Understanding Vision Inversion: The Myth and Meaning Behind It

[madness]

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?

 

[Evo]

This has nothing to do with philosophy.

 

[madness]

Well since it is a question about subjective experience it kindof does...

 

[Evo]

Well since it is a question about subjective experience it kindof does...

Not for our rules.

 

[jtbell]

what does it mean when people say your brain inverts your vision from your eye?

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."

 

[lisab]

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."

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...

 

[Evo]

I believe this is the study madness is referring to.

The myth of upright vision. A psychophysical and functional
imaging study of adaptation to inverting spectacles

Abstract. The adaptation to inverting prisms and mirror spectacles was studied in four subjects over periods of six to ten days. Subjects showed rapid adaptation of visuomotor functions, but did not report return of upright vision. The persistence of the transformed visual image was confirmed by the subjects' perception of shape from shading. No alteration of the retinotopy of early visual cortical areas was seen in the functional magnetic resonance images. These results are discussed in the context of previous claims of upright vision with inverting prisms and mirror spectacles.

http://wexler.free.fr/library/files...udy of adaptation to inverting spectacles.pdf

 

[Antiphon]

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.

 

[zoobyshoe]

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.

It should be sufficient to debunk it because the original and supporting claims all said six/seven days:

Stratton's (1897) claim that he saw the world in its canonical orientation on the sixth day with inverting prisms was followed by attempts to reproduce his findings in 1928 and 1952 (see Kottenhoff 1961; Gregory 1998b). A number of studies at Innsbruck University with upside-down inverting mirrors (Kohler 1964) also resulted in reports of upright vision after one week.

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.

 

[atyy]

but is this just relative to our auditory and proprioceptive cues?

http://wexler.free.fr/library/files...udy of adaptation to inverting spectacles.pdf

"But no subject claimed that he had regained upright vision or that his visual image matched his body sense"

 

[russ_watters]

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...

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.

 

[zoobyshoe]

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.

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.

 

[Ryan_m_b]

There's no objective up or down.

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.

 

[Ryan_m_b]

What does it even mean for your vision to flip

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.

and what does it mean when people say your brain inverts your vision from your eye?

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 perceived at the bottom.

Inverts it relative to what?

Relative to your body. The images your brain perceives is inverted to the image your eye senses.

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.

See my first comment replying to zoobyshoe.

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?

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.

 

[madness]

"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 perceived 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.

 

[madness]

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.

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.

 

[zoobyshoe]

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

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.

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.

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.

 

[zoobyshoe]

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.

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:

Cortical maps are arranged into clusters in which several maps have parallel eccentricity representations, while the angular representations within a cluster alternate in visual field sign.

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.

 

[madness]

"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.

 

[zoobyshoe]

I googled and found there are cases of pathological inversion of vision:

INVERTED OR TILTED PERCEPTION DISORDER
Summary. Aim. In the context of the increasing number of reported cases of patients presenting tilt or reversal of vision anomaly (here reviewed), we call the attention to the work of Justo Gonzalo (1910-1986), scarcely known in the contemporary literature. His work deals with that anomaly, and with tactile and auditory inversion, in relation to what he called central and paracentral syndromes, interpreted from the functional model he developed. Development. Gonzalo makes reference to 25 patients with chronic tilted vision, some of them with almost inverted perception in visual, tactile and auditory systems, under minimum stimulus. The central syndrome is caused by unilateral lesion in the parieto-occipital cortex, equidistant from the visual, tactile and auditory projection areas, and is characterized by bilateral multisensory involvement, and by dynamic effects following physiological laws of nervous excitability. Thus, as the illumination of an object was diminishing, it was perceived progressively tilted, reduced, and losing form and colors, following a physiological order; however the image was corrected by increasing the illumination, or by facilitation through other sensory stimulus. The central syndrome is compared with the reviewed cases. Conclusions. This syndrome involves a deficit of nervous excitability which would induce an integration deficit, tilted vision emerging as a more common affection than believed. The central syndrome reveals aspects of the cerebral dynamics, suggesting a functional continuity and unity of the cortex. This is reflected in the model that was proposed, based on functional gradations through the cortex and scaling laws of dynamic systems.

http://www.neurologia.com/pdf/Web/4403/x030157en.pdf

Inverted vision after frontal lobe disease.
Solms M, Kaplan-Solms K, Saling M, Miller P.
Source
Division of Neurosurgery, University of the Witwatersrand, Johannesburg.
Abstract
A case of bifrontal abscesses is reported. The patient claimed that he sometimes saw the world as if it were upside-down. A review of the literature reveals that, since 1805, 21 similar cases have been documented. The present case is unusual in that the neuropsychological status of the patient is investigated in some detail, and in that it seems to be the first report of inverted vision in a case of frontal lobe disease.

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.

 

[madness]

I googled and found there are cases of pathological inversion of vision:



http://www.neurologia.com/pdf/Web/4403/x030157en.pdf


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.

Sounds very interesting. I'll try to read these later on. At the moment, I'm still convinced that topographic maps (and hence our perception), are only oriented relative to each other through the pattern of connections between them. It is perfectly possible for my visual perception to be disoriented with respect to my proprioceptic of auditory perception, but I don't believe it can be oriented relative to my retina or the world itself.

 

[madness]

From your paper on inversion

It is also proposed a [sic] disfunction of the multisensory parieto-insular vestibular cortex, or its afferences, or of its association cortical areas [21,35], or a disorder of visiospatial integration [25,29,42].

I believe this supports my argument. (Note vestibular = balance).

 

[zoobyshoe]

Sounds very interesting. I'll try to read these later on. At the moment, I'm still convinced that topographic maps (and hence our perception), are only oriented relative to each other through the pattern of connections between them. It is perfectly possible for my visual perception to be disoriented with respect to my proprioceptic of auditory perception, but I don't believe it can be oriented relative to my retina or the world itself.

Oliver Sacks asserts:

"The retina, like the cochlea, is mapped systematically on the cerebral cortex, and damage to it (or edema beneath it) can cause strange distortions of vision, sometimes a warping of horizontal and vertical lines, as if one is looking through a fish eye lens. These distortions may be very noticeable if one glances at individual objects: a rectangular picture frame may appear both curved and trapezoidal, or a cup or saucer bizarrely deformed."
Musicophilia, p.145n

The question in all this is how we are conscious of any given perception. Does consciousness of what image is falling on your retina take place at the cortical retinal map? No one knows.

At any rate, we can, by pathological mechanisms, become conscious of a visual field that is inverted, or otherwise grossly distorted, with respect to what we're used to.

 

[madness]

"The question in all this is how we are conscious of any given perception. Does consciousness of what image is falling on your retina take place at the cortical retinal map? No one knows."

The evidence is that early topographic maps are not sufficient for consciousness. The topographic organisation of other regions becomes harder and harder to establish towards the frontal cortex.

http://www.ncbi.nlm.nih.gov/pubmed/17395576

Empirical evidence to date suggests that no single brain area is both necessary and sufficient for consciousness. Instead, necessary and sufficient conditions appear to involve both activation of a distributed representation of the visual scene in primary visual cortex and ventral visual areas, plus parietal and frontal activity.

 

[zoobyshoe]

"The question in all this is how we are conscious of any given perception. Does consciousness of what image is falling on your retina take place at the cortical retinal map? No one knows."

The evidence is that early topographic maps are not sufficient for consciousness. The topographic organisation of other regions becomes harder and harder to establish towards the frontal cortex.

http://www.ncbi.nlm.nih.gov/pubmed/17395576

Empirical evidence to date suggests that no single brain area is both necessary and sufficient for consciousness. Instead, necessary and sufficient conditions appear to involve both activation of a distributed representation of the visual scene in primary visual cortex and ventral visual areas, plus parietal and frontal activity.

I know. What I'm saying is that the location of the activity that results in consciousness might be cortical, it might be in the thalamus, or it might be distributed. A television is necessary to, but not sufficient for, a television image. One also needs electricity and a TV signal. The location of the television image, however, is on the screen.

 

[madness]

Electrical stimulation of the parietal cortex (which is further down the processing stream than the primary visual cortex) causes the experience of phosphenes. This seems to be evidence that conscious experience does not take place in the topographic map of the primary visual cortex.

I believe that consciousness arises from the integrated activity of various brain structures. This integration can be achieved through thalamocortical loops, phase synchronisation between brain structures etc. In fact the only fundamental scientific theory of consciousness that is genuinely considered at the moment is based on this kind of integration (http://www.biomedcentral.com/1471-2202/5/42/).

 

[zoobyshoe]

Electrical stimulation of the parietal cortex (which is further down the processing stream than the primary visual cortex) causes the experience of phosphenes. This seems to be evidence that conscious experience does not take place in the topographic map of the primary visual cortex.

I believe that consciousness arises from the integrated activity of various brain structures. This integration can be achieved through thalamocortical loops, phase synchronisation between brain structures etc. In fact the only fundamental scientific theory of consciousness that is genuinely considered at the moment is based on this kind of integration (http://www.biomedcentral.com/1471-2202/5/42/).

I agree with all this. No piece of cortex is sufficient for consciousness. I wasn't suggesting that. I was suggesting that consciousness might happen at the cortex, just as the television image happens at the screen, despite the fact a TV screen by itself is not sufficient for a TV image.

The reason I suggested that was in reaction to Sacks report about physical distortion of the cortex (as by a hematoma) causing a corresponding distortion of the perceived image. It was an incidental remark and I didn't intend to get off the subject of image inversion with it.

The point of my post was:
"At any rate, we can, by pathological mechanisms, become conscious of a visual field that is inverted, or otherwise grossly distorted, with respect to what we're used to."

Your point, that no one has explained what it might mean for the image to be inverted, is a good one. I can't explain what it would mean, here, nor pinpoint a necessity for it. All I can offer is the fact it does seem to undergo an inversion, an inversion that can be subtracted by pathological means.

 

[Antiphon]

I might be missing something but I thought the point of the research was whether this inversion mapping if it exists could be remapped in short order (days) by the brain.

The real experiment (like learning a language accent-free) is whether the brain makes this mapping in a young state and freezes it or loses the capability to change it later. Which makes a lot of sense to me.

Massive ethical problems aside, someone needs to put the inverting glasses on some toddlers and infants and see what happens.

 

[zoobyshoe]

I might be missing something but I thought the point of the research was whether this inversion mapping if it exists could be remapped in short order (days) by the brain.

The thing to understand is that there are no maps of the external world in the brain. The map in question here would be the map of the retina on the brain. There's also some kind of vestibular map, and some kind of proprioceptive map involved in the perception of Up and Down. As Madness points out the important thing is for these to be coordinated with each other. They are: if you stand on your head, or hang upside down from a tree limb, all these senses are in agreement that you're upside down. The information they receive from the external world and interior body position and fluid pressure sensors will all agree that this is the reverse state of the conventional one.

Massive ethical problems aside, someone needs to put the inverting glasses on some toddlers and infants and see what happens.

I think if you look into the paper Evo linked to you'll see that they've done things like this with animals and it simply seems to damage their ability to ever process the information correctly. I think they concluded that separating vision out from the other participating senses and feeding it contradictory input in developing animals just caused a sort of atrophy of vision.

 

[madness]

I agree with all this. No piece of cortex is sufficient for consciousness. I wasn't suggesting that. I was suggesting that consciousness might happen at the cortex, just as the television image happens at the screen, despite the fact a TV screen by itself is not sufficient for a TV image.

The reason I suggested that was in reaction to Sacks report about physical distortion of the cortex (as by a hematoma) causing a corresponding distortion of the perceived image. It was an incidental remark and I didn't intend to get off the subject of image inversion with it.

The point of my post was:
"At any rate, we can, by pathological mechanisms, become conscious of a visual field that is inverted, or otherwise grossly distorted, with respect to what we're used to."

Your point, that no one has explained what it might mean for the image to be inverted, is a good one. I can't explain what it would mean, here, nor pinpoint a necessity for it. All I can offer is the fact it does seem to undergo an inversion, an inversion that can be subtracted by pathological means.

My point is that the image is inverted with respect to other internal maps rather than the external world. We have retinotopic and spatiotopic maps; vestibular, somatosensory and auditory cues etc. We seem to build up several internal representations of space which are integrated in a way which we do not understand. It seems to me that any pathological mechanisms causing an inverted or distorted sense of vision are due to the interaction between these various representations of space rather than due to the relationship between the internal representation and the external world.