Thermal imaging is often used in warfare, law enforcement and satellite technology but now it has been used to check out the human face. 16-23 young women were touched with a handheld device on the face, arm, palm and chest. The temperature changes in the facial area could be detected with the thermal images obtained.
Traditional thermal coloration while interacting with the opposite sex. Red indicates where the temperature increased above the baseline temperature; Credit: © Amanda Hahn
When you are aroused, face and body temperatures rise. Fear, stress and sex are the main emotional events concerned. A paper by Amanda C. Hahn and her colleagues at the University of St. Andrews reports on the techniques above and the implications.
The periorbital region (around the eye) is affected by an increase in temperature within 300ms, with a corresponding decrease in the cheeks. In infants, the whole forehead temperature decreases if they are stressed by for example the absence of the mother. In adult interpersonal contact, in the absence of any direct emotional context, Amanda and her team attempted to discover any gender bias in responses and then went on to assess the face's temperature changes with heterosexual contact.
The figure shows an example of the greyscale thermal image with delineation mapping and five ROIs displayed: (A) forehead region, (B) periorbital region, (C) nasal region, (D) mouth region, (E)cheek regions (averaged); Credit: © Biology Letters
Tactile contact was found to raise facial temperature, even when touch is accidental. The opposite sex is apparently the strongest stimulus, with the periorbital, nose and mouth regions mostly affected. What was almost alarming was the extent of the change with an average of 0.3°C and some women rising by 1°C.
What your mother never could have told you was that science still can't determine if these temperature changes are detectable. If they are, and they certainly provide useful information, then the whole of human relationships could be built on such receptivity.
Social cues, attraction, skin colouring and several other possible signals can be sent out through sight, touch or smell. Even if the individual goes undetected by others, their very own detectors could be altering their behaviour. Amanda Hahn believes that if we investigate skin colour change with temperature, we could find signals that we find unconsciously guiding us in our love lives!