Differential effects of physical and psychological stressors on electrodermal activity

Stress being labelled by WHO as "the health epidemic of 21^st century" need to be treated as a clarion call for devising strategies that aim at its early detection, for the reason that stress is the cause as well as the catalyst for several chronic human health disorders. The work reported here in is a progression towards the development of a stress detection system based on the electrodermal activity (EDA) in humans, which can further be incorporated into a wearable vital signs monitor. The utility of EDA as a potential physiological measure for classifying physical and psychological stressors is analyzed in this paper. A group of 12 subjects (8 males and 4 females, age: 25.4 ± 3.1 years, mean ± SD) volunteered to participate in a laboratory stress task that included a psychological stressor close to real life work stress scenario and a physical stressor. The capability of stressors to elicit persistent stress response was validated by assessing variations in salivary cortisol levels. EDA was monitored throughout the experiment sessions as a measure of sympathetic activation in subjects. Six classification models were investigated concerning their usability to distinguish physical and psychological stressors based on EDA. A maximum accuracy of 95.1% was achieved using linear discriminat analysis (LDA) based classifier which imply that EDA is indeed a potential discriminate measure to classify physical and psychological stress responses. Furthermore, the best feature combination for maximum classification accuracy was also determined.