People scratch their heads when they want to show that they are in the process of thinking.
Another reason why people scratch their heads when they are confused is to show that feeling without having to say it out loud.
People feel that their skin is getting hot when they are shy whether because of an embarrassing thought or question. This makes them scratch their heads.
The human mind makes the thought of scratching the head work when they are under pressure or stress.
The blood rush emerges when a thought is developing in the brain, which causes the skin of the scalp to feel the rush and the itch that comes with it.
It is an automatic response when the brain is taking a while to process a thought or an answer.
Movies, cartoons and other sorts of media show that people scratch their heads when they are in thought, which is something that we develop subconsciously and begin to imitate.
It is originally a Greek myth that said that when a god wanted to be all knowing, he went to a magician to give him a potion to rub on his head when he wanted to know something.