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Amira .

Everything We Knew About Human Vision is Wrong by Mark Changizi Tells Us Why ... - 0 views

neuronarrative.wordpress.com/...hor-mark-changizi-tells-us-why

mind & brain Neuroscience science cognition & relativity Cognition perception relativity cognitive science philosophy

shared by Amira . on 15 Jan 11 - Cached
  • I call myself a theoretical neurobiologist, more generally, and I have had a number of non-vision research directions, including, for example, the shape and evolution of the brain, and why animals have as many limbs and digits as they do.  Some of these research directions were central parts of my first book, The Brain from 25,000 Feet.
  • You mention in the book that reading and writing are relatively recent advances in human development, and yet we take for granted that we “see” and understand words, as if our brains were simply meant to see and understand them.  What’s really going on that allows us to make sense of symbols on a page—and why can we do this at all?
  • the invention of writing is only thousands of years old. In addition, for most of us, our grandparents, great grandparents or great great grandparents didn’t read at all. Writing is much too recent for our brains to have evolved to have reading mechanisms.
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  • The solution is that culture made writing easy on the eye, by shaping letters to be what the eye likes. The idea that culture shapes our artifacts to be good for us is not new. What’s new here is a specific hypothesis for what writing should look like in order to be good for us.
  • To be easy on the eye, writing needs to “look like nature,” just what our illiterate visual systems are fantastically competent at processing. The trick of that research direction was making this “writing looks like nature” idea rigorous, and coming up with ways of testing it. I show that there are certain signature visual patterns found in nearly any natural environment with opaque objects strewn about, and that these signature patterns are found in human writing. In short, writing has evolved so that written words look like visual objects.
  • When light hits our retina, what our brains would like to do is instantaneously generate a perception of what the world looks like. Alas, our brain can’t do this instantaneously. Our brains are slow. It takes around a tenth of a second for your perception to be built, and that’s a long time when you’re moving about. If you perceived the world the way it was when light hit your eye, you’d be having a tenth-of-a-second old view of the world.
  • First consider illusions like those I discussed above. One often feels as if what we see is due to some kind of direct “reading” of the real physical world. But our brain can’t just passively react to the incoming stream of visual information, lest it have an old perception of the world. Instead, it must actively generate a guess about the near future, which helps drive home that our perception is always an internal concoction by your brain. In fact, most of the input to your visual system is feedback from that very visual system.
  • Second, consider forward-facing eyes and binocular vision. When we see with two eyes in the same direction, we have one unified visual perception. We have what feels like a single viewpoint, one that is emanating roughly from a point between our two eyes. Furthermore, our single viewpoint is always filled with two copies of the world that you hardly ever notice. When you fixate on something out in front of you, then objects nearer and farther split into two perceptual copies, each rendered as transparent in your perception.
  • This allows you to see objects, and to see beyond them. For example, you can see your own nose from opposite sides at all times, but it is rendered as partially transparent and so does not block your view of the world beyond. The more one analyzes the phenomenology of binocular vision, the stranger it seems. But it doesn’t feel strange, because these are perceptual facets that our brain knows how to interpret. They are needed as part of your unified view of the world in order to incorporate the fact that it is really built out of two views of the world. Although, in a sense, you are perceiving fictions, they are fictions that allow you to more veridically see the world.
  • And, lastly, consider color vision. This is a case that helps us better understand that it is not so much whether you see the world as it is, but how much of the world’s reality your are privy to seeing. Colors are primarily about the underlying emotions and states of those around us, as seen through the window of skin, and the physiological changes in the blood. The spectrum of skin is complicated, but it varies over two dimensions that matter most for sensing the states of others, the concentration and oxygenation of skin.
  • The question is, what does the concentration and oxygenation of blood in the skin of others “truly” look like? Or, what do the emotions those blood variables signify “truly” look like? The interesting thing here is that these blood dimensions and these emotions are “really there”, but there is little sense to what their “real look” might be. Colors serve the role of what they look like, but does red really look like oxygenated blood or really look like anger? I’m not sure this is a sensible question. What matters is that that qualitative perceptual state is given a meaning or association to us, and so serves its purpose.
  • Amira . on 15 Jan 11
     
    For theoretical neurobiologist and author Mark Changizi, "why" has always been more interesting than "how." While many scientists focus on the mechanics of how we do what we do, his research aims to grasp the ultimate foundations underlying why we think, feel and see as we do. Guided by this philosophy, he has made important discoveries on why we see in color, why we see illusions, why we have forward-facing eyes, why letters are shaped as they are, why the brain is organized as it is, why animals have as many limbs and fingers as they do, and why the dictionary is organized as it is.
Amira .

The Contents of Perception (Stanford Encyclopedia of Philosophy) - 0 views

plato.stanford.edu/...perception-contents

cognition & relativity cognitive science mind & brain psychology philosophy

shared by Amira . on 15 Jan 11 - Cached
  • Three main questions will be addressed in this entry. First (Sections 1–2), what are contents and what is their relation to experiences? Second (Sections 3–7), which contents are contents of experience? Finally (Section 8), in virtue of what do experiences have contents, when they do?
  • Amira . on 15 Jan 11
     
    In contemporary philosophy, the phrase 'the contents of perception' means, roughly, what is conveyed to the subject by her perceptual experience. For example, suppose you are looking into a piano at the array of hammers and strings. There will be a way these things look to you when you see them: they will look to have a certain shape, color, texture, and arrangement relative to one another, among other things. Your visual experience conveys to you that the piano has these features. If your experience is illusory in some respect then the piano won't really have all those features; but even then, there will still be something conveyed to you by your experience. Three main questions will be addressed in this entry. First (Sections 1-2), what are contents and what is their relation to experiences? Second (Sections 3-7), which contents are contents of experience? Finally (Section 8), in virtue of what do experiences have contents, when they do?
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