The last great mystery of the mind: meet the people who have unusual – or non-existent – inner voices

Does your internal monologue play out on a television, in an attic, as a bickering Italian couple – or is it entirely, blissfully silent? 

Claudia, a sailor from Lichfield in her late 30s, is not Italian. She has never been to Italy. She has no Italian family or friends. And she has no idea why a belligerent Italian couple have taken over her inner voice, duking it out in Claudia’s brain while she sits back and listens.

In order to understand how the inner voice works, you need to understand how human thought translates into action. “Whenever we do any action, our brain makes a prediction of the sensory consequences of that action,” says Loevenbruck. Say you want to fetch a glass of water. “Your brain sends the appropriate motor signals to your hand, but it also generates a sensory prediction of the command,” she says. “Before you’ve even picked up the glass, your brain has made a prediction of what the motor command will do, which means you can correct for mistakes before you make an error.