madness said:There's really no such thing as "upside down" in an absolute sense, only relative to what we're used to.
Apparently it allows us to see a larger image.madness said:There's really no such thing as "upside down" in an absolute sense, only relative to what we're used to. Why then does our brain invert the image? What's wrong with leaving it the way it is?
Images on your retina are reversed. Your retina “sees” everything backwards. Your brain reorients you. This image reversal is an adaptive advantage providing us with tremendous peripheral vision and the ability to view objects much larger than just a few millimeters.
Images need to be reversed so we can see objects much larger than the size of our pupil and so that we may have peripheral vision.
Academic said:How do you figure? If my perceptions changed would the trees, rocks and objects in my surroundings conform to my changed perception? Most would say no. Our vision needs to correlate to our surroundings otherwise it would be of no use at all.
No, it would only be your visual experience.madness said:And to Evo: I'm not sure what you mean "match our physical experience". If it was upside down (compared to the way it is now), then that would be our physical experience.
Great example Academic.Academic said:Perception is not reality. If I perceive a rock flying in at the top of my field of vision then I duck. If I perceived that correctly I live, otherwise I die. The brain flips the image around so that when rocks actually fly at us we know to duck rather than jump. Why does the brain do that? Presumably because of natural selection.
Academic said:Perception is not reality. If I perceive a rock flying in at the top of my field of vision then I duck. If I perceived that correctly I live, otherwise I die. The brain flips the image around so that when rocks actually fly at us we know to duck rather than jump. Why does the brain do that? Presumably because of natural selection.
The image is upside down on the retina, and we have learned to jump with a projectile is high and duck when it is low. This is what 'brain inverting the image' means, it means that the brain knows when to jump and when to duck based off of the inverted image projected on the retina.Pythagorean said:...if the image were upside down, we'd just learn to jump when a projectile is up high and to duck when it's low, and our generalized model of up and down would be flipped from what it is now.
It does, apparently. I'm trying to find something about this study mentioned, I have found a different study for a longer duration.Pythagorean said:That doesn't quite settle it though. The point I think is being made in the OP is that if the image were upside down, we'd just learn to jump when a projectile is up high and to duck when it's low, and our generalized model of up and down would be flipped from what it is now.
I'm curious whether a system like the brain will always eventually correlate information in a way that reduces computational stress, so even if we wired ourselves so that we saw the image upside down, it would eventually correct itself if plasticity allowed.
The other part is handled in the optic part of your brain itself, and part of its job is to make images right-side-up. It does this because your brain is so USED to seeing things upside-down that it eventually adjusts to it. After all, it's a lot easier to flip the image over than it is to try and coordinate your hands and legs with an upside-down world! As a result, though, it is believed that for the first few days, babies see everything upside-down. This is because they have not become used to vision.
Your brain CAN be retrained though. In one psychological study, participants were asked to wear inverting lenses - lenses that invert the image BEFORE they get to your eye, so that when your eye inverts it, it's right-side-up. At first, everything appeared upside-down to the participants. But, after a few days, people began to report that everything appeared right-side-up! As a second part of the study, the people were asked to take the glasses off. Because they were now used to the lenses, their NORMAL vision appeared upside-down! Within a day, though, their vision returned to normal.
Not exactly, the inverting is a plastic process. When you wear special glasses that turn the world up-side-down, the image will invert after some time. When you take the glasses off, the brain adjusts again.Academic said:The image is upside down on the retina, and we have learned to jump with a projectile is high and duck when it is low. This is what 'brain inverting the image' means, it means that the brain knows when to jump and when to duck based off of the inverted image projected on the retina.
madness said:There's really no such thing as "upside down" in an absolute sense, only relative to what we're used to. Why then does our brain invert the image? What's wrong with leaving it the way it is?
lorax_2nd said:I believe you may be getting tangled up in the statement "the brain inverts [the] image". It is really more precisely stated as "the brain interprets the image as inverted". And that is simply because our brain has learned that a positive lens creates an inverted real image of an object.
In other words, your brain interprets direction on the retina to be inverted compared to an object in space. It does this because the optics of your eye (cornea/pupil/lens) have formed an image on your retina that is inverted compared to the object in focus. E.g., your brain has learned that when the image of your hand on your retina moves 'up' (towards the top of your head), your hand in front of your face is actually moving 'down' (towards your feet).
Hopefully I've understood your question well enough to clear it up for you.
Monique said:This is not true, since if you project the image the right side up, your brain adjusts as well. Academic, that's what I addressed in your quote, you start off by saying "The image is upside down on the retina", but in essence that has nothing to do with it.
lorax_2nd said:Monique, your statement quoted above is, well, annoying. It is annoying because it is carelessly vague. You say "this is not true". WHAT is not true? My whole post? The statement that a positive lens creates a real inverted image? I tried very hard to be precise and clear and define my terms and the problem I was solving, like a good physicist. You throw around pronouns like a 5-year-old.
You then follow that four word opacity with the non sequitur "since if you project the image the [sic] right side up, your brain adjusts as well." Hmmm, it may be true that your brain adjusts, but that invalidates NONE of my post. When your retina receives an inverted image, your brain interprets the image as inverted. What your brain would do with an upright image, I remained silent on.
Your final sentence is the kicker: "... IN ESSENCE has nothing to do with IT." (my capitals). What is it? Again, a pronoun that brings no clarity, only mud. And "in essence"? What essentiel element do you think you're distilling here?
I'm new to this forum, but what I'm reading here on this thread and on other threads erodes my eagerness to participate-- rather than people asking physics questions and getting straightforward, simple-to-understand physics answers, I'm seeing vagueness, confusion, lack of definitions, grand leaps into metaphysical speculation, and nonsense like "0 gravity". Is this a forum for chit-chat and casual conversation about aliens, or are we trying to help people understand the physical world around them?
madness said:There's really no such thing as "upside down" in an absolute sense, only relative to what we're used to. Why then does our brain invert the image? What's wrong with leaving it the way it is?
Academic said:The image is upside down on the retina, and we have learned to jump with a projectile is high and duck when it is low. This is what 'brain inverting the image' means, it means that the brain knows when to jump and when to duck based off of the inverted image projected on the retina.
Not quite. Vision processing is handled largely by the occipital lobe and then integrated into our spatial world model in the parietal lobe.Academic said:Whats the difference between 'adapting to it with muscle control' and 'aligning the map with the terrain'? Those are the same thing. They are each essentially setting 'y' to '-y'.
It's also not just about up and down: if you lie on your side to watch tv, it still looks like up and down rather than side to side. Your brain rotates the image to keep it oriented upright.Monique said:Not exactly, the inverting is a plastic process. When you wear special glasses that turn the world up-side-down, the image will invert after some time. When you take the glasses off, the brain adjusts again.
One of them your brain does automatically, the other you do consciously. As said before, if left and right are reversed, it takes an extra, consious transformation to coordinate your muscle movements with what you see. The brain eliminates the conscious transformation by doing it "behind the scenes".Academic said:Whats the difference between 'adapting to it with muscle control' and 'aligning the map with the terrain'? Those are the same thing. They are each essentially setting 'y' to '-y'.
Monique said:Not exactly, the inverting is a plastic process. When you wear special glasses that turn the world up-side-down, the image will invert after some time. When you take the glasses off, the brain adjusts again.
I think it is a really interesting concept, why do we all see our feet as "down", how does our brain learn to interpret the world. What happens if someone grows up in 0 gravity and comes to our world, would they have a concept of up and down and how would their brain adjust?
You don't because you don't have to because your subconscious brain has already taken care of it! That's the whole point!Academic said:****, I don't do either of those consciously!
Probably related: my young nephew has crossed eyes and according to the doctors, if not fixed relatively early, they will be permanently crossed and he will never develop depth perception. It is as if your brain is still writing its programming when you are an infant, but once you get to be a few years old, the programming is set.DaveC426913 said:There have been experiments to test these kinds of things. Animals (kittens) were reared in an environment where there were no vertical or horizontal edges to anything. Once put back in a normal world, the kittens were completely disoriented.
Indeed it does, but it can only "correct" the image up to a certain angle.russ_watters said:It's also not just about up and down: if you lie on your side to watch tv, it still looks like up and down rather than side to side. Your brain rotates the image to keep it oriented upright.
russ_watters said:You don't because you don't have to because your subconscious brain has already taken care of it! That's the whole point!
But if you want to see what it's like to have to do it consciously, put a mirror behind your head and another in front of you and try to trim the hair on the back of your neck! I cut my own hair, but it is a difficult skill to master.
That is really interesting.DaveC426913 said:There have been experiments to test these kinds of things. Animals (kittens) were reared in an environment where there were no vertical or horizontal edges to anything. Once put back in a normal world, the kittens were completely disoriented.
russ_watters said:Probably related: my young nephew has crossed eyes and according to the doctors, if not fixed relatively early, they will be permanently crossed and he will never develop depth perception. It is as if your brain is still writing its programming when you are an infant, but once you get to be a few years old, the programming is set.
abstract said:Functional maps arise in developing visual cortex as response selectivities become organized into columnar patterns of population activity. Recent studies of developing orientation and direction maps indicate that both are sensitive to visual experience, but not to the same degree or duration. Direction maps have a greater dependence on early vision, while orientation maps remain sensitive to experience for a longer period of cortical maturation. There is also a darker side to experience: abnormal vision through closed lids produces severe impairments in neuronal selectivity, rendering these maps nearly undetectable. Thus, the rules that govern their formation and the construction of the underlying neural circuits are modulated-for better or worse-by early vision. Direction maps, and possibly maps of other properties that are dependent upon precise conjunctions of spatial and temporal signals, are most susceptible to the potential benefits and maladaptive consequences of early sensory experience.
We should also keep in mind that we are products of evolution from simpler forms. We can only have gotten where we are now by way of those simpler forms.madness said:I like Pythagorean's idea that it reduces neural computation...
Monique said:Why would there be more neural computation, if your neurons are accustomed to a certain reference? In my example of the microscope the motor movements get accustomed really quickly to the inverted image.
Pythagorean said:The idea is that the adaptation you mention serves to reduce surprise to the organism, which reduces neural computation by reducing information entropy.
DaveC426913 said:Are we seriously suggesting that, in the evolutionary past, animals saw the world upside down and thus used an inordinate amount of processing to navigate their world, and then one day, their brains "adapted" by flipping the image over because it was more efficient?