Under the skin: Exploring 2-month-olds' thermal reactions in different social interactions with mother and stranger.

Physiological adaptations to external stressors can reveal socio-cognitive health in infancy. With the use of thermal imaging and behavioural analyses, the current study examined the arousal markers accompanying infants' interactions with a familiar and an unfamiliar person. To address the current research question, the mother and a complete stranger interacted with 2 to 3 month-old infants (N= 10, 2 boys)in three different conditions: Neutral, Play, and Compliment. Behavioral analyses showed that overall gaze was longer to the Stranger compared to the Mother independent of condition. Physiological findings showed that skin temperature was significantly higher with the stranger independent of condition. The regions of the face that passed the significance threshold included the maxillary area, the nose, and the forehead. Both behavioral and physiological findings emphasize the ability of the infant to distinguish between a familiar and an unfamiliar person. Most importantly, however thermal imaging has proven to be a promising tool in physiologically differentiating between variable social conditions in very young infants opening up a new experimental portal for identifying healthy physiological development.