Our body is an interconnected place. Very few physiological events occur in isolation – when our heart rate increases, our pupils dilate, our muscles tense, and signals are sent to and from the brain to regulate (and be regulated by) much of this. The coordination of multiple parts of our body acting together ensures that we (usually) react properly to our environment.

In a similar way, our skin generates signals that can be the result of other events in our body. This is what the galvanic skin response (GSR, but sometimes also referred to as EDA or electrodermal activity) centers on. The signals are the result of our skin conducting electrical currents due to changes in sweat gland activity.

These changes in sweat gland activity are connected to another source of activity – changes in our emotional states. These emotional states have their origins in the brain as the initial trigger for these downstream events.

There is a wide range of research showing an association between an individual’s emotional state and changes in GSR activity [1, 2, 3]. Additionally, meta-analyses (studies that collect the results from multiple studies) point to a largely generalized GSR response to emotional arousal [4].

Below, we’ll go through some of the articles that show an association between GSR activity and emotions, and how these findings can be used to better understand and research emotional states. While there is continued debate about the number (or even existence) of discrete emotional states [5], for the sake of simplicity we’ll focus below on the six core emotions originally proposed by Ekman [6].

ekmans basic emotions

Fear

Eliciting fear in the laboratory can be a darkly comic task – contraptions involving tilting chairs, and other scare tactics have previously been used (although differentiating this effect from feelings of surprise is difficult [4]).

In one somewhat ethically-questionable experiment, participants were provided with a false but threatening medical diagnosis while their GSR, heart rate, and respiration levels were recorded. They found that this fear-eliciting scenario increased the general levels of GSR activity [7].

Another experiment deceived participants by informing them that the reason for the study was to test their blood pressure, and simply to relax. The events that followed, all staged, involved a small electric shock being delivered to the participant and the experimenter “then exclaimed with alarm that this was a dangerous high-voltage short circuit” [8]. As the article also states: “The experimenter created an atmosphere of alarm and confusion”. Surely enough to elicit fear.

The participant was of course then fully informed about the scenario and ultimately debriefed. The results showed an increase in GSR activity in response to the fearful situation. Both results showed that feelings of fear are associated with a rise in GSR activity, providing a validation of this emotional state.

Anger

Research also shows that an increase of GSR activity is linked to feelings of anger, as compared to a neutral state.

A study at the University of Marburg used an experimental context in which a frustrating set of questions, an annoyed sounding researcher, and a faulty intercom (among other staged but angering components) were used to elicit feelings of anger. At the same time, measures of GSR activity, heart rate, and fEMG (facial electromyography) were recorded.

They found that the GSR levels were significantly increased for participants, when compared to participants in a fear-eliciting condition.

Using a slightly less stressful experimental setup, Marci and other researchers used brain imaging and GSR while participants were asked to recall memories associated with anger [9]. They found that GSR levels were significantly increased when compared to the neutral condition.

Disgust

Measuring disgust requires a strong stomach. As Kreibig and others point out, there are two primary ways in which disgust is triggered with participants, either through subjects related to pollution or contamination with “pictures of dirty toilets, cockroaches, maggots on food, foul smells, facial expressions of expelling food” or in relation to bodily harm with visual scenes of “injections, mutilation scenes, bloody injuries” [4].

In a slightly more comfortable context, a study by Collet and others used the presentation of images of facial expressions exhibiting specific emotions as the stimuli. The participants were instructed to try and feel the emotion that was being displayed. Using a range of autonomic nervous system measures, including GSR, skin temperature, and respiration, the researchers found a specific increase in GSR activity for the disgust related conditions [10].

Another study by Williams and others used both GSR and fMRI (functional magnetic resonance imaging) to investigate different emotional responses, also finding an increase in GSR activity within the disgust condition, compared to controls [11].

hands gsr

Happiness

Stéphanie Khalfa and other researchers [12] conducted a study in which happy and sad music was presented to participants while a range of measurements were collected, including GSR, heart rate, and fEMG. They found a significant increase of GSR activity in terms of SCR (skin conductance response) in the happy music condition, as compared to the sad music condition.

In a study by Levenson and others [13], a range of multimodal data was collected in order to determine if mimicking emotional facial expressions could direct physiological activity. The researchers used combined measures of heart rate, galvanic skin response, temperature, and muscle activity. They found a significant association between displaying a happy facial expression and increased galvanic skin response levels, as well as a correlated self-report of the emotion, suggesting a link between the experience of happiness and galvanic skin response intensity.

Other studies have also related feeling of happiness with increased GSR responses, often using a multimodal approach to bolster the claims [3, 14]. Research clearly shows a link between increased GSR activity levels and feelings of happiness.

Surprise

While each of the other basic emotions fall along the emotional continuum as positive (happiness) or negative (anger, disgust, fear, sadness), surprise is an emotion with neutral valence [4]. Despite this, increases in GSR activity are more often associated with this emotion [10]. More research however remains to be done to provide definitive conclusions about this emotion and its relation to GSR activity levels.

Sadness

The evidence for levels of GSR activity associated with feelings of sadness is relatively more mixed than the other aforementioned emotions. This is in part due to the apparent differences in sadness associated with crying, and sadness that is not associated with crying – the former is often linked to increased GSR activity [15], while the latter is linked to decreased GSR activity [16].

One study used a film clip taken from “The Champ”, a film widely used to elicit feelings of sadness (not an Oscar nomination, but certainly an accolade for a film). They found a reduction in GSR activity for the control participants (and no change for the other participants who had disruptive behavior disorders [17]). Other research has used a similar approach and reported similar findings, but with the film Bambi [18].

bambi fear movie

Conclusion

The above research clearly shows a trend towards increases in GSR activity being related to emotional intensity (the more an individual experiences an emotion, the more likely that a detectable change in GSR activity is seen). However, there are some exceptions – decreases in GSR activity are reliably found when the individual experiences relief [19], contentment [2] and sadness (when the person isn’t crying [16]).

Various studies have attempted to elucidate identifiable differences in physiological responses to specific emotional states – that multiple measures could point towards a clear indication of a certain emotion (e.g. [10]). This is a widely debated topic, and no absolute consensus yet exists [4], yet one aspect does appear clear – as participants experience emotions (with a couple of exceptions), their GSR activity is more likely to increase. The multimodal approach does however seem to offer the best hope of success in finding the Holy Grail of emotion research – knowing how someone is feeling without having to ask them.

I hope you’ve enjoyed reading about how different emotional states are related to GSR activity. If you’d like to learn more about how GSR measurements can provide an understanding of human behavior and emotions, download our free guide below.

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References

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[2] Hess, U., Kappas, A., McHugo, G.J., Lanzetta, J.T., Kleck, R.E. (1992). The facilitative effect of facial expression on the self-generation of emotion. International Journal of Psychophysiology 12, 251–265.

[3] Tsai, J.L., Levenson, R.W., Carstensen, L.L. (2000). Autonomic, subjective and expressive responses to emotional films in older and younger Chinese Americans and European Americans. Cultural Diversity and Ethnic Minority Psychology 15, 684–693.

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[17] Marsh, P., Beauchaine, T.P., Williams, B., 2008. Dissociation of sad facial expressions and autonomic nervous system responding in boys with disruptive behavior disorders. Psychophysiology 45, 100–110

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[19] Blechert, J., Lajtman, M., Michael, T., Margraf, J., Wilhelm, F.H., 2006. Identifying anxiety states using broad sampling and advanced processing of peripheral physiological information. Biomedical Sciences Instrumentation 42, 136–141.