Effect of Mental Workload Related Stress on Physiological Signals

Mental workload related stress can be defined as body's response to an increased cognitive load. As natural response of the body, stress itself is not a harmful thing, as a matter of fact it is sign of healthy body. However, remaining in stress for a prolonged duration or experiencing stress many times a day is harmful for health. Thus, measuring stress has been a topic of interest for last couple of decades, and changes in physiological signals caused by stress have been studied. In this study, we studied the changes in four physiological signals caused by (MWL) mental workload related stress of 26 participants. The four physiological signals studied were electrodermal activity (EDA), Breathing rate (BR), Skin temperature (ST) and blood pressure (BP). Stress was induced in subjects by different methods previously used in literature as `public speaking', `smelling different odors' and `playing stressful games'. Results indicated that EDA changes rapidly with changing stress levels, whereas public speaking changed the value of EDA the most, with an average change of up to 8 micro siemens. Skin temperature also increased with increasing stress, with about 0.8 degree centigrade on average. Once the skin temperature rose, it did not come down with decreasing stress level, instead it took some time to cool down. BP and BR did not follow a pattern that can be indicative of a consistence trend in their change due to changing stress.