JENNER'S DEFINITION OF HALLUCINATIONS
In 2006 the Dutch hallucination expert Jack A. Jenner defined hallucinations as follows: "Hallucinations are sensory perceptions without an object, without a demonstrable external stimulus."
References
Jenner, J.A., ed. (2006).Hallucinaties. Kenmerken, verklaringen, behandeling. Assen: Van Gor-cum.