I disagree with these 'absolutes'. I think there are many grey areas with dissociation, and there are times when what an alter feels is what the alter 'believes' - even though it doesn't match with the external reality - but it is definitely not because of psychosis. There have been many, many times when alters in this system have not been aligned with the external reality, and a 'diagnosis of psychosis' would have simply been plain wrong.

Current experts in the field are well aware of the overlap of dissociative experiences and symptoms of psychosis, with at least one study showing that people with DID can experience MORE first rank schneiderian symptoms than actual patients with schizophrenia!

For those that don't know:
Schnei·der first rank symp·toms
(schnī'dĕr),
those symptoms that, when present, indicate that the diagnosis of schizophrenia is likely, provided that organic or toxic etiology is ruled out: delusion of control, thought broadcasting, thought withdrawal, thought insertion, hearing one's thoughts spoken aloud, auditory hallucinations that comment on one's behavior, and auditory hallucinations in which two voices carry on a conversation.


I would be much more careful in suggesting that something so simple as an alter 'believing' something rather than 'feeling' it is evidence of psychosis.