We all have that inner voice designed to help us stay alive, avoid discomfort and survive as creatures on Earth.

These participants attempted ... more difficult if you did not have an inner voice because you have to repeat the words to yourself inside your head in order to remember them," says linguist ...

There's a cultural stigma, especially in the US, that hearing voices in your head is inherently a sign ... They intentionally create these voices. They're called Tulpamancers.