In 1973 the French psychiatrist Henri Ey (19001977) defined hallucinations as follows. "The hallucination is an alteration of the process of objec-tification that results in the appearance of false objects in the subject s perception. The 'perception without an object to perceive constitutes the completest form of this error of the senses."
References
Ey, H. (1973). Traité des hallucinations. Tome 1. Paris: Masson et Cie., Éditeurs.
Dictionary of Hallucinations. J.D. Blom. 2010.