galvanic skin response

A change in the ability of the skin to conduct electricity, caused by an emotional stimulus, such as fright.

A transient change in certain electrical properties of the skin, associated with the sweat gland activity and elicited by any stimulus that evokes an arousal or orienting response. Originally termed the psychogalvanic reflex, this phenomenon became known as the galvanic skin response. Electrodermal response (EDR) has replaced galvanic skin response as the collective term.

The skin of a relaxed person has a low electrical conductance (high resistance), and the skin surface is some 40 mV negative with respect to interior tissues. Sweat gland activity changes these electrical properties by increasing skin conductance and by changing the balance of positive and negative ions in the secreted fluid.

Tonic skin conductance varies with psychological arousal, rising sharply when the subject awakens and rising further with activity, mental effort, or especially stress. Phasic skin conductance responses are wavelike increases in skin conductance that begin 1–2 s after stimulus onset and peak within about 5 s. The amplitude of the skin conductance response varies with the subjective impact of the eliciting stimulus, which in turn varies with the intensity of the stimulus, its novelty or unexpectedness for the subject, and its meaning or signal value. Aroused subjects display spontaneous skin conductance responses, generated apparently by mental events or other internal stimuli; their frequency, like the tonic skin conductance level, increases with the level of arousal.

Electrodermal responses are measured in studies of emotion and stress, conditioning, habituation, and cognitive processing, that is, when it is desired to assess the differential or changing impact of a series of stimuli. See also Electroencephalography; Lie detector; Sympathetic nervous system.

In marketing research, clinical measurement of a subject's response to stimuli, such as an advertisement, in terms of changes in skin resistance to electrical current; also called psychogalvanic skin response or sweaty palms. Theoretically, the greater the change in resistance, the more positive the subject's reaction to the stimuli. The validity of this technique has been much disputed, particularly because there is no way of knowing for sure that the stimulus provided by the researcher (the advertisement) was the cause of the response. Its proponents argue that it is more objective than research that relies on voluntary responses like interviews or surveys. See also eye movement analysis.

A reaction to certain stimuli as indicated by a change in the electric resistance of the skin. The GSR is used in some polygraph examinations.

Response of the skin to the passage of a small electric current. The ease with which the current flows between two points on the skin can be used to indicate stress. When a person is tense or emotional, the sweat glands become more active, increasing moisture on the skin; this allows the electric current to flow more readily. The response may also be used in relaxation training: information about the galvanic skin response is fed back aurally or visually to the subject who can, with practice, learn to increase or decrease sweating on the skin by learning to relax or tense muscles (see biofeedback).

A sample GSR signal of 60 seconds.

Galvanic skin response (GSR), also known as electrodermal response (EDR), psychogalvanic reflex (PGR), or skin conductance response (SCR), is a method of measuring the electrical resistance of the skin. There has been a long history of electrodermal activity research, most of it dealing with spontaneous fluctuations.

Contents 1 Description 2 History 3 Uses 4 See also 5 Notes 6 References 7 External links

Description

The device measures electrical resistance between 2 points, and is essentially a type of ohmmeter. The two paths for current are along the surface of the skin and through the body. Active measuring involves sending a small amount of current through the body.

Due to the response of the skin and muscle tissue to external and internal stimuli, the resistance can vary. When correctly calibrated, the GSR can measure these subtle differences. There is a relationship between sympathetic activity and emotional arousal, although one cannot identify the specific emotion being elicited. The GSR is highly sensitive to emotions in some people. Fear, anger, startle response, orienting response and sexual feelings are all among the emotions which may produce similar GSR responses. These reactions have allowed lie detectors to have some success.

History

The scientific study of GSR began in the early 1900s. One of the first references to the use of GSR instruments in Psychoanalysis is the book by C. G. Jung entitled Studies in Word Analysis, published in 1906.^[1] Wilhelm Reich also studied GSR in his experiments at the Psychological Institute at the University of Oslo in 1935-6 to confirm the existence of a bio-electrical charge behind his concept of vegetative, pleasurable 'streamings.'^[2] GSR was used for a variety of types of research in the 1960s through the late 1970s, with a decline in use as more sophisticated techniques (such as EEG and MRI) replaced it in many areas of psychological research. GSR still sees limited use today, as it is possible to use with low-cost hardware (galvanometer).

Uses

GSR measurement is one component of polygraph devices and is used in scientific research of emotional arousal.

The E-meter, which is used by the Church of Scientology, is a GSR measurement device.

GSR measurement is also becoming commonplace in hypnotherapy and psychotherapy practice where it can be used as a method of detecting depth of hypnotic trance prior to suggestion therapy commencing. When traumatic material is experienced by the client (for example, during hypnoanalysis), immediate changes in galvanic skin response can indicate that the client is experiencing emotional arousal. It is also used in behavior therapy to measure physiological reactions such as fear.

See also

• Electroacupuncture
• Affective computing
• Biosignal

Notes

1. ^ The Biofeedback Monitor
2. ^ Reich, W. 'Experimentelle Ergebnisse ueber die electrische Funktion von Sexualitat und Angst' (Sexpolverlag, Copenhagen, 1937). Translated as 'Experimental investigation of the electrical function of sexuality and anxiety' in J. of Orgonomy, Vol. 3, No. 1-2, 1969.

References

• Conesa, J. (1995). Electrodermal palmar asymmetry and nostril dominance. Perceptual and Motor Skills, 80, 211-216

External links

• University of Kuopio page on GSR Use
• Cornell GSR Class Project
• Instructions on making and using a GSR sensor

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