They see or hear things that do not exist in physical reality. But I would argue that their illusions are actually real things. I maintain that illusions are real. Note: They don't have to be real to be real. A lie, in fact, is a real thing. That said, even from the materialist view that consciousness is an illusion produced by the brain, then the illusion has a physical reality. That is, even from the materialist point of view, the illusion has a physical reality in the neural connections that fire in the brain in certain ways. It has a physical reality. From the non-materialist point of view, even if there were no physical reality in the schizophrenic's illusion, his illusion has a reality as thought in consciousness! So, I just proved that even an illusion is a real thing. From the relativist point of view, truth or falsity depends on the perspective and beliefs of the observer. For the absolutist, truth or falsity depends on sensible evidence and reason. In any case, the illusion is real, even if false. It is real as abstract or as neural