> I have heard that babies do not realize that their thoughts are private and they assume that thinking by itself is a form of communication.

I've occasionally noticed other adults say odd things, followed a bit later by "oh crap, I said that out loud?", or more frequently people will "think out loud". I've also noticed once or twice (I think I might have to be fairly well distracted for this) that someone would say "hi" in passing and I'd say "hi" back... and then a few steps later realize I hadn't actually said anything, just thought it at them (rather like how on a sizable fraction of conference calls, there's at least one person who forgets to un-mute their phone when talking).

...also my wife sometimes says I'm supposed to be able to read her mind on a number of topics, but I think that's different.