Answer:
Acording to the video "Guide to GSR Biofeedback Techniques for the Natural ADHD Practitioner by Jason Alster , a GSR signal is labile in ADHD students and shows stress when an ADHD student is trying to sit still for a few minutes in a eyes open and an eyes closed condition. The GSR can be a measure of relaxed concentration in ADHD and test anxiety. Also , the GSR is taken from the skin and the skin is an organ that covers the whole body so it represents stress effects on the whole body. The advantage is that as a biofeedback signal it is easy to learn to control stress from it as a psycho physiological parameter