Development of a skin temperature measuring system for non-contact stress evaluation

Skin temperature is an effective indicator for objectively evaluating human sensations, because it is controlled by sympathetic nerve activity which reflects the course of information processing in the brain. In this paper, the authors show a method to evaluate stress from skin temperature and an equipment which continuously measures skin temperature of an subject working in front of a computer terminal. An experiment is performed to investigate a relationship between stressful task and the skin temperature. The experiment shows that there is a high correlation among stress, skin temperatures on nose and forehead. From this experiment, a regression equation is derived which computes the intensity of stress from skin temperatures on nose and forehead. A non-contact skin temperature measuring system is developed based on knowledge obtained in the experiment. The system comprised of an infrared camera, color camera, image processing unit and workstation. The features are the abilities to track nose and forehead positions of an subject doing computer operation automatically and to evaluate the stress continuously.