Direct Perception

• Direct Perception is incredible because it suggests that we can have experience out beyond the sensory surface, in violation of everything we know about the causal chain of vision.

• Visual illusions are an embarrassment for Direct Perception because the illusory edges and surfaces appear out in the world on the page where the stimulus is printed, although they are obviously the result of processing in the brain.

• The phenomena of dreams and hallucinations are also problematic for Direct Perception because they demonstrate the capacity of the brain to construct complete virtual worlds, a capacity which must surely be employed also in normal spatial perception.

• Finally, Direct Perception offers no clue as to how an artificial vision system could possibly be endowed with the kind of external perception that we observe in visual consciousness.

Indirect Perception

• Indirect Perception is also incredible, for it suggests that the world that we see around us is actually inside our head. This can only mean that the head which we have come to know as our own, is not our true physical head, but merely a miniature perceptual copy of our head inside a perceptual replica of the world, all of which is contained within our physical head.

• Stated from the internal phenomenal perspective, beyond the farthest things that we can perceive in all directions, i.e. beyond the walls, floor, and ceiling of the room you see around you, is the inner surface of your true physical skull. And beyond that skull is an unimaginably immense external world of which all this that you see around you here is merely an internal virtual-reality replica.

  The existential vertigo occasioned by this mental image is so disorienting that only a handful of researchers have seriously entertained this notion, or taken it to its logical conclusions.

• Indirect Perception suggests a three-dimensional volumetric imaging mechanism in the brain for which no direct neurophysiological evidence has been found.

Projection Theory

• Projection Theory is also incredible because no medium or carrier has ever been discovered projecting information outward from the brain. The flow of visual information is exclusively uni-directional: from the world, through the eye, to the brain. The external world and its perceptual replica cannot be spatially superimposed, because one is inside your head and the other is outside.

• The pheomena of dreams and hallucinations are also problematic for a Projection Theory for they produce an experience much like normal perception, and yet for some reason they are not projected but remain internal to the brain.

• Finally, Projection Theory offers no clue as to how an artificial vision system could be constructed to project as in our own conscious experience.