How do some people think/speak inside their head while others can’t?

Question

How do some people think/speak inside their head while others can’t?

In: Biology

Answer 1

Im guessing that people who are more sociable and talk more often wouldn’t really need to think speak so they just don’t, and people who do think speak talk less or listen to conversation less so to make themselves not bored they speak to themselves but in their head so no one else hears and it is less effort.

This is just me guessing. I could be incorrect.