Stress measurement from tongue color imaging

A growing number of studies show links between changes in tongue appearance and human health conditions. This paper studies tongue color changes in the context of stress to explore the feasibility of providing a novel and non-invasive stress measurement method. In a laboratory study, 24 participants were asked to perform a calm and a stressful math task and to take a photo of their tongue right after each of the tasks. We observed subtle but consistent color differences between calm and stress tasks for up to 75% of the participants, which was consistent with both self-report and physiological metrics of stress. Moreover, we observed significant correlations of up to 0.72 between certain tongue colors and long-term stress assessed with the 10-item Perceived Stress Scale questionnaire. We discuss the potential implications of this work and highlight some lines of future research.