I was wondering if hallucinations could radically override real external stimuli. After all every sensory organ responds to external stimuli, but when a hallucination occurs, I suppose, the external stimulus and the false stimulus (hallucination) combine. Or do they?
For example: Let's say I'm looking at an apple and in the meantime I hallucinate an orange, theoretically the informations about the apple should still reach my brain together with the hallucination of the orange, therefore I should be able to see the apple and the orange at the same time.
Something analogous happens in the phenomenon of afterimage where the photochemical activity in the retina continues with less intensity even without the original stimulus. The new and the old stimuli combine.
Is that what happens during hallucinations too?