Galvanic Skin Response Studies Reveal Distinct Correlation Patterns


While we often think about galvanic skin response, or electrodermal activity, as being principally associated with lie detector tests, the authors of a chapter in the Handbook of Psychophysiology point out that “measures have been applied to a wide variety of questions—ranging from basic research examining attention, information processing, and emotion to more applied clinical research examining predictors and/or correlates of normal and abnormal behavior.”1


Although this chapter focuses almost exclusively on a variety of experiments that look at GSR in the context of physical responses to psychological states, a few studies are reviewed and discussed that are important to understanding ZYTO biocommunication technology and services.


Sweat glands and galvanic skin response


The authors point out that the skin is the largest organ of the body and accomplishes a wide range of dynamic functions. As a result, the skin is constantly receiving signals from the brain and the rest of the body, which is one of the reasons why the skin can function as a helpful indicator of various states of the body.


It’s important to note that there are two different types of sweat glands on the skin: eccrine and apocrine glands. Apocrine glands, which are relatively unstudied, are focused around hair follicles, and are primarily located in the armpits and genital areas. Furthermore, very little is currently known about the GSR responsiveness of these glands. The eccrine glands, on the other hand, cover most of the body, are most dense on the palms of your hands and the soles of your feet, and have been well studied and documented in various studies of GSR.


While the primary goal of the eccrine sweat glands is of course thermoregulation, the eccrine glands on the hand and feet have been theorized to function mainly as an aid for grasping. At the same time, studies have suggested that eccrine glands in general may respond more to emotional stimuli than to thermal stimuli, which certainly makes sense if you consider the often-unfortunate role that sweating (particularly on the hands and feet) plays when we experience certain intense feelings, such as nervousness or fear.


Changes don’t occur in isolation


Another important set of studies that the authors review reveals the importance of realizing that GSR responses reflect changes in electrodermal activity that “do not occur in isolation” and must be understood “as part of a complex of responses mediated by the autonomic nervous system.” This is one of the many reasons why it’s so important to not attempt to measure GSR in isolation, but instead to gather a variety of responses to many stimuli in order to correlate the data and get a fuller understanding of the body’s responses. Gathering a variety of responses to gain a more complete understanding is at the heart of what ZYTO technology does.


Distinct patterns of correlation



Similarly, the article reviews a variety of studies that introduce the term “individual response stereotypy,” which refers to the way in which various test subjects “produce the same pattern of relative change across physiological systems” but that “this pattern differs across individuals.” In other words, individuals have unique, and at times counterintuitive, correlational patterns across physiological systems.


As an example, knowing the ways that body systems are linked, we may sometimes be led to assume that responses affecting one system will always affect other linked systems in the same way. Nevertheless, various GSR studies have shown that these links correlate poorly from individual to individual. In other words, Person A will have their own distinct patterns of correlation, while Person B will have totally different patterns—another reason why it is so important to have the unique, individualized information of every individual made possible by GSR technology.




1. Dawson, Michael E., Anne M. Schell, and Diane L. Filion. “The Electrodermal System.” In Handbook of Psychophysiology. (Cambridge, England: The Cambridge Press, 1990).