Proven! When you lie your nose, doesn’t get bigger, but it does get warmer! On the contrary a lot brain effort makes your nose colder, and anxiety makes the whole face warmer.
The experimental psychology unit at The University of Granada, using termography (termal image) came to this conclusion after a series of experiments with this technology.
Another cool thing they found was that the temperature in people that felt empathy also changed. For instance a person who sees someone else getting electric shots on their elbow, if they felt empathy, their own elbow would heat up too!