Electrodermal activity: Difference between revisions

{{shortShort description|The property of the human body that causes continuous variationVariation in the electrical characteristicsresponse of the skin}}

'''Electrodermal activity''' ('''EDA''') is the property of the human body that causes continuous variation in the electrical characteristics of the [[Human skin|skin]]. Historically, EDA has also been known as '''skin conductance''', '''galvanic skin response''' ('''GSR'''), '''electrodermal response''' ('''EDR'''), '''psychogalvanic reflex''' ('''PGR'''), '''skin conductance response''' ('''SCR'''), '''sympathetic skin response''' ('''SSR''') and '''skin conductance level''' ('''SCL'''). The long history of research into the active and passive electrical properties of the skin by a variety of disciplines has resulted in an excess of names, now standardized to '''electrodermal activity''' ('''EDA''').<ref name=Boucsein2012P02>{{cite book |last1=Boucsein |first1=Wolfram |title=Electrodermal Activity |url=https://books.google.com/books?id=6N6rnOEZEEoC&pg=PR4 |date=2012 |publisher=Springer Science & Business Media |isbn=978-1-461-41126-0 |page=2 |access-date=20 October 2015}}</ref><ref>{{Cite journal|url = http://nro.sagepub.com/content/8/2/132.abstract|title = Book Review: Electrodermal Responses: What Happens in the Brain|last = Critchley|first = Hugo D.|date = April 2002|journal = [[The Neuroscientist]]|doi = 10.1177/107385840200800209|pmid = 11954558|access-date = 15 April 2015|pages = 132–142|quote = Electrodermal activity (EDA) is now the preferred term for changes in electrical conductance of the skin, including phasic changes that have been referred to as galvanic skin responses (GSR)|volume = 8|issue = 2|s2cid = 146232135}}</ref><ref>{{Cite book|title = Electrodermal Activity|url = https://books.google.com/books?id=0hXrBwAAQBAJ|publisher = Springer Science & Business Media|date = 2013-04-17|isbn = 9781475750935|first = Wolfram|last = Boucsein|page = 1}}</ref>

The traditional theory of EDA holds that skin resistance varies with the state of [[sweat gland]]s in the skin. Sweating is controlled by the [[sympathetic nervous system]],<ref>{{Cite book | last1 = Martini | first1 = Frederic | last2 = Bartholomew | first2 = Edwin | title = Essentials of Anatomy & Physiology | publisher = [[Benjamin Cummings]] | location = San Francisco, California | year = 2001 | page = 263 | isbn = 978-0-13-061567-1 }}</ref> and skin conductance is an indication of psychological or physiological [[arousal]]. If the sympathetic branch of the [[autonomic nervous system]] is highly aroused, then sweat gland activity also increases, which in turn increases skin conductance. In this way, skin conductance can be a measure of emotional and sympathetic responses.<ref>{{cite book|last=Carlson|first=Neil|title=Physiology of Behavior|year=2013|publisher=Pearson Education, Inc.|location=New JerseyYork City|isbn=978-0-205-23939-9}}</ref> More recent research and additional phenomena ([[Electrical resistance and conductance|resistance]], [[Electric potential|potential]], [[electrical impedance|impedance]], electrochemical skin conductance, and [[admittance]], sometimes responsive and sometimes apparently spontaneous) suggest that EDA is more complex than it seems, and research continues into the source and significance of EDA.

In 1849, [[Emil du Bois-Reymond|Dubois-Reymond]] in [[Germany]] first observed that human skin was electrically active. He immersed the limbs of his subjects in a [[zinc sulfate]] solution and found that electric current flowed between a limb with muscles contracted and one that was relaxed. He therefore attributed his EDA observations to muscular phenomena.<ref name=Boucsein2012P03>{{cite book|last1=Boucsein|first1=Wolfram|title=Electrodermal Activity|date=2012|publisher=Springer Science & Business Media|isbn=9781461411260|page=3|url=https://books.google.com/books?id=6N6rnOEZEEoC&pg=PA3|access-date=16 April 2015}}</ref> Thirty years later, in 1878 in Switzerland, Hermann and Luchsinger demonstrated a connection between EDA and sweat glands. Hermann later demonstrated that the electrical effect was strongest in the palms of the hands, suggesting that sweat was an important factor.<ref name=Boucsein2012P04>{{cite book|last1=Boucsein|first1=Wolfram|title=Electrodermal Activity|date=2012|publisher=Springer Science & Business Media|isbn=9781461411260|page=4|url=https://books.google.com/books?id=6N6rnOEZEEoC&pg=PA4|access-date=16 April 2015}}</ref>

The scientific study of EDA began in the early 1900s. One of the first references to the use of EDA instruments in [[psychoanalysis]] is the book by [[C. G. Jung]] entitled ''Studies in Word Analysis'', published in 1906.<ref>{{Cite web|url = http://www.sonoma.edu/users/d/daniels/junglect.html|title = Notes on Carl Gustav Jung|access-date = 4 April 2015|website = Sonoma State University|publisher = Sonoma State University|last = Daniels|first = Victor|quote=By 1906 [Jung] was using GSR and breath measurement to note changes in respiration and skin resistance to emotionally charged worlds. Found that indicators cluster around stimulus words which indicate the nature of the subject's complexes...Much later L. Ron Hubbard used this approach in Scientology's "auditing," using the "e-meter" (a galvanic skin response indicator) to discern the presence of complexes.}}</ref><ref>[http://www.trans4mind.com/transformation/gsr.htm The Biofeedback Monitor] {{webarchive|url=https://web.archive.org/web/20080915112040/http://www.trans4mind.com/transformation/gsr.htm |date=2008-09-15 }}</ref> Jung and his colleagues used the meter to evaluate the emotional sensitivities of patients to lists of words during [[Word Association#Psychology|word association]].<ref>{{cite news|title=You can learn control of how your skin talks|url=https://www.newspapers.com/newspage/61192107/|access-date=8 April 2015|agency=The San Bernardino County Sun|publisher=The San Bernardino County Sun|date=October 11, 1977|location=San Bernardino, California|page=12|quote=Current research using the skin's electrical activity as a communications medium between patient and therapist looks promising in such stress problems as drug abuse, alcoholism, neuroses and other tension states.}}</ref><ref>{{cite book|last1 = Binswanger|first1 = L.|editor1-last = Jung|editor1-first = Carl|title = Studies in Word-Association|date = 1919|publisher = Moffat, Yard & company|location = New York, NY|pages = 446 et seq|chapter-url = https://archive.org/stream/studiesinwordass00jung#page/446/mode/2up/search/psychogalvanic|access-date = 30 March 2015|chapter = XII}}</ref> Jung was so impressed with EDA monitoring, he allegedly cried, "Aha, a looking glass into the unconscious!"<ref name=":1">{{cite news|last1 = Brown|first1 = Barbara|title = Skin Talks -- And It May Not Be Saying What You Want To|url = https://www.newspapers.com/newspage/22744127/|access-date = 8 April 2015|agency = Idaho State Journal|publisher = Field Enterprises, Inc.|date = November 9, 1977|location = Pocatello, Idaho|page = 32}}</ref> Jung described his use of the device in counseling in his book, ''[[Carl Jung publications|Studies in Word Association]]'', and such use has continued with various practitioners.<ref>{{Cite web|url = http://www.mind-development.eu/jung.html|title = Carl Jung & Jungian Analytical Psychology|access-date = 9 April 2015|website = Mind Development Courses|last = Mitchell|first = Gregory}}</ref>

By 1972, more than 1500 articles on electrodermal activity had been published in professional publications, and today EDA is regarded as the most popular method for investigating human [[psychophysiological]] phenomena.<ref name="Boucsein2012P07">{{cite book|last1=Boucsein|first1=Wolfram|title=Electrodermal Activity|date=2012|publisher=Springer Science & Business Media|isbn=9781461411260|page=7|url=https://books.google.com/books?id=6N6rnOEZEEoC&pg=PR4|access-date=10 April 2015}}</ref> As of 2013, EDA monitoring was still on the increase in clinical applications.<ref>{{cite journal|last1=Ogorevc|first1=Jaka|last2=Geršak|first2=Gregor|last3=Novak|first3=Domen|last4=Drnovšek|first4=Janko|title=Metrological evaluation of skin conductance measurements|journal=Measurement|date=November 2013|volume=46|issue=9|pages=2993–3001|doi=10.1016/j.measurement.2013.06.024|bibcode=2013Meas...46.2993O }}</ref>

Human extremities, including fingers, palms, and soles of feet display different bio-electrical phenomena. They can be detected with an EDA meter, a device that displays the change in [[electrical conductance]] between two points over time. The two current paths are along the surface of the skin and through the body. Active measuring involves sending a small amount of current through the body.{{Citation needed|date = April 2015}}

There is a relationship between emotional arousal and [[parasympathetic nervous system|sympathetic]] activity, although the electrical change alone does not identify which specific emotion is being elicited. These autonomic sympathetic changes alter sweat and blood flow, which in turn affects GSR and GSP (Galvanic skin potential). The amount of sweat glands varies across the human body, being highest in hand and foot regions (200–600 sweat glands per cm2cm²).<ref name="What is GSR"/> The response of the skin and muscle tissue to external and internal [[Stimulus (physiology)|stimuli]] can cause the conductance to vary by several [[siemens (unit)|microsiemens]]. A correctly calibrated device can record and display the subtle changes.<ref name="multiple">{{cite web |last=Pflanzer |first=Richard |title=Galvanic Skin Response and the Polygraph |url=http://www.vhlab.umn.edu/~bmen3701/Documents/Biopac9.pdf |publisher=BIOPAC Systems, Inc. |access-date=18 August 2017 |archive-url=https://web.archive.org/web/20141218083036/http://www.vhlab.umn.edu/~bmen3701/Documents/Biopac9.pdf |archive-date=18 December 2014 |url-status=dead}}</ref>

EDA reflects both slow varying ''tonic'' sympathetic activity and fast varying ''phasic'' sympathetic activity. Tonic activity can be expressed in units of electrodermal level (EDL or SCL), while phasic activity is expressed in units of electrodermal responses (EDR or SCR).<ref name="Boucsein 2012">{{Cite book|last=Boucsein|first=Wolfram|url=http://link.springer.com/10.1007/978-1-4614-1126-0|title=Electrodermal Activity|date=2012|publisher=Springer US|isbn=978-1-4614-1125-3|location=Boston, MA|language=en|doi=10.1007/978-1-4614-1126-0}}</ref>

Phasic changes (EDR) are short-lasting changes in EDA that appear as a response to a distinct stimulus. EDRs can also appear spontaneously without an observable external stimulus. These types of EDRs are referred to as “nonspecific"nonspecific EDR”EDR" (NS.EDR).<ref>{{Cite journal|last=Society for Psychophysiological Research Ad Hoc Committee on Electrodermal Measures|date=August 2012|title=Publication recommendations for electrodermal measurements: Publication standards for EDA|url=http://doi.wiley.com/10.1111/j.1469-8986.2012.01384.x|journal=Psychophysiology|language=en|volume=49|issue=8|pages=1017–1034|doi=10.1111/j.1469-8986.2012.01384.x|pmid=22680988|s2cid=17713243 |doi-access=free}}</ref> The phasic SCREDR is useful when investigating multifaceted attentional processes.<ref>{{Cite book |author1=Cacioppo, John T. |author2=Tassinary, Louis G. |author3=Berntson, Gary G. |url=https://www.worldcat.org/oclc/166506595 |title=Handbook of psychophysiology |date=2007 |publisheredition=Cambridge3rd University Press|otherslocation=CacioppoCambridge, JohnEngland T.,|publisher=Cambridge Tassinary,University LouisPress G., Berntson, Gary G.|isbn=978-0-511-27907-2 |editionoclc=3rd166506595 |locationaccess-date=CambridgeFebruary [England]|oclc=16650659522, 2024}}</ref>

Tonic changes (EDL) are based on the phasic parameters. The spontaneous fluctuations of nonspecific EDR can be used to evaluate tonic EDA. More specifically by using the frequency of “nonspecific"nonspecific EDR”EDR" as an index of EDA during a specific time period, e. g. 30–60 seconds. Tonic EDA is considered useful in investigations of general arousal and alertness.<ref name="Boucsein 2012"/>

EDA is a common measure of autonomic nervous system activity, with a long history of being used in psychological research.<ref>{{cite book |last=Mendes |first=Wendy Berry |author-link=Wendy Berry Mendes |editor1-last=Harmon-Jones |editor1-first=E. |editor1-link=Eddie Harmon-Jones |editor2-last=Beer |editor2-first=J. |title=Methods in Social Neuroscience |chapter=Assessing Autonomic Nervous System Activity |chapter-url=http://wendyberrymendes.com/cms/uploads/Mendes%20-%20Autonomic%20nervous%20sys.pdf |date=2009 |location=New York |publisher=[[Guilford Press]] |isbn=978-1-606-23040-4 |access-date=October 20, 2015}}</ref> Hugo D. Critchley, Chair of Psychiatry at the [[Brighton and Sussex Medical School]] states, "EDA is a sensitive [[psychophysiological]] index of changes in autonomic sympathetic arousal that are integrated with emotional and cognitive states."<ref>{{cite journal|last1=Critchley|first1=Hugo D.|title=Book Review: Electrodermal Responses: What Happens in the Brain|journal=Neuroscientist|date=April 2002|volume=8|issue=2|pages=132–142|doi=10.1177/107385840200800209|url=http://nro.sagepub.com/content/8/2/132.abstract|access-date=27 April 2015|pmid=11954558|s2cid=146232135}}</ref> Many [[biofeedback]] therapy devices utilize EDA as an indicator of the user's stress response with the goal of helping the user to control anxiety.<ref>{{cite web |last=Alterman |first=Ben |title=Services Provided |url=http://www.neurobehavioralservices.com/services.php?id=8 |access-date=28 August 2015}}</ref> EDA is used to assess an individual's neurological status without using traditional, but uncomfortable and expensive, EEG-based monitoring.<ref>{{Cite book|last1=Birjandtalab|first1=J.|last2=Cogan|first2=D.|last3=Pouyan|first3=M. B.|last4=Nourani|first4=M.|datetitle=2016-10-01 IEEE International Workshop on Signal Processing Systems (SiPS) |titlechapter=A Non-EEG Biosignals Dataset for Assessment and Visualization of Neurological Status |journaldate=2016 IEEE International Workshop on Signal Processing Systems (SiPS)-10-01|pages=110–114|doi=10.1109/SiPS.2016.27|isbn=978-1-5090-3361-4|s2cid=31596383}}</ref>

EDA has also been studied as a method of pain assessment in premature born infants.<ref>{{Cite journal|last1=Munsters|first1=Josanne|last2=Wallström|first2=Linda|last3=Ågren|first3=Johan|last4=Norsted|first4=Torgny|last5=Sindelar|first5=Richard|date=January 2012|title=Skin conductance measurements as pain assessment in newborn infants born at 22–27weeks gestational age at different postnatal age|url=https://linkinghub.elsevier.com/retrieve/pii/S0378378211002131|journal=Early Human Development|language=en|volume=88|issue=1|pages=21–26|doi=10.1016/j.earlhumdev.2011.06.010|pmid=21764228|doi-access=free}}</ref>

OftentimesOften, EDA monitoring is combined with the recording of heart rate, respiratory rate, and blood pressure, because they are all autonomically dependent variables. EDA measurement is one component of modern polygraph devices, which are often used as lie detectors.<ref name="multiple" />

External factors such as temperature and humidity affect EDA measurements, which can lead to inconsistent results. Internal factors such as medications and hydration can also change EDA measurements, demonstrating inconsistency with the same stimulus level. Also, the classic understanding has treated EDA as if it represented one homogeneous change in arousal across the body, but in fact different locations of its measurement can lead to different responses; for example, the responses on the left and right wrists are driven by different regions of the brain, providing multiple sources of arousal; thus, the EDA measured in different places on the body varies not only with different sweat gland density but also with different underlying sources of arousal.<ref>{{Cite journal|title = Multiple Arousal Theory|journal = Emotion Review |date = 2016|first1 = Rosalind|last1 = Picard|first2=Szymon|last2=Fedor|first3=Yadid|last3=Ayzenberg|volume = 8|issue = 1|pages = 62–75|doi = 10.1177/1754073914565517 |s2cid = 10550306 |url = https://zenodo.org/record/898187 }}</ref>

* {{cite journal | author = Conesa J | year = 1995 | title = Electrodermal palmar asymmetry and nostril dominance | journal = Perceptual and Motor Skills | volume = 80 | issue = 1| pages = 211–216 | doi=10.2466/pms.1995.80.1.211| pmid = 7624194 | s2cid = 31812398 }}

* Carlson, Neil (2013). Physiology of Behavior. New Jersey: Pearson Education, Inc. {{ISBN|978-0-205-23939-9}}.

* Figner, B., & Murphy, R. O. (2010). Using skin conductance in judgment and decision making research. A Handbook of Process Tracing Methods for Decision Research: A Critical Review and User's Guide, 163-84163–84.

* [http://www.biopac.com/l09-eda-polygraph Pflanzer, Richard. "Galvanic Skin Response and the Polygraph". BIOPAC Systems, Inc. Retrieved 5 May 2013].

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| last2last1 = GoldsteinLoggia | first2first1 = LM. HL.

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| journal = Epilepsy & Behavior Pain

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