Reality that matters

I once heard a programmer state that they could do a better job of vision that the brain does. This was because he would be accurate with the colour and brightness of the image so that two identical spots in a scene would be identical in the image of the scene. I was shocked at this misunderstanding of vision. Vision is not about this sort of accuracy, but a different and more important sort of accuracy.


A good example is at the start of a Wikipedia article on optical illusions (here) and it gives a definition, “an optical illusion is characterized by visually perceived images that differ from objective reality.” This assumes that the illusion is a less accurate idea of what is real than some other method. This is silly.


If I want to play chess on a black and white board (like in the Wikipedia page), I am interested in which squares are black and which are white – the nature of their pigment. I do not want this understanding of the board to change as a shadow passes over it. Not being able to see the constant ‘reality’ of the board would make playing chess very difficult. On the other hand I do not give a fig for the exact number of photons coming from any point on the board.


My being able to live in the world depends on seeing it with brightness and colour consistency. I want to see the tiger in the orange dusk light and also in the bluish moonlight. I am not interested in the actual amounts of each frequency reflected from the animal. I want to recognize the reality of a cat that does not change colour with the time of day. It should stay its real orange and black stripes.


So what is the objective reality that vision is trying show? It is the location, shape and chemical/physical nature of the surfaces of matter. The matter itself and not what may be registered by an instrument under some arbitrary condition. We want to know about the thing and not its reflection. Its reflection is only useful in what it can tell us about the thing. The thing is the level of reality that is useful to us.


I suspect the ‘kluge’ idea. Our memory would be less useful if it was stored in a permanent record like a video recorder. A video-like record would not be a good idea. It is not a fault that that our memories change. I do not want to have memories with the insight of a 10 year old when I am 70. Our memory is about understanding and learning, not about creating an accurate, complete autobiography.



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