Study of Emotional contagion through Thermal Imaging: A pilot study using noninvasive measures in young adults
Authors: Joshi Prachi , Banerjee Hirak , V Muli Avdhoot , Routray Aurobinda , Patniak Priyadarshi 
Published: June 2024

Emotional contagion, the process of unconsciously mirroring others’ emotions [6], occurs through various channels including facial expressions, vocal tone, and body language, influencing social interactions and responses to cultural stimuli like music and movies [3], [4], [1]. Facial expressions, analyzed using the Facial Action Coding System (FACS), provide insights into emotional transmission [2]. Thermal imaging, a technique for measuring facial temperature changes, offers a noninvasive method to study emotional responses [5]. However, the facial thermal response to emotional contagion remains understudied. This study aims to investigate how emotional contagion affects facial blood flow among highly emotionally contagious individuals, identified using noninvasive measures. Thermal imaging will capture temperature changes across ten designated facial regions of interest (ROIs), shed-ding light on facial muscle activation. By interpreting temperature variations in these ROIs, researchers seek to understand the physiological processes underlying emotional contagion. Previous studies have shown inconsistent findings regarding facial temperature changes during emotions like fear and joy, highlighting the need for further investigation. This research aims to clarify these discrepancies and advance our understanding of facial thermal responses to emotional contagion, contributing to the broader field of emotion research and potentially informing therapeutic interventions and communication strategies.Initially, Eighteen participants participated in the study. Two groups of standardized emotionally contagious video stimuli (Happy, Fear) were used to induce emotional contagion.The videos started with a one-minute relaxing clip to help participants achieve a neutral emotional state before watching the emotional contagion clips. Following the two-minute emotional contagion video, a blank screen was displayed for one minute to observe the aftereffects of the emotional contagion on participants. Facial temperature was recorded from Fluke Ti 400, and facial expressions were recorded from the webcam. Participants were asked to fill out an emotion-intensity feedback form to rate the experienced emotion and its intensity during video stimuli. Eight participants’ data was removed from further analysis because of inconsistencies. Out of the remaining ten, we further shortlisted five highly emotionally contagious participants with the help of the emotional contagion scale. Ninety baseline and arousal thermal images (10 seconds each) were identified and analyzed using FACS. Ten important regions of interest(ROIs) were selected for facial thermal variations. The interpretation of temperature patterns on selected ROIs produces a physiological time series signal, reflecting changes in blood flow associated with emotional responses. As previously discussed, blood flow radiates across the blood vessels when an emotion happens, which is why a gradual shift in the baseline occurs when an emotion takes place. To assess significant differences in facial thermal temperatures from baseline to emotional contagion, the Mann-Whitney U test and average temperature differences were used. During both emotions (fear and joy), the temperature of the nose decreased on the faces of participants. However, during fear, the temperature dropped in the forehead, left eye corner, and right cheek, while during joy, it increased in the left eye upper region. Additionally, while in fear, the left eye upper, right eye upper, and nose exhibited decreased temperatures, whereas during joy, the forehead, left and right eye corners and nose showed reduced temperatures. Mann Whitney U test showed significant emotional arousal in all the ROIs. Only the right eye corner and left cheek in two participants during fear and the right eye corner during joy in one participant was showing insignificant differences.[1] Amy Coplan. Catching characters emotions: Emotional contagion responses to narrative fiction film. Film Studies, 8(1):26–38, 2006.[2] Paul Ekman. Facial expression and emotion. American psychologist, 48(4):384,1993[3] [3]Carolina Herrando and Efthymios Constantinides. Emotional contagion: a brief overview and future directions. Frontiers in psychology, 12:2881, 2021[4]Giuliana Isabella and Hamilton C. Carvalho.Chapter 4 - emotional contagion and socialization: Reflection on virtual interaction. In Sharon Y. Tettegah and Dorothy L. Espelage, editors, Emotions, Technology, and Behaviors, Emotions and Technology, pages 63–82. Academic Press, San Diego, 2016 [5]Sophie Jarlier, Didier Grandjean, Sylvain Delplanque, Karim N’diaye, Isabelle Cayeux, Maria Ines Velazco, David Sander, Patrik Vuilleumier, and Klaus R. Scherer. Thermal analysis of facial muscles contractions. IEEE Transactions on Affective Computing, 2:2–9, 2011.Eliska Prochazkova and Mariska [6]E. Kret. Connecting minds and sharing emotions through mimicry,Neuroscience Biobehavioral Reviews2017