Archive for February 7th, 2013
Changizi on colourThursday, February 7th, 2013
I really appreciate how Mark Changizi approaches the subject of why we think the way we do. In a posting (here) he looks at colour.
I noticed that whenever the ‘hard question’ is discussed, the example that is used to illustrate its nature is colour. How do we explain colour and how do we tell if others see the same colours as we do? Changizi has an answer.
One of the reasons may be that the world can seem arbitrarily labeled in color, as if a painter dabbed over everything in order to make it beautiful and that naturally makes us wonder what a different artist might do…. Its an unfortunate intuition, one that seeps its way not only into the minds of laymen, but into our enhancement products and even the hallowed halls of philosophy. In trying to explain whats wrong with the intuition, let me begin with a thought experiment concerning a product that gives the wearer shape enhancement vision…. But few of us would be interested in using them for everyday wear. We want to see the world roughly as it is, not geometrically warped for no reason… Why should it be acceptable to warp colors but not shapes? Ill suggest here that its not acceptable – that once we appreciate the meaning of color it becomes apparent that we shouldnt arbitrarily engage in color distortion…. colors are just as steeped in meaning as are shapes, pitches, and all the other non-invertible dimensions of our experience. Ive argued in my research and in my book The Vision Revolution that our primate-variety color vision is optimized for sensing the spectral signals on skin when we blush, flush, blanch and signal other emotions. Our peculiar variety of color vision is just the needed peculiarity to sense oxygenation and concentration modulations in the blood under the skin, the physiological dimensions undergirding the colors we signal. …But I dont believe that the fundamental appeal of color is due to this arbitrary-splashes basis at all. Instead, it seems more likely that our love of color comes from the meaning of color, namely, that color vision for us primates is a deeply human and emotional sense. Color is evocative and aesthetic because its subject-matter concerns the most evocative states of the most important objects in our lives: other people. Thats why we find color so captivating. Its not because color floats above the world ungrounded, but, rather, because it is so deeply rooted in our psyche.
And, have you noticed that there is sometimes an assumption that our perception of colour is less mechanical than other senses. ScienceDaily (here) has a report from U of Rochester, Color Perception Is Not In The Eye Of The Beholder: It’s In The Brain. Williams and Hofer found large differences in people’s retinas but very small differences in their perception of colour. I am not sure that their results should have surprised them. There is a well known phenomena called colour consistency which ensures that the perceived color of objects remains relatively constant under varying illumination conditions.
But really, our development puts a lot of biological cost into vision eyes, the crossover of the optic nerve, a lot of processing prior to the optical cortex and then the size and complexity of the optic cortex. Can anyone think that this system is constructed by just slapping it together so that each person’s sight is a question of chance? Your red can be my green is nonsense. What is important is what the colour means to us.
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