The vast majority of people have an ongoing conversation with themselves, an inner voice, that plays an important role in their daily lives. But between 5-10 per cent of the population do not have the same experience of an inner voice, and they find it more difficult to perform certain verbal memory...
I have a non-verbal inner voice which gives meta-commentary on my verbal inner voice. If I want to think about what I'm thinking, that's what is going on.