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Medical Inverting your Vision

  1. Jun 13, 2012 #1
    I could have put this in the biology forum, but decided it has too strong a philosophical slant (as my questions always seem to). I recently read that the experiment where people who wore vision-inverting glasses having there vision eventually flip is a myth. This reminded me of a question I always had on the issue. What does it even mean for your vision to flip, and what does it mean when people say your brain inverts your vision from your eye? Inverts it relative to what? It seems to me that it is a meaningless question since there is no reference for up and down other than your experience of it. On the other hand, wearing inverting glasses causes the experience of having your vision flipped, but is this just relative to our auditory and proprioceptive cues?
     
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  3. Jun 13, 2012 #2

    Evo

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    This has nothing to do with philosophy.
     
  4. Jun 13, 2012 #3
    Well since it is a question about subjective experience it kindof does...
     
  5. Jun 13, 2012 #4

    Evo

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    Not for our rules.
     
  6. Jun 13, 2012 #5

    jtbell

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    The lens of your eye produces an inverted image of the outside world on your retina, like the inverted image that you can project onto a sheet of paper using a magnifying glass. Your brain "inverts" your perception of this image so that you perceive the outside world as "right side up."
     
  7. Jun 13, 2012 #6

    lisab

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    I don't think that's what madness's question was.

    We label our world "right side up" because it's all we've ever known. But suppose our brains did not invert the image. We would still call what we see "right side up", since that new image would then be all we've ever known. So, why does the brain bother to invert the image?

    Somehow I think we've had a thread or two on this before....
     
  8. Jun 13, 2012 #7

    Evo

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    I believe this is the study madness is referring to.

    http://wexler.free.fr/library/files...udy of adaptation to inverting spectacles.pdf
     
    Last edited: Jun 13, 2012
  9. Jun 13, 2012 #8
    Six to ten days? Are they kidding? I'd expect six to ten years for vision to invert in a fully formed adult if ever.

    Calling it a "myth" after a ten day experiment is like declaring Bigfoot a myth after a hard two-hour stare into the woods. Even Bigfoot skeptics would say you haven't looked hard enough to rule it out.
     
  10. Jun 13, 2012 #9
    It should be sufficient to debunk it because the original and supporting claims all said six/seven days:

    What's interesting to me is that my eyes adjusted to the large print at the pdf in the course of reading one paper such that when I came back to PF the print here looked microscopically tiny.
     
  11. Jun 13, 2012 #10

    atyy

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  12. Jun 13, 2012 #11

    russ_watters

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    Yes, we've had this discussion before.

    The image is inverted because there really is an up and a down. It is more than a matter of convention, it is a matter of body orientation. Your forehead is above your eyes and your chin is below. If you don't flip the image, you'll see that reversed. It is similar to looking at yourself through two mirrors - you can adapt, but it never is actually correct.
     
  13. Jun 13, 2012 #12
    There's no objective up or down. People at the North Pole feel just as normal as people at the South Pole, despite the fact they're in 180 degree conflict about Up and Down. There is objective centripetal acceleration toward the center of the earth, but that direction is specific to exactly where you are on the earth, and different in all locations.

    The problem created by inverting glasses is that they selectively take one sense and put it at odds with the other senses, as the Opening Poster suspected.
     
  14. Jun 14, 2012 #13

    Ryan_m_b

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    Yes there is, "down" is the direction that gravity is pulling you and "up" is the opposite direction. That is an objective definition.

    In addition when we're talking about bodies we do have measures of orientation that we can use to determine the "bottom" and "top" of a body even if it changes position i.e. I can still say that on my body my eyes are above my chin even if I am standing on my head.
     
  15. Jun 14, 2012 #14

    Ryan_m_b

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    It means that even when you are orientated with your inferior (anatomical bottom e.g. feet) pointing in the direction that gravity is pulling you and your superiod (anatomical top e.g. head) pointing in the opposite direction your vision disagrees by placing everything in reverse e.g. when looking at another human it seems that their inferior is pointing in the direction that your superior is.
    Exactly that, the brain takes the image the eye is seeing and flips it so that everything sensed at the top of your field of vision is percieved at the bottom.
    Relative to your body. The images your brain percieves is inverted to the image your eye senses.
    See my first comment replying to zoobyshoe.
    I'll have to think about this more but even if you flip every sense you won't be flipping direction so relative to the outside world you will be dead wrong trying to place things e.g. if you hear a sound to your right you will percieve it to your left and therefore move the wrong way. Unless sense of direction gradually changes.
     
  16. Jun 14, 2012 #15
    "Exactly that, the brain takes the image the eye is seeing and flips it so that everything sensed at the top of your field of vision is percieved at the bottom."

    I'm not sure this makes sense. You're brain has a retinotipic mapping of the retina, bit the orientation of the mapping on the surface of the cortex has no meaning. I'm not sure that the brain does flip the image at all. Your retina will have your feet at the top and your forehead at the bottom (so to speak), but when it gets to the brain it has no concept of where the forehead of feet actually were relative to the retina.
     
  17. Jun 14, 2012 #16
    This is true for the physical world, but you need to consider only the information your brain has access to. As I said, the information entering the brain from the retina is simply a topographic map of light entering the retina. The brain can't tell which way is "really" up or down from this. The reason being that there is no up or down in this sense. This is why I'm led to believe that it is not true that your brain inverts your vision.
     
  18. Jun 14, 2012 #17
    Up and Down are determined at each spot on the earth by the centripetal acceleration of gravity, yes. They are not a matter of body orientation as Russ said.

    These terms were created to be independent, when needed, of the centripetal acceleration of gravity, so that when speaking of the dorsal features of a fish, for example, they remain dorsal regardless of the orientation of the fish with respect to the earth. The dorsal aspects of a fish are with respect to the fish and will remain dorsal even in outer space. Your head remains superior to your feet even if you are upside down with respect to the earth because the term "superior" is understood to be disconnected from gravity.

    When, therefore. you substitute "above" for "superior" you make a mess of the terminology and end up saying nonsensical things like your eyes are still above your chin when you're standing on your head. They're not. They are superior to your chin, but below it. "Above" and "below" are relative to external references. "Superior" and "inferior" are not relative to external reference points. The whole point of creating that terminology was for it to be independent of external reference points.
     
  19. Jun 14, 2012 #18
    The image projected on the retina is inverted from the external world. That's just a fact of optics. Whether or not the signals are re-inverted could be determined, I would have thought, by the orientation of the visual field maps in the brain. But, a quick google brought up this study:

    http://www.ncbi.nlm.nih.gov/pubmed/17964252

    which, as usual with the brain, shows it's quite complicated.

    This sentence:

    suggests that some maps are inverted ("alternate in visual field sign") and some aren't, but I'm not sure what they mean by "visual field sign".

    If you look at a map of touch sensation it's clear it's not a literal little human shaped homunculus as it's sometimes represented. Therefore, there is probably no absolute need for the maps of the visual field to be literally inverted to conform to the external world in order for us to be conscious of them the way we are.
     
  20. Jun 14, 2012 #19
    "Whether or not the signals are re-inverted could be determined, I would have thought, by the orientation of the visual field maps in the brain."

    But you haven't explained what it would mean for the signals to be "re-inverted". Clearly, the physical orientation of the retinopic map on the cortex is unimportant - what matters is the pattern of wiring. In this sense, the only way it can be inverted or not is relative to other topographic maps like auditory and somatosensory. Therefore, your brain can't flip your vision relative to the world or to your retina.

    I also think you may have misunderstood the study you cite. The visual cortex is made up of orientation selective cells which form a striate patterned structure on the back of the brain. In general neighbouring cells have neighbouring orientation selectivity, but there are sometimes also pinwheels and fractures in the map where the orientation preference changes discontinously. I think this is what your quote is referring to.

    Edit: I'm actually not sure what that quote is referring to. Although what I wrote in the last paragraph is true, it might not be what they are talking about. However I'm pretty sure its talking about feature preferences within and not between maps.
     
  21. Jun 14, 2012 #20
    I googled and found there are cases of pathological inversion of vision:

    http://www.neurologia.com/pdf/Web/4403/x030157en.pdf [Broken]

    http://www.ncbi.nlm.nih.gov/pubmed/3064969

    Indeed, I recall reading that Van Gogh reported to his doctor that he had an incident preceding a seizure during which one half of his visual field suddenly became inverted.

    This suggests the brain does, indeed, automatically perform some inversion of the image that lands on the retina, and that they are reverted with respect to that image on the retina, a function that can be subtracted by disease. By "the brain" I could be referring to anything in and of the brain. Something is acting like a lens, a lens that can fail.
     
    Last edited by a moderator: May 6, 2017
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