Replaying or rehearsing conversations out loud- i.e. talking to yourself [is a] (very common sign) [of schizophrenia].
Looking at the site it's not clear who edits it (or what their credentials are)... so is this claim supported by research, i.e. is talking to oneself loudly a very common sign of schizophrenia?
And is it so irrespective of the content of the talk? E.g. talking to "oneself" as if having a conversation with an imaginary person [different than oneself] seem somewhat different to me (and indicative of hallucinations) in contrast with clearly self-directed self-talk, e.g. as described in the first paragraph of a NYT article of someone wondering out loud in a supermarket. Or is it simply the case that so few people talk to themselves loudly so that the group (of loud self-talkers) is dominated by those who have schizophrenia? (About 75% of people with schizophrenia experience auditory hallucinations.)
I also found that
Self-talk [and by this the article means loud] and behavior rituals were found to be common behavioral features in adults with Down syndrome, and in most instances, were not a sign of a psychiatric disorder.
But then the number of people with Down syndrome is only about 1/12 of those with schizophrenia.