Evaluation of stress reactivity and recovery using biosignals and fuzzy theory

This paper is about the evaluation of stress reactivity and recovery using biosignals and fuzzy theory. We induced mental stress by means of a coin-stacking task. During the experiment, 4 kinds of biosignals, which are frontalis EMG, ECG, peripheral skin temperature and skin conductance level, were acquired. Then, the degree of stress was assessed by synthetically analyzing those signals using fuzzy inference. From the fuzzy inference result, the parameters (Amount of Physiological Change/Amount of Imposed Stress) and (Time to 25% Recovery), which represent reactivity and recovery respectively, were derived. We made a graph using the reactivity parameter as an abscissa and the recovery parameter as an ordinate for each subject. From the graph, the distance from the origin to the coordinate ((Amount of Physiological Change/Amount of Imposed Stress), (Time to 25% Recovery)) was introduced as a stress index. An insensitive reactivity and a fast recovery is an effective coping with stress. Therefore, the small value of the stress index proposed in this research will indicate being in good health.