Facial Thermal and Blood Perfusion Patterns of Human Emotions: Proof-of-Concept
This is a proof-of-concept study that could improve emotion recognition systems, but it is incremental as it builds on existing thermographic methods by introducing blood perfusion analysis.
The study investigated whether facial thermal and blood perfusion patterns can differentiate positive and negative emotions, finding that blood perfusion images provided greater contrast and more consistent vasomotor responses than thermographic images, suggesting they are a better biomarker for emotion identification.
In this work, a preliminary study of proof-of-concept was conducted to evaluate the performance of the thermographic and blood perfusion data when emotions of positive and negative valence are applied, where the blood perfusion data are obtained from the thermographic data. The images were obtained for baseline, positive, and negative valence according to the protocol of the Geneva Affective Picture Database. Absolute and percentage differences of average values of the data between the valences and the baseline were calculated for different regions of interest (forehead, periorbital eyes, cheeks, nose and upper lips). For negative valence, a decrease in temperature and blood perfusion was observed in the regions of interest, and the effect was greater on the left side than on the right side. In positive valence, the temperature and blood perfusion increased in some cases, showing a complex pattern. The temperature and perfusion of the nose was reduced for both valences, which is indicative of the arousal dimension. The blood perfusion images were found to be greater contrast; the percentage differences in the blood perfusion images are greater than those obtained in thermographic images. Moreover, the blood perfusion images, and vasomotor answer are consistent, therefore, they can be a better biomarker than thermographic analysis in identifying emotions.