…[I]f the theory of consciousness presented in this paper is correct, then all the contents of consciousness — including our visual sensations — lie in a space, or brane, of their own outside the physical universe. Normal perception, in this theory, is mediated by the causal chain
object–photon–retina–brain–(cross to a new brane)–visual field.
Hallucinations involve only the last part of this causal chain
brain–(cross to a new brane)–visual field. 
- http://www.newdualism.org/papers/J.Smythies/Smythies-JCS2003.htm [↩]