I've been asked that question by shrinks and I've always thought that it was a dumb question.

When I've been around a person who was truly hallucinating, the person had no idea that what they "perceived" was not there. Usually, the patient tries to get other people to admit that they see it too. I've only seen this in hospitalized patients who were extremely ill. When they recovered, they usually had no memory of the hallucination. A few times, the patient would remember the odd experience. The patient would say, "It doesn't make sense, but I still remember it like it really happened."

I guess the real question is whether some psychiatric patients can have visual hallucinations and, somehow, realize that they are having hallucinations. Can they realize it during the hallucination . . . or after the event? I've never seen firm evidence of that being true. Maybe the pdocs have, but I'ld like to know where.