All of the following are TRUE about hallucination, EXCEPT:

A hallucination is a false perception that occurs in the waking state in the absence of a sensory stimulus. It is not merely a sensory distoion or misinterpretation, and it carries a subjective sense of conviction. A true hallucination appears to the subject to be substantial and to occur in external objective space. In contrast, a normal mental image is insubstantial and experienced within internal subjective space. Deafness, tinnitus, or blindness, usually in association with dementia or delirium, may determine the modality of hallucinations. There are six elements of hallucination:- They are substantial They appear in external objective space They are clearly delineated They are constant They are independent of the will of the observer Their sensory elements are full and fresh Ref: Nurcombe B., Ebe M.H. (2008). Chapter 4. The Psychiatric Interview. In M.H. Ebe, P.T. Loosen, B. Nurcombe, J.F. Leckman (Eds), CURRENT Diagnosis & Treatment: Psychiatry, 2e.