Kilo Ohms to 2 Mega Ohms depending on the Emotional state (This varies from person to person ).This variation is due to the changes in the permeability of the skin. In a normal fully relaxed person, skin resistance will be around 2 Mega Ohms. This is due to the low permeability of the skin. Skin offers high resistance and restricts the current flow. But if the same person is in stress, his skin resistance reduces to 25 Kilo Ohms or less due to leakage of water from the blood vessels and subsequent sweating. This increases the electrical conductivity of the skin. Thus the electrical conductivity of the skin and Stress are directly related.

In short

Relaxed state – High skin resistance – Low electrical conductivity
Stressed state – Low skin resistance – High electrical conductivity

Thus the Galvanic skin response can be taken as a measure for the level of Stress. Polygraphs, Lie detectors etc.follow this principle.


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