No matter how great your poker face might be, your skin can’t keep a secret. A window into the human mind through physiology exists beyond crystal balls, witches, or horrific psychological control. The very electricity that we associate with changing brain activity in horror movies can serve as a hidden gateway into your mind.
Electrodermal activity (EDA) recordings, particularly from the palms of the hand and soles of the feet, have been used as an evaluative tool in psychophysiological research since the late 19th century (Boucsein et al. 2012). Today, EDA is a non-invasive, and low-cost window into emotional and sympathetic arousal, contributing to research on stress, anxiety, and neurological conditions like epilepsy (Banganho et al., 2022; Posada-Quintero and Chon 2020; Rahma et al., 2022).
Underlying these applications is a physiological link between the sympathetic nervous system (SNS) and the integumentary system, through the skin (Greco et al. 2016). EDA is controlled by the SNS, or fight-or-flight response, which exhibits bodily responses, like stress, upon detection of a threat-like stimulus. Eccrine sweat glands are supplied by nonmyelinated class C fibers, regulated by the hypothalamus, alongside components of the limbic and reticular systems. Although thermoregulatory sweating occurs throughout the body, the glands on the palms and soles are particularly sensitive to emotional arousal. This perspiration is leveraged to determine psychological arousal through EDA, being tied to the amygdala through limbic system as a result of emotional excitation (Banganho et al. 2022; Greco et al. 2016).
The physical mechanism of EDA lies in the structure of the skin and its likeness to an electrical network of resistors and capacitors. The skin’s resistance varies according to ionic concentration in components like blood, sweat, and interstitial fluid, while membranes behave as capacitors by storing electric potential through ion-selective permeability. Sweat ducts contain ionic fluid, and upon sympathetic activation, increased eccrine sweat gland activity leads to changes in the skin’s electrical conductance. Conductance is inversely proportional to resistance, meaning that a decrease in resistance through sweating causes an increase in skin conductance. These changes can be seen as an EDA signal, where the stimulus inducing the change in conductance is also causing the emotional arousal (Figure 1) (Banganho et al. 2022; Greco et al. 2016).
EDA ultimately provides an advantageous means of understanding human psychophysiology through the nervous system. While its longstanding role in research as a measure of physiological arousal has proven useful, it lacks the ability to distinguish between emotions and mental states. Further innovation and improvement in this area of diagnostics may yield results specifying emotional states and expand the breadth of its application in psychological and neurological assessments.
References
Banganho, Antonio, Marcelino Santos, and Hugo Placido da Silva. 2022. “Electrodermal Activity: Fundamental Principles, Measurement, and Application.” IEEE Potentials 41 (5): 35–43. https://doi.org/10.1109/mpot.2020.2983381.
Boucsein, Wolfram, Don C. Fowles, Sverre Grimnes, et al. 2012. “Publication Recommendations for Electrodermal Measurements.” Psychophysiology 49 (8): 1017–34. https://doi.org/10.1111/j.1469-8986.2012.01384.
Greco, Alberto, Gaetano Valenza, and Enzo Pasquale Scilingo. 2016a. Advances in Electrodermal Activity Processing With Applications for Mental Health. Springer International Publishing.
Posada-Quintero, Hugo F., and Ki H. Chon. 2020. “Innovations in Electrodermal Activity Data Collection and Signal Processing: A Systematic Review.” Sensors 20 (2): 479. https://doi.org/10.3390/s20020479.
Rahma, Osmalina Nur, Alfian Pramudita Putra, Akif Rahmatillah, et al. 2022. “Electrodermal Activity for Measuring Cognitive and Emotional Stress Level.” Journal of Medical Signals and Sensors 12 (2): 155–62. https://doi.org/10.4103/jmss.JMSS_78_20.
Winter, Michael, Rüdiger Pryss, Thomas Probst, and Manfred Reichert. 2020. “Towards the Applicability of Measuring the Electrodermal Activity in the Context of Process Model Comprehension: Feasibility Study.” Sensors 20 (16): 4561. https://doi.org/10.3390/s20164561.
Comments
21 Responses to “Can electricity read your mind?: Electrodermal Activity”
Hey iSci!
EDA is something I remember reading about as a diagnostic tool in a psych class a few years ago. I never truly understood how it could be used to study psychological conditions or how its mechanisms worked. Once I looked deeper, I found the underlying physics super interesting, which inspired me to write this post combining psychology, physics, and a bit of neurology! I hope you enjoy reading my post, and please let me know if you have any editing suggestions, especially any suggestions that might help me cut down on my word count :).
Ann
Hi Ann,
Nicely done with your blog! I think this topic is so cool, and it was awesome to read more about how EDA can be used. Below are some suggestions to help improve your blog:
P2S2/3: I think these two sentences can be combined, to reduce redundancy. Perhaps something like: “Today, EDA provides a lower cost, non-invasive window into emotional and sympathetic arousal, aiding research on stress, anxiety, and neurological conditions like epilepsy (Banganho et al., 2022; Rahma et al., 2022).”.
P3S3: pluralise system, “… limbic and reticular systems”.
P4S4: I would reword this, for clarity/flow, maybe: “Conductance is inversely proportional to resistance, meaning that a decrease in resistance through sweating causes an increase in skin conductance.”
Figure 1 S2: instead of “skin’s response as raw skin conductance is measured” I would say “skin’s response is measured as raw skin conductance”.
Overall, super well written!
Happy editing,
Aven 🙂
Hey Aven,
Thank you so much for the editing suggestions, all have been incorporated. They’ve definitely helped improve the readability of my writing.
Ann
Hi Ann,
This was such an interesting topic and I really enjoyed reading it! Your introduction was absolutely amazing and immediately captured my interest! Here are a few suggestions:
Paragraph 1, sentence 1: this sentence seems a little bit long. Perhaps you can separate it into two or remove some clauses.
Paragraph 2, sentence 2: similar comment here. I think you could remove either “stress” or “particular” to make the sentence a bit more concise.
I love how you define cholinergic and adrenergic fibers! That was very helpful for readers.
Paragraph 4: Perhaps you can say the word “equals” instead of writing the equation in the text.
Figure caption: if you are citing multiple sources to explain the image, it might be good to add the in-text citation where you found this image into the first sentence of the caption.
Happy editing,
Ria
Hi Ria,
Thank you so much for taking the time to read my blog post, as well as the kind words and suggestions :). All of the edit suggestions have been incorporated.
Thank you again!
Ann
Awesome work with your draft Ann, I really enjoyed the topic and thought it was certainly an engaging one! I just have a couple of recommendations that you can choose to use, word-permitting!
– In P1S3, I would recommend adding a comma after the word “movies” for better readability
– (P2S1) I would also recommend defining “palmar and plantar skin” for those who may not have background research on the topic, as context.
– I would also recommend splitting up P4S2 into two different sentences for better flow.
Happy editing!
Sayana 🙂
Hi Sayana,
Thank you for reading through my draft and providing these editing suggestions! I’ve taken all of them into account, and they’ve definitely improved the quality of my writing.
Thanks again :).
Ann
Hi Ann,
This was a really interesting and well-written blog post! I enjoyed how you made connections between multiple different disciplines. A few suggestions for your final draft:
– Consider connecting your first two paragraphs, or including your initial mention of EDA recordings in your introduction, as it doesn’t currently have a ‘connection’ to the rest of your piece.
– Consider rephrasing P3S2 for clarity by removing commas – this could look like “[…], which activates stress-induced bodily responses upon detection of a threat-like stimulus.”
– In your conclusion, consider expanding on what types of applications we might see if the future (if you have the word count)! This is a really interesting point and I’d love to see more.
Overall fantastic work! I’m really looking forward to reading your final post.
Happy editing!
Charlie
Hey Charlie,
Thank you for all of the editing suggestions, I have taken all into account except the last because I’m super tight on word count.
Thank you again!
Ann
Hi Ann,
Great post! The resistor-capacitor comparison made the physics click for me.
Two things:
In P3S4, you say cholinergic fibers handle thermoregulation and adrenergic fibers handle emotional arousal. Since EDA is measured on the palms, it might help to say a line about how researchers separate the two, or if both are at play in a reading.
Your conclusion says EDA can’t distinguish between emotions, but your figure already splits the signal into tonic and phasic parts. Tying those together would make the limitation land harder.
Happy editing!
Gurdit
Hey Gurdit,
Thanks for taking the time to read my post. In terms of elaboration, I unfortunately don’t think I can look too much into the specifics because of my already high word count, but I’ll look to add some more details into the figure caption.
Thank you again!!
Ann
Hey Ann,
This was a very interesting blog post, and has given me a good insight into this technique I had never heard of before. I have a few suggestions below that you may find useful when editing.
– P2: If you reword this to “Electrodermal activity (EDA) recordings, particularly of palmar and plantar skin, have been an evaluative research tool to record psychophysiological responses since the late 19th century (citation). Today, this is a non-invasive and low-cost diagnostic tool used in research on stress, anxiety, and neurological conditions like epilepsy, to study emotional and sympathetic responses (upon cognitive/emotional stimulation) (citation).” you may be able to reduce the word count of your intro.
– P3: Consider including a figure here to show the link between the SNS and integumentary system.
– Fig 1: If you are able to spare some words, could you elaborate on tonic vs phasic conductance and the stimuli involved in the caption or in P4? This would make the graph a little more connected to the intro, since you mention stress, anxiety and epilepsy there.
Overall, good blog post, and I look forward to reading your final version!
– Vihaan
Hey Vihaan,
Thank you for all of your suggestions.
The paragraph 2 concerns have been fixed with some earlier suggestions! I originally had a figure for the SNS pathway and its connection to the integumentary system but decided to stick to the single figure to keep the focus more bio-physical and keep within word count. I love your idea about connecting Figure 1 to the intro so I’ll definitely work on that.
Thanks again.
Ann
Hi Ann,
Great job on this blog post! It was really informative and a wonderful read. Please see below for a couple of suggestions, if you agree:
– the first sentence of your P2 is a bit ling and run-on. Consider rewording, such as: “Electrodermal activity (EDA) recordings, particularly of palmar and plantar skin, are one of the original methods of recording psychophysiological responses. Examples of psychophysiological responses include stress and ___ and these responses have been used ….”
– your P3 is very informative but consider explaining some of the jargon you use, such as class C fibres and integumentary. Though these are briefly explained, it might be more accessible to explain them more explicitly.
Great job overall, happy editing!
Janaya:)
Hi Janaya,
Thanks for the suggestions, and for taking the time to read my post!! The P2 sentence has ben fixed and the changes in P3 have also been noted and added.
Thank you!! :).
Ann
Hi Ann,
Great post. I thought that your poker face opener was a strong hook, and you did well to transition the post from the nervous system to the electrical properties of skin.
Some comments/suggestions:
– Worth double-checking the cholinergic/adrenergic distinction. Eccrine glands are mainly cholinergic for both thermal and emotional sweating; emotional sweating differs mostly in its central control (limbic vs. hypothalamic).
– Some explanations are circular: “the stimulus inducing the change in conductance is also causing the emotional arousal.” Stating the chain directly (stimulus, arousal, sweating, higher conductance) would be clearer.
– The tonic/phasic distinction (SCL vs. SCR) only appears in the Figure 1 caption. Moving it into the body and trimming the caption could help.
– Smaller fixes: “reticular system” should be “systems,” and Posada-Quintero (2020) is never cited in text.
Once again, solid post.
Best of luck with the edits,
Luca
Hey Luca,
Thanks for taking the time to read my post, and for the suggestions! Your catch was spot on so I honestly just omitted the cholinergic/adrenergic as a whole, as it didn’t add much to the section, and I simplified it. Every other suggestion was also incorporated.
Thanks again!
Ann :).
Hi Ann,
This was a really interesting and informative blog post! Super cool topic. A couple suggestions to keep in mind while editing:
– P2S1 is a little long and the meaning gets a little lost as a result. Consider breaking it up, for example: “Electrodermal activity (EDA) recordings, particularly of palmar and plantar skin, are one of the original methods of recording psychophysiological responses, like stress. EDA has been used as an evaluative tool in psychophysiological research since the late 19th century (Boucsein et al. 2012).”
– I think P4S1 could be compressed for a little better clarity: “The physical mechanism of EDA lies in the similarity between the structure of the skin and an electrical network of resistors and capacitors.”
– Consider mentioning EDA in your first paragraph to make it feel a little more cohesive.
– Consider expanding on some of the possible applications of EDA if you have the word count.
Happy editing!
Maegan
Hey Maegan,
Thank you for all your suggestions! I’ll look to take them all into account and cut down on a bit of writing at the same time so that I can expand on everything that you suggested.
Thank you!
Ann
Hello Ann 🙂
I liked how you connected the nervous system with the electrical properties of our skin. It’s cool how something as simple as sweating can provide information about physiological responses to stress and emotions!
I just have a couple of suggestions:
In your fourth paragraph, you explain how changes in sweating affect skin conductance. Maybe you could briefly mention how other factors, including physical activity or environmental temperature, might influence EDA measurements.
In your conclusion, you mention that EDA cannot distinguish between different emotional states. I think adding a brief example of how two different emotions could produce similar EDA responses would help readers understand this limitation.
I know the word count is tight, so these are just a couple ideas! Overall, great job! Looking forward to reading your final!
Hi Hana,
Thank you for reading through my post and for the suggestions! These are all great ideas but I think i might be limited due to word count, so I’ll look to condense and cut stuff down first, and reapproach these suggestions once that is done!
thank you!
Ann