Charles Fernyhough

We've shown you can do it.

Not just us, teams all around the world have shown you can study this stuff.

You can have a science of it.

Well, if you watch any small child, you're really likely to see them talking to themselves.

Yes.

So when kids are talking to themselves out loud, we call that private speech.

And the idea is that it's the precursor.

It's the thing that comes before inner speech.

So the inner speech that you and I probably experience, or may not, where that comes from developmentally is from private speech.

And in turn, that private speech came from the social dialogues that kid enjoyed when they were growing up.

So, you know, talking to caregivers, other adults, other children, and gradually internalizing those conversations, they become conversations with the self.

Yeah, exactly.

That is the theory of a great Russian psychologist called Lev Vygotsky who was writing this stuff about 100 years ago.

His work has become increasingly influential in recent years and it's a really simple, neat little theory that nobody's got to the bottom of yet because it is so rich.

It has such implications for the way our minds work.

Well, as you'd expect, you see the language systems that we know about, mostly lateralized onto the left hemisphere.

A bit towards the front called Broca's area, which is often involved in producing complex action patterns.

A bit further back called Wernicke's area, which is responsible for processing speech, including speech from other people.

Those two areas create a kind of resonating loop, which always shows up when we ask people to speak to themselves or out loud in the scanner.

These days, it's going to be an MRI scanner when we're doing fMRI research on the topic.