All of the following are features of hallucinations, except :
It is independent of the will of the observer
Sensory organs are not involved
It is as vivid as that in a true sense perception
It occurs in the absence of a perceptual stimulus
Hallucination is a sensory perception without external stimulation of the relevant sensory organ. Though there is no stimulation of sensory organs, hallucinations appear to arise from one of the external sensory organ.