An example of a hallucination is a vision of a pool in a hot desert.
It was not unlike any night's nocturnal hallucination.
In fact, she felt angry, and she wanted to see the galley to confirm this all wasn't an elaborate hallucination.
This wouldn't be true with a purely psychological phenomenon like a hallucination.
Sensory Automatism is the term given by students of psychical research to a centrally initiated hallucination.