Is the visual world an illusion?

Alva Noë, ‘Is the Visual World a Grand Illusion’ (Journal of Consciousness Studies, 9, No. 5–6, 2002.)  questions whether we can know that things are as we believe we experience them as being. He argues that we have radically false beliefs about what our perceptual experience is like.

For Noe, perceptual consciousness is a kind of false consciousness; a sort of confabulation -  a  filling  in gaps in one's memory with fabrications that one believes to be facts

So what is the character of our perceptual experience? According to a conception of visual experience that has been widely held by perceptual theorists, you open your eyes and — hey presto! — you enjoy a richly detailed picture-like experience of the world, one that represents the world in sharp focus, uniform detail and high resolution from the centre out to the periphery. Let us call this the snapshot conception of experience. Empirical investigation of the nature of vision takes its start from the snapshot conception.

But visual theory researchers questions how is that how it is we come to enjoy such richly detailed snapshot-like visual experiences when our actual direct contact with the world in the form of information on the retina is so limited. How are we able to enjoy the impression of seamless consciousness of an environment that is so detailed, continuous, complex and high-resolution?

The orthodox strategy is to suppose that the brain integrates information available in successive fixations into a stable, detailed model or representation. This stable representation then serves as the substrate of the actual experience. According to this orthodox approach, vision just is the process whereby the patchy and fragmentary bits of information on the retina are transformed into the detailed stable representations underlying actual perceptual experience

However recent work in perceptual psychology challenges this traditional framing of the problem for visual theory by questioning whether we really enjoy the sort of richly detailed, snapshot-like visual experiences we think we do.

If we do not enjoy such experiences, then we are not faced with the problem of how the brain gives rise to them. Indeed, from the standpoint of the visual theorists, the central problem of visual theory is not: how do we see so much on the basis of so little? It is, rather, why does it seem to us as if we see so much when in fact we see so little.

For decades people have clalmed that the most striking things about consciousness is its continuity’

Dennett writes in response: (Dennet 1989, p. 119).

“This is utterly wrong. One of the most striking features about consciousness is its discontinuity — as revealed in the blind spot. The discontinuity of consciousness is striking because of the apparent continuity of consciousness (1991, p. 356).

So what is the argument and where is the evidence that experiences are not what they seem to be? The locus classicus is Dennett’s discussion of filling in at the blind spot (Dennett, 1991, pp. 344–56).

Blind spot test

Demonstration of the blind spot
O		X
Instructions: Your face should be a few fingers away from the screen. Close the right eye and focus the left eye on the X. Now move away from the screen slowly, and at one point the O will disappear. This will happen approx. when the screen is about 25cm away (3x the width of this diagram). As you move further away, the O will reappear. If you close your left eye and look at the O, the X will disappear over a similar range.

It would appear that what you appear to see is not what you actually see.