Thursday, 19 September 2013

What ghosts tell us about consciousness

ShadowWhy do I keep seeing the door ghost (door what?)? The answer to this simple question may have surprisingly profound implications for consciousness.

Here's the difficulty. I know the door ghost is a misperception of my own hand, reflected in a frosted glass window and seen in peripheral vision. It appears frequently, particularly when I'm not actively looking for it. But here's the thing; I KNOW it is only my own hand! Even when I am actually watching the ghost I am fully aware I am actually seeing my own hand. And yet an amorphous dark figure still stands there, slightly menacingly, just behind me. If I move my hand or change my angle of view, the figure disappears instantly. So, if I KNOW it is only my hand, why do I keep seeing it as a shadow ghost?

This is where consciousness comes in. The 'I' that knows I am misperceiving is clearly the conscious part of my brain. But, clearly, the unconscious part of my brain never learns from its perceptual error. So I keep seeing the ghost. It suggests that the conscious part of the brain cannot directly affect what is going on in at least some parts of the unconscious bit.

But why doesn't the unconscious part of my brain ever learn about its mistake for itself? We know that unconscious bit of the brain is perfectly capable of learning stuff. When you learn to ride a bicycle, for instance, it is an unconscious process whereby you learn how to manipulate your muscles in such a way that you maintain balance when riding. Interestingly, even when you can consciously influence a skill that has been developed unconsciously, it tends to cause problems. Ask a golf player to concentrate on just how they are physically playing a shot, while they are actually playing it, and they tend to perform less well than usual.

So why can't my brain learn that it is misperceiving? My guess would be that the perception system in the brain deliberately does not remember every mistake it has made in the past. If it did, it would have to 'look up' all previous mistakes in memory all the time, to check for errors, during normal perception. And that would probably slow down the business of perception enough to become a serious problem. In the trade off between accuracy and speed, the brain chooses speed.

This means that a witness who is misperceiving a ghost can see it again and again, every time they are in the right position and in appropriate lighting conditions. This will serve to confirm, for the witness at least, that they really are seeing an objective ghostly figure and not simply imagining it or hallucinating. However, while it is quite true that they are neither imagining or hallucinating, neither are they seeing an objective figure. And if the witness thinks they cannot be fooled by the same misperception twice, they are wrong.

And the profound bit? Well, we tend to think of consciousness as 'running the show' in the brain. It is the bit we think of as 'me', the seat of awareness, the essence of being. But this implicit assumption that consciousness is 'in charge' of the brain appears to be wrong. There are bits of the brain's unconscious workings that we apparently cannot affect. When people say 'I know what I saw', they are just wrong. They are actually consciously experiencing an edited version of reality, filtered by the unconscious part of their brains according to rules most people are not aware of. And sometimes, as in some apparent paranormal reports, that edited version is a long way from objective physical reality.

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