Why does our brain invert the image received from our eyes?

[madness]

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]

There's really no such thing as "upside down" in an absolute sense, only relative to what we're used to.

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.

 

[Evo]

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?

Apparently it allows us to see a larger image.

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.

http://retinaeyedoctor.com/2010/03/eye-images-reversed-on-retina/ In answer to "why not leave the image upside down" Our brain flips it back so that what we see matches our physical experience.

 

[madness]

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.

They wouldn't need to change, I don't see your point. The world doesn't "look like" anything independently of how our brains choose to model it. I don't see how it is any less correlated before it's inverted - it's just that we're used to it this way.

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.

The part about having a larger field of vision is very interesting.

Edit: Although it seems the larger field of vision only comes from the pinhole aspect and not the actual reversing at the end, although I may have misunderstood.

 

[Academic]

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.

 

[Evo]

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.

No, it would only be your visual experience.

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.

Great example Academic.

 

[Pythagorean]

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.

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.

 

[Academic]

...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.

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.

 

[Evo]

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.

It does, apparently. I'm trying to find something about this study mentioned, I have found a different study for a longer duration.

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.

http://www.physlink.com/education/askexperts/ae353.cfm

 

[Monique]

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 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?

 

[Academic]

Sure, the inverting process is plastic. That is completely consistent with my quote, isn't it?

The brain figuring when to jump and when to duck is the brain inverting the image.

 

[lorax_2nd]

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?

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]

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.

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.

http://www.cns.nyu.edu/~nava/courses/psych_and_brain/pdfs/Stratton_1896.pdf"

 

[Academic]

Has nothing to do with what? I thought that's what this post was about, the image being projected upside down on the retina.

So you can change that with lenses and make the image right side up on the retina. In that case the brain then inverts the image again to make it consistent with reality. It re-calibrates your motor movements to properly correlate with your visual observations The question is why does it do that, and the answer is so that it can cope with its surroundings. (that is, so it can jump or duck in the right situation)edit - After re-reading this thread I think an issue is the perceived difference between the brain inverting the image and its calibration with your body to move correctly. Its almost like the question is why does the brain invert the image rather than recalibrating motor movements. My answer would be, those are the same thing.

 

[lorax_2nd]

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.

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?

 

[Monique]

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?

In this forum we treat other members with respect, I suggest you adjust your attitude.

 

[Andy Resnick]

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?

I think you are confusing the retinal image with 'visual perception'. Yes, the image on the retina is inverted. By the time the nerve impulses have passed the optic chiasm, the lateral geniculate nucleus, into V1 and then back out to the extrastriate cortex, so much processing has occurred that it hardly makes sense to even reference back to the retinal image.

For example, an elementary unit of visual perception is an oriented bar, not a point. We do not yet know how we extract information (beginning with 'up' and 'down' all the way through object recognition) from the retinal image.

At this point in time 'why?' is not a good question to ask. Better to ask 'How?'.

 

[Pythagorean]

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.

Yes, but we're talking about the perceived image. As Monique is saying, the retina has nothing to do with it, it was merely the spark that triggered the OP's question. The question itself pertains to the image as processed by the occipital and parietal lobes (at the least).

So to restate my post, if the image were perceived were upside down, we'd have learned how to adapt to it with muscle control. But I assume (and em encouraged by responses in this thread) that this would be computationally expensive to navigate through the world like this, so the brain (or the genetic basis of it) already long ago decided it was computationally cheaper to align the map with the terrain (as we prefer to do when using GPS).

 

[Academic]

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'.

 

[Pythagorean]

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'.

Not quite. Vision processing is handled largely by the occipital lobe and then integrated into our spatial world model in the parietal lobe.

The motor cortex, and other parts of the brain that handle coordinated output are different (both in terms of location and in terms of information processing).

Some automated muscle movements like reflexes don't even require information from visual input. They're based mostly off mechanoreceptors and the network topology.

 

[Pythagorean]

In other words, "visual processing" is being handed the picture. We then decide what to do with the information the picture provides (along with several other sense inputs) and then we coordinate an output through our muscles.

 

[russ_watters]

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.

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]

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'.

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]

****, I don't do either of those consciously!

 

[DaveC426913]

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?

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]

****, I don't do either of those consciously!

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.

 

[russ_watters]

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.

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.

 

[Monique]

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.

Indeed it does, but it can only "correct" the image up to a certain angle.

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.

On a related note, on many microscopes the vision is mirrored as well (depending on the configuration). It takes some getting used to that moving the controls to the left means the image is moving to the right and that top is down, opposite to what you are used to, but after a 5-10 minutes you get used to operating the controls in the new way.

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.

That is really interesting.

 

[Pythagorean]

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.

I've actually directly experienced something similar to this. I had surgery to fix a wandering eye three times. The first time, the fix didn't stick (I grew out of it, maybe?) the second time, they over-corrected and gave me a cross-eyed look. Finally, the third time (on them) they imbedded an intricate string system, and the next morning, ripped the eye patch off and proceeded to adjust my eye by pulling the strings. It didn't really hurt, but it was certainly uncomfortable. This final go fixed the eye, but:

Because of the lack of use of my right eye, while it was wondering, it didn't develop quite as strongly as my left, dominant eye. It's very strenuous to try to read words with only my right eye. The words are jumbled, as if vertical strips of information were missing (but there's no gap, the remaining vertical strips are joined together so that words run into each other. If I strain really hard, I can straighten it out and read sentences carefully one word at a time, but it "hurts my brain" a lot like three hours of Calc II would hurt your brain.

On a side note, I don't seem to have a problem with depth perception, but I'm not sure how to test the depth perception that is handled by having two sensors. I know we use shading assumptions for depth perception too, which would work regardless of how many eyes you have (barring 0). Anyway, I can tell that I use my eyes in harmony now, it's just that something about the processing for my right eye never developed fully (so says my eye doc).

 

[madness]

I'm finding some of the replies in this thread very interesting. I like Pythagorean's idea that it reduces neural computation, and Russ's point that it seems to shift when we lie sideways is interesting. I'm sure this whole problem is related to proprioception, which i think would need to be reversed if we didn't perceive the image is inverted - this might explain why the amount of neural computation would increase.

 

[Monique]

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.

Here is an interesting review article: http://www.ncbi.nlm.nih.gov/pubmed/17964249"

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.

 

[DaveC426913]

I like Pythagorean's idea that it reduces neural computation...

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.

Our visual wiring may be less a matter of efficiency and more a matter of "that's what we started with".

 

[Pythagorean]

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.

The idea is that the adaptation you mention serves to reduce surprise to the organism, which reduces neural computation by reducing information entropy.

 

[DaveC426913]

The idea is that the adaptation you mention serves to reduce surprise to the organism, which reduces neural computation by reducing information entropy.

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?

 

[Pythagorean]

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?

Not at all. We're talking about why there's a preference. The evolutionary development is a different discussion.