According to a study by the University of Granada in Spain, you really CAN catch someone telling a lie by checking their nose.    They call it "the Pinocchio Effect", but a person's nose doesn't get bigger, it gets WARMER.

Scientists looked at thermal images of people's faces, and found that different areas of their face changed temperature when they were doing different tasks.

If someone was working on a difficult mental task, the temperature around their nose and the muscles in the corners of their eyes dropped, and if someone was feeling anxiety, the area heated up.    And when someone was LYING, the temperature around their nose also jumped.

(Livescience.com)