@BroDrillard @Momther None that I have seen, there is a lot of things that aren't studied for political reasons. I had quite a few tense convo's with my professors back in school over asking questions like that.
But that makes sense, people who just spew their thought stream out probably can't can't process it internally.
The closest thing I have seen to what you are a talking about is people with frontal lobe damage. The human brain is constantly generating responses to stimuli and the frontal lobe processes and manages those responses. When people get frontal lobe damage they experience a severe loss in self restraint and start saying and doing things they would normally keep under control or to themselves.
As a side note the frontal lobe is the last part of the brain to fully develop and has big difference in neuron density between races, sexes, and even individuals within a group.
https://journals.plos.org/plosone/article?id=10.1371/j...
I have to dig through my old folders to find it since google isn't being helpful but the tl;dr is that with the exception of some Asians and middle eastern people almost all non Whites have a no FUNCTIONAL inner monologue except for the upper 1% of their populations.
Also, more than 90% of WHITE women don't either. Funny enough, Asian women had slightly higher numbers than White women (only a couple %).
Some people "hear" their own thoughts but they don't internally debate their own actions, which most studies conflate.
What that leaves is ~40% of White men and a handful of middle easterners and Asians; tally it up and account for population sizes and you have roughly 5%.
EDIT:
It actually makes sense if you think about how human civilization evolved, an inner monologue was only useful to tribal leaders for most of human existence. Higher thinking isn't always a useful trait.