Novel expert system to study human stress based on thermographic images

Abstract

Human stress is a physical or emotional feeling. It can come from any situation or thought that makes one feel frustrated or nervous. Different biological manifestations take place in the presence of stress, such as tension, headache, and insomnia. Recent studies have reported that human stress can be related to facial expressions and fingertips due to temperature changes in the skin. Infrared thermography is a non-invasive technology that allows for the monitoring and analysis of human skin temperature. However, many works reported in the literature perform a manual analysis, depending on expert personnel, resulting in considerable human and economic efforts. In addition, the analyses reported to date with thermography are only based on the study of body parts. To reduce the limitations of these methodologies, expert systems have been proposed that simulate the thought process of a human expert to solve decision problems, which may be helpful for people focused on the health and psychology area who do not have expertise in the study of stress. Therefore, this paper proposes a novel expert system based on infrared thermography and thermal analysis of facial skin and fingertips, a rule-based method, and heuristic knowledge to classify and diagnose human stress in undergraduate university students. The system had the support of experts in the study of human stress and was validated in a stress study. The novel expert system was implemented in a local database that consisted of a group of 100 participants, undergraduate university students, of which 70 were stimulated by the Trier Social Stress Test (TSST) protocol and 30 were not induced to human stress, obtaining an accuracy in the expert system stress classification of 91.0%.