Yes, Pinocchio was on to something. No, your nose doesn't grow when you lie. However, it gets hotter, and you can measure that to tell whether or not someone is telling the truth. The phenomenon, discovered by Spanish scientists, is aptly named the Pinocchio Effect.
So what's behind this? When you lie, there's an increase in anxiety. That rise in anxiety makes the tip of the nose hotter. It's possible, with great mental effort, to cool it down.
These researchers have been doing a lot of work on thermal imaging. They claim that it can detect sexual desire and arousal in men and women, and they have found that women and men are aroused at the same time, although women subjectively indicate that they're not. They also claim that each style of dance has a specific thermal imaging.
Learn more about their fascinating research here.