I see...maybe it's more of a thing people with Extraverted Feeling do, then?
I guess that would make sense; people with Extraverted Feeling might be more prone to anthropomorphizing different ideologies in our brain, so it would be like envisioning some sort of dialogue with ourselves, with the other parts of our brain as its audience?
I think part of the reason why I myself do it is to try and convert my thoughts from a less visual/abstract format into a more verbal/concrete medium. I just realized that my thought processes are a lot less easily described as I previously gave myself credit for. For instance today, while I was attempting to explain to my dad (an ENFJ) the uncomfortably close connection between one of my acquaintances and his own father, I was at a loss for words. Any word that I attempted to use--"spoiled", "awkward", "uncomfortable", "dishonest"--failed to capture the true essence of the idea in my head; even now, I still can't seem to find any concrete evidence or concepts to back up my claims, other than from what I know about the general character of the acquaintance and his father... ._.;; Ah well.
Then again, I also tend to talk to myself whenever I feel like my thoughts need to be expressed, even when I have no suitable audience present. But instead of carrying on full-fledged conversations with myself, however, I would say it tends to come forth in random one-liners and declarations.
For instance, when I was doing research for a project about American Railway safety in the latter 19th Century and read the following line from an article about a horrific accident that occurred in 1871:
http://www.celebrateboston.com/disasters/revere-train-wreck-1871.htm said:
Passengers were trapped inside the splintered coach, with survivors having to pry off the roof to try and free victims. The steam boiler on the locomotive burst, with boiling water scalding to death some of the trapped passengers.
If I remember correctly, I was alone in my room when I read this, and my reaction was a mixture of cringing and squeamish laughter, soon followed by the verbal exclamation "Oh god, this is horrible! What were those bigwigs in engineering thinking when they designed that train?!" Which is more in line with what I was thinking in the first place when I brought up the subject of "thinking aloud".
((By the way, I meant to post this in the general MBTI forum, but I guess I posted it here by mistake! ^^;; But that's alright; I was more interested in hearing the perspectives of my fellow INFx brethren. The question itself arose due to writing, when I realized that one of my characters--who I think may be either an IxTP or INFJ in a Ni-Ti loop--was prone to thinking out loud.))