<p><strong>Short answer</strong><br>
Based on the papers I've found I conclude that visual perceptions are not grossly altered after wearing prism glasses for extended periods. Instead, adaptation to prism glasses is mainly brought about by the adjustment of motor behavior to compensate for the shifted visual input. </p>

<p><strong>Background</strong><br>
In a review on the topic of adaptation effects in response to wearing prism glasses, Harris concludes that it is the 'position sense' that adapts, and not the visual system <a href="https://www.researchgate.net/publication/17847340_Perceptual_adaptation_to_inverted_reversed_and_displaced_vision" rel="noreferrer">(Harris, 1965)</a>. In the more recent literature the adaptation to the shifts, or reversals in vision brought about by prism glasses is indeed ascribed to the adaptation of the proprioceptive system, i.e., subjects adapt their motor behavior to compensate for the visual field shift (e.g., <a href="http://link.springer.com/article/10.1007/s00221-002-1097-6" rel="noreferrer">Richter <em>et al</em>. (2002)</a>, <a href="http://link.springer.com/article/10.1007/s00221-005-0159-y" rel="noreferrer">Hatada &amp; Rosetti (2006)</a>), or through shifts in their egocentric reference frame although subtle, short-lasting after-effects do seem to occur in the visual domain too <a href="http://link.springer.com/article/10.1007/s00221-006-0381-2" rel="noreferrer">(Hatada <em>et al</em>., 2006)</a>. 
Note that the experiments described above, human subjects were used and due to practical and ethical reasons, subjects did not wear the prism glasses longer than a few hours up to 1 week at max.</p>

<p>In animal studies, much longer prism-wearing times have been applied. In a study where monkeys wore left-right shifting prism goggles for 90 days, the ipsilateral visual cortex was found to be activated <a href="https://www.ncbi.nlm.nih.gov/pubmed/8606770" rel="noreferrer">(Sugita <em>et al</em>., 1996)</a>. Normally, only the contralateral cortex is activated by ipsilateral stimuli.  Hence, here in these experiments a definite neurophysiological correlate of visual adaptation was found. In four human subjects that wore similar goggles for about 36 days it was subsequently shown that also their ipsilateral cortices were activated, but only after 1 to 2 weeks <a href="https://pdfs.semanticscholar.org/ef47/04066c958c74bfd1e7344d36fe7966dd16ec.pdf" rel="noreferrer">(Miyauchi <em>et al</em>., 2004)</a>. However, the authors of this study don't report the after-effects, but they do conclude that:</p>

<blockquote>
  <p>[The] changes observed [in] adaptation to left–right reversing may be associated with the process of [...] strategic <strong>perceptual-motor control</strong>. One of the most crucial actions for a subject with left–right reversed vision is controlling the hands [...]. For example, when the subjects wearing left–right reversing goggles pick up an object located in the left visual field, they have to use their right hand which is normally located in the right visual field and whose visual information is normally projected to left V1 (ipsilateral to the visual field in which the object appears). To perform such actions, the subjects [...] must change their <strong>strategic (top-down) perceptual-motor control</strong>. It is well-known that top-down visual imagery alone can activate primary visual cortex with a topographical representation [...]. In addition, there are several pieces of evidence which suggest that tactile and proprioceptive perception involve visual imagery and activate visual cortices [...] </p>
</blockquote>

<p>Hence, even when neural adaptation occurs in the visual cortex, it is mainly motor, tactile and proprioceptive adaptations playing a role in adjusting to visual shifts and not so much gross changes in the visual field of view.            </p>

<p><sub><strong>References</strong><br>
<strong>-</strong> <a href="https://www.researchgate.net/publication/17847340_Perceptual_adaptation_to_inverted_reversed_and_displaced_vision" rel="noreferrer">Harris, <em>Psychological Review</em> (1965); <strong>72</strong>(6): 419-44</a><br>
<strong>-</strong> <a href="http://link.springer.com/article/10.1007/s00221-006-0381-2" rel="noreferrer">Hatada <em>et al</em>., <em>Exp Brain Res</em> (2006); <strong>173</strong>(3): 415–24</a><br>
<strong>-</strong> <a href="http://link.springer.com/article/10.1007/s00221-006-0437-3" rel="noreferrer">Hatada <em>et al</em>., <em>Exp Brain Res</em> (2006); <strong>174</strong>(1): 189–98</a><br>
<strong>-</strong> <a href="http://link.springer.com/article/10.1007/s00221-005-0159-y" rel="noreferrer">Hatada &amp; Rosetti, <em>Exp Brain Res</em> (2006); <strong>169</strong>(3): 417–26</a><br>
<strong>-</strong> <a href="https://pdfs.semanticscholar.org/ef47/04066c958c74bfd1e7344d36fe7966dd16ec.pdf" rel="noreferrer">Miyauchi <em>et al</em>., <em>J Physiol - Paris</em> (2004); <strong>98</strong>: 207–19</a><br>
<strong>-</strong> <a href="http://link.springer.com/article/10.1007/s00221-002-1097-6" rel="noreferrer">Richter <em>et al</em>., <em>Exp Brain Res</em> (2002); <strong>144</strong>(4): 445–57</a><br>
<strong>-</strong> <a href="https://www.ncbi.nlm.nih.gov/pubmed/8606770" rel="noreferrer">Sugita <em>et al</em>., <em>Nature</em> (1996); <strong>380</strong>: 523–6</a></sub>   </p>

CC BY-SA 3.0
2017-01-11T22:51:19.090Z
I don't see references to experiments where people wear upside down glasses. And I find it hard to understand that the visual system doesn't adapt and makes us see the world normal again. It's essentially the same as my visual system adapting to the upside-down projection on the retina. Or are my motor functions "turned" 180 degrees with the result I see everything normal again? And is the same thing the case in the 180 degrees rotation of the upside-down projection on our retina(s)? How is the upside-down image on the retina is represented in the visual system?Two times upside-down is normal.
Deschele Schilder
CC BY-SA 3.0
2017-01-11T23:04:01.377Z
@descheleschilder - Essentially left-right prism glasses are a more extreme example of yours, so it covers the topic nicely. And the visual system does adapt, as shown above, but not by turning the entire image upside down. Motor functions are adapted, as described above. And the 2x upside down note I quite frankly don't understand. I'm just giving you the evidence.If you can find me references that tell us the visual system adapts by inverting retinal images - be my guest!
AliceD
CC BY-SA 3.0
2017-01-12T11:20:07.233Z
I think the upside-down image on the retina isn't turned 180 degrees by the visual system. The system gets the image and I can't see how it's turned upside-down again. Instead, our relations to the image are rotated 180 degrees, which is actually the same as rotating the image.To examine if a projection of a highly asymmetrical (with respect to up and down) object is turned around again by the visual system you can look at the system to see if the object is still upside-down represented or not.
Deschele Schilder
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2017-01-12T11:30:12.520Z
@descheleschilder - Your latter comment contradicts your question. Quite frankly I don't understand what you are after
AliceD
CC BY-SA 3.0
2017-01-12T13:52:53.027Z
When you start wearing upside-down glasses, then you see the world upside-down. After a while, you'll see the world normal again. How perceives a person wearing these glasses the transition from upside-down to normal again? Is it a sudden flip over, a gradually one, or one that happens during sleep, after gathering information in the waking state? Without glasses, our visual system receives un upside-down image as input, and our orientation is adjusted so we see the world normal. So the same happens if the image send to the visual system is 180 degrees rotated. But how is the transition seen?
Deschele Schilder
CC BY-SA 3.0
2017-01-12T13:58:58.837Z
Is it possible to see (with brain scans) to see if an object is represented upside-down If I put the prism glasses on? Ater all one can see the representation of checkerboard in the visual system as somewhat distorted black and white squares.
Deschele Schilder
CC BY-SA 3.0
2017-01-12T14:17:26.853Z
Yes when wearing the glasses the image is flipped for sure
AliceD
CC BY-SA 3.0
2017-01-12T14:53:43.013Z
Of course, it's flipped, but if you can see that on some scan too, you can also see if it stays represented upside-down (I can't imagine the visual system rotating the perceived imaged 180 degrees). If it stays represented upside-down, then the adaptation to see normal again, is attributable to other factors (like you already wrote in your answer). But this still doesn't answer my question how the transition is perceived (seen).
Deschele Schilder
CC BY-SA 3.0
2017-01-12T15:03:49.897Z
It stays flipped see my answer
AliceD
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2017-01-13T05:14:18.483Z
@descheleschilder The brain doesn't flip images from the retina, you are falling prey to a common fallacy known as the Homunculus Argument, or Cartesian Theater (see https://en.wikipedia.org/wiki/Homunculus_argument, and also a discussion here: https://cogsci.stackexchange.com/questions/337/why-would-the-brain-flip-the-images-perceived-by-your-eyes).
Arnon Weinberg
CC BY-SA 3.0
2017-01-13T16:13:49.660Z
@ArnonWeinberg . Ahhhh is that what is causing this confusion? Yes just totally Mr. Schele Schilder -  the brain does not flip the image,  not with or without glasses. The retinal image does however
AliceD
CC BY-SA 3.0
2017-01-13T19:38:43.403Z
@AliceDThe retinal image flips, and so does the image represented in the visual system. Do you think the representation of the world in the visual system stays the same if you flip the retinal image by wearing glasses? Like you wrote yourself (*" it is mainly motor, tactile and proprioceptive adaptations playing a role in adjusting to visual shifts"*), processes surrounding the representation take care of seeing the world normal again after a while. But that still doesn't answer my question: *How* is the transition from upside-down to normal perceived by people wearing upside-down glasses?
Deschele Schilder
CC BY-SA 3.0
2017-01-13T19:43:50.110Z
@AliceD Why does the brain does not flip the image if we are wearing glasses? If that's the case then there's no difference between wearing glasses and not wearing glasses and will we see the same after putting on the upside-down glasses.
Deschele Schilder
CC BY-SA 3.0
2017-01-13T20:12:15.227Z
@ArnonWeinberg I didn't write the brain flips images from the retina. I wrote the brain flips the image *after* you've put on the upside-down glasses, which flips the world, and thus the represented image in the visual system. The glasses give a "normal" representation in the visual system and the brain doesn't adjust itself by rotating this representation again, but by the same processes which occur in adjusting sight to the upside-down images send to the visual system (these images are also represented upside-down, as can be seen by brain scans). But, _how is the transition seen?_
Deschele Schilder
CC BY-SA 3.0
2017-01-13T20:23:57.017Z
To avoid confusion, the brain *doesn't  adjust* itself by rotating the represented image, but it rotates it only after you put the glasses on. After that processes written in the last part of the answer make us see the world normal again. You can ask yourself too if these processes are there at the moment of birth or are developed in some time after birth, but looking at babies I suspect these processes were already developed in the womb, so a newly born sees thing normal. But, *how is the transition in adults, wearing upside-down glasses, seen?*
Deschele Schilder
CC BY-SA 3.0
2017-01-13T20:26:16.807Z
There *is no transition*; please read my answer carefully - this discussion is going nowhere, sorry to say. Your premise needs sources and at this time, despite my comment above - you still assume that the brain adapts by reversing the image (what makes you think it does?) - it *does not*, based on the papers I found.
AliceD
CC BY-SA 3.0
2017-01-16T07:30:26.530Z
I do *not* think the brain adapts by reversing the image after some time. The image in the brain is only rotated right after you put the glasses on. And it stays that way all the time you wearing glasses, just as the flipped image of the world stays there from birth. We perceive it as normal not because the image in the brain is flipped (we see things normal, but the represented image in the brain is rotated 180 degrees), but we adapt our systems surrounding the upside-down image (not wearing glasses). The same happens after a while when you dó wear these glasses.
Deschele Schilder
CC BY-SA 3.0
2017-01-16T07:43:04.860Z
@AliceD So the homunculus argument doesn't apply. I see things as they happen in the brain, and don't think you only perceive the world normal if the image in the brain has the same orientation). I did some research and a female artist in the sixties, wearing upside-down glasses, reported that after a while she saw the world in a flipping state of normal and upside-down, and the normal mode eventually got hold again. After she put off the glasses her world flipped again but was very vast restored to normal again. Much faster then the transition to normal while wearing glasses. The answer!
Deschele Schilder
CC BY-SA 3.0
2017-01-16T07:44:56.460Z
@AliceD So there *is* a transition. Coming directly from human experience! The human brain has great plasticity!
Deschele Schilder
CC BY-SA 3.0
2017-01-16T09:28:50.723Z
@descheleschilder it seems you are seeking a confirmation of an unsupported assumption. Anecdotal evidence is evidence,  yet not convincing. You might, however, consider answering your own question as it may be interesting to others reading your question.
AliceD
CC BY-SA 3.0
2017-01-17T00:09:39.890Z
@AliceDYou're absolutely right! Look here: https://www.theguardian.com/education/2012/nov/12/improbable-research-seeing-upside-down                                                                                                      It's interesting to note that George Stratton said to perceive the world in a normal after wearing the glasses for a while, while in a later experiment the persons who took part in it felt if they were walking upside down, with their feet in the clouds! But that way you see the world normal too, but in (left-right) mirror image, if only up and down are reversed.
Deschele Schilder
CC BY-SA 3.0
2017-01-17T00:34:43.527Z
@AliceDAbout the mirror image I'm not so sure, coming to think about it.The persons would surely have reported that. So left and right are also reversed, if they see the world normal, with their feet in the clouds. Not the image in the brain (that stays upside down because of the glasses, and in that case left and right áre reversed; the eye lens reverses up and down, and left and right, so if you look at the image behind the retina on your head, you see the image normal, while in front of the retina you see left and right flipped; confusing not?), but their relation to it.
Deschele Schilder
CC BY-SA 3.0
2017-01-17T00:59:30.843Z
@AlicedOne last comment. In the fore last comment, I was referring to the wrong article. This is the right one http://io9.gizmodo.com/5905180/does-your-brain-really-have-the-power-to-see-the-world-upside-down The link in the fore last comment shows that the world dóes flip after a while. Man, this stuff makes me flip! I think the best way to see what happens and how you see flipping things, is to wear them glasses myself...
Deschele Schilder
CC BY-SA 3.0
2017-01-17T01:20:57.800Z
@AliceDOne last last comment: Stratton used glasses that flipped up and down ánd left and right (like the eye lens), not just up and down. Maybe that's why persons feel like they walking with their feet in the clouds.
Deschele Schilder
CC BY-SA 3.0
2017-01-11T20:06:47.347Z
2017-01-11T20:26:30.390Z
2017-01-11T20:26:30.390Z
AliceD
<p>If someone wears prism glasses that turn the visual field upside down (see <a href="https://www.bing.com/videos/search?q=upside%20down%20glasses&amp;view=detail&amp;mid=645B90783B432E785CDE645B90783B432E785CDE&amp;FORM=VIRE" rel="nofollow noreferrer">this</a> video), this person will eventually adapt and see the world in its normal orientation again. Now my question is, how does the person wearing these glasses perceive the transition from upside-down back to normal after the prism glasses are taken off?</p>

<perception><vision><adaptation>
How does a person who wears prism glasses through which the world is perceived upside-down experience the transition back to normal?
Deschele Schilder
# How does a person who wears prism glasses through which the world is perceived upside-down experience the transition back to normal?

(Asked by: username_0 on 2016-12-23)

If someone wears prism glasses that turn the visual field upside down (see [this](https://www.bing.com/videos/search?q=upside%20down%20glasses&view=detail&mid=645B90783B432E785CDE645B90783B432E785CDE&FORM=VIRE) video), this person will eventually adapt and see the world in its normal orientation again. Now my question is, how does the person wearing these glasses perceive the transition from upside-down back to normal after the prism glasses are taken off?

**Tags:** perception, vision, adaptation


---

## 1 answers

### Answer by username_1 on 2017-01-11. Score: 5 | Accepted answer

**Short answer**  
Based on the papers I've found I conclude that visual perceptions are not grossly altered after wearing prism glasses for extended periods. Instead, adaptation to prism glasses is mainly brought about by the adjustment of motor behavior to compensate for the shifted visual input.

**Background**  
In a review on the topic of adaptation effects in response to wearing prism glasses, Harris concludes that it is the 'position sense' that adapts, and not the visual system [(Harris, 1965)](https://www.researchgate.net/publication/17847340_Perceptual_adaptation_to_inverted_reversed_and_displaced_vision). In the more recent literature the adaptation to the shifts, or reversals in vision brought about by prism glasses is indeed ascribed to the adaptation of the proprioceptive system, i.e., subjects adapt their motor behavior to compensate for the visual field shift (e.g., [Richter *et al*. (2002)](http://link.springer.com/article/10.1007/s00221-002-1097-6), [Hatada & Rosetti (2006)](http://link.springer.com/article/10.1007/s00221-005-0159-y)), or through shifts in their egocentric reference frame although subtle, short-lasting after-effects do seem to occur in the visual domain too [(Hatada *et al*., 2006)](http://link.springer.com/article/10.1007/s00221-006-0381-2).
Note that the experiments described above, human subjects were used and due to practical and ethical reasons, subjects did not wear the prism glasses longer than a few hours up to 1 week at max.

In animal studies, much longer prism-wearing times have been applied. In a study where monkeys wore left-right shifting prism goggles for 90 days, the ipsilateral visual cortex was found to be activated [(Sugita *et al*., 1996)](https://www.ncbi.nlm.nih.gov/pubmed/8606770). Normally, only the contralateral cortex is activated by ipsilateral stimuli. Hence, here in these experiments a definite neurophysiological correlate of visual adaptation was found. In four human subjects that wore similar goggles for about 36 days it was subsequently shown that also their ipsilateral cortices were activated, but only after 1 to 2 weeks [(Miyauchi *et al*., 2004)](https://pdfs.semanticscholar.org/ef47/04066c958c74bfd1e7344d36fe7966dd16ec.pdf). However, the authors of this study don't report the after-effects, but they do conclude that:

> [The] changes observed [in] adaptation to left–right reversing may be associated with the process of [...] strategic **perceptual-motor control**. One of the most crucial actions for a subject with left–right reversed vision is controlling the hands [...]. For example, when the subjects wearing left–right reversing goggles pick up an object located in the left visual field, they have to use their right hand which is normally located in the right visual field and whose visual information is normally projected to left V1 (ipsilateral to the visual field in which the object appears). To perform such actions, the subjects [...] must change their **strategic (top-down) perceptual-motor control**. It is well-known that top-down visual imagery alone can activate primary visual cortex with a topographical representation [...]. In addition, there are several pieces of evidence which suggest that tactile and proprioceptive perception involve visual imagery and activate visual cortices [...]

Hence, even when neural adaptation occurs in the visual cortex, it is mainly motor, tactile and proprioceptive adaptations playing a role in adjusting to visual shifts and not so much gross changes in the visual field of view.

**References**  
**-** [Harris, *Psychological Review* (1965); **72**(6): 419-44](https://www.researchgate.net/publication/17847340_Perceptual_adaptation_to_inverted_reversed_and_displaced_vision)  
**-** [Hatada *et al*., *Exp Brain Res* (2006); **173**(3): 415–24](http://link.springer.com/article/10.1007/s00221-006-0381-2)  
**-** [Hatada *et al*., *Exp Brain Res* (2006); **174**(1): 189–98](http://link.springer.com/article/10.1007/s00221-006-0437-3)  
**-** [Hatada & Rosetti, *Exp Brain Res* (2006); **169**(3): 417–26](http://link.springer.com/article/10.1007/s00221-005-0159-y)  
**-** [Miyauchi *et al*., *J Physiol - Paris* (2004); **98**: 207–19](https://pdfs.semanticscholar.org/ef47/04066c958c74bfd1e7344d36fe7966dd16ec.pdf)  
**-** [Richter *et al*., *Exp Brain Res* (2002); **144**(4): 445–57](http://link.springer.com/article/10.1007/s00221-002-1097-6)  
**-** [Sugita *et al*., *Nature* (1996); **380**: 523–6](https://www.ncbi.nlm.nih.gov/pubmed/8606770)

> **Comments:**
> **username_0**: I don't see references to experiments where people wear upside down glasses. And I find it hard to understand that the visual system doesn't adapt and makes us see the world normal again. It's essentially the same as my visual system adapting to the upside-down projection on the retina. Or are my motor functions "turned" 180 degrees with the result I see everything normal again? And is the same thing the case in the 180 degrees rotation of the upside-down projection on our retina(s)? How is the upside-down image on the retina is represented in the visual system?Two times upside-down is normal.  
> **username_1**: @descheleschilder - Essentially left-right prism glasses are a more extreme example of yours, so it covers the topic nicely. And the visual system does adapt, as shown above, but not by turning the entire image upside down. Motor functions are adapted, as described above. And the 2x upside down note I quite frankly don't understand. I'm just giving you the evidence.If you can find me references that tell us the visual system adapts by inverting retinal images - be my guest!  
> **username_0**: I think the upside-down image on the retina isn't turned 180 degrees by the visual system. The system gets the image and I can't see how it's turned upside-down again. Instead, our relations to the image are rotated 180 degrees, which is actually the same as rotating the image.To examine if a projection of a highly asymmetrical (with respect to up and down) object is turned around again by the visual system you can look at the system to see if the object is still upside-down represented or not.  
> **username_1**: @descheleschilder - Your latter comment contradicts your question. Quite frankly I don't understand what you are after  
> **username_0**: When you start wearing upside-down glasses, then you see the world upside-down. After a while, you'll see the world normal again. How perceives a person wearing these glasses the transition from upside-down to normal again? Is it a sudden flip over, a gradually one, or one that happens during sleep, after gathering information in the waking state? Without glasses, our visual system receives un upside-down image as input, and our orientation is adjusted so we see the world normal. So the same happens if the image send to the visual system is 180 degrees rotated. But how is the transition seen?  
> **username_0**: Is it possible to see (with brain scans) to see if an object is represented upside-down If I put the prism glasses on? Ater all one can see the representation of checkerboard in the visual system as somewhat distorted black and white squares.  
> **username_1**: Yes when wearing the glasses the image is flipped for sure  
> **username_0**: Of course, it's flipped, but if you can see that on some scan too, you can also see if it stays represented upside-down (I can't imagine the visual system rotating the perceived imaged 180 degrees). If it stays represented upside-down, then the adaptation to see normal again, is attributable to other factors (like you already wrote in your answer). But this still doesn't answer my question how the transition is perceived (seen).  
> **username_1**: It stays flipped see my answer  
> **username_2**: @descheleschilder The brain doesn't flip images from the retina, you are falling prey to a common fallacy known as the Homunculus Argument, or Cartesian Theater (see https://en.wikipedia.org/wiki/Homunculus_argument, and also a discussion here: https://cogsci.stackexchange.com/questions/337/why-would-the-brain-flip-the-images-perceived-by-your-eyes).  
> **username_1**: @ArnonWeinberg . Ahhhh is that what is causing this confusion? Yes just totally Mr. Schele Schilder -  the brain does not flip the image,  not with or without glasses. The retinal image does however  
> **username_0**: @username_1The retinal image flips, and so does the image represented in the visual system. Do you think the representation of the world in the visual system stays the same if you flip the retinal image by wearing glasses? Like you wrote yourself (*" it is mainly motor, tactile and proprioceptive adaptations playing a role in adjusting to visual shifts"*), processes surrounding the representation take care of seeing the world normal again after a while. But that still doesn't answer my question: *How* is the transition from upside-down to normal perceived by people wearing upside-down glasses?  
> **username_0**: @username_1 Why does the brain does not flip the image if we are wearing glasses? If that's the case then there's no difference between wearing glasses and not wearing glasses and will we see the same after putting on the upside-down glasses.  
> **username_0**: @ArnonWeinberg I didn't write the brain flips images from the retina. I wrote the brain flips the image *after* you've put on the upside-down glasses, which flips the world, and thus the represented image in the visual system. The glasses give a "normal" representation in the visual system and the brain doesn't adjust itself by rotating this representation again, but by the same processes which occur in adjusting sight to the upside-down images send to the visual system (these images are also represented upside-down, as can be seen by brain scans). But, _how is the transition seen?_  
> **username_0**: To avoid confusion, the brain *doesn't  adjust* itself by rotating the represented image, but it rotates it only after you put the glasses on. After that processes written in the last part of the answer make us see the world normal again. You can ask yourself too if these processes are there at the moment of birth or are developed in some time after birth, but looking at babies I suspect these processes were already developed in the womb, so a newly born sees thing normal. But, *how is the transition in adults, wearing upside-down glasses, seen?*  
> **username_1**: There *is no transition*; please read my answer carefully - this discussion is going nowhere, sorry to say. Your premise needs sources and at this time, despite my comment above - you still assume that the brain adapts by reversing the image (what makes you think it does?) - it *does not*, based on the papers I found.  
> **username_0**: I do *not* think the brain adapts by reversing the image after some time. The image in the brain is only rotated right after you put the glasses on. And it stays that way all the time you wearing glasses, just as the flipped image of the world stays there from birth. We perceive it as normal not because the image in the brain is flipped (we see things normal, but the represented image in the brain is rotated 180 degrees), but we adapt our systems surrounding the upside-down image (not wearing glasses). The same happens after a while when you dó wear these glasses.  
> **username_0**: @username_1 So the homunculus argument doesn't apply. I see things as they happen in the brain, and don't think you only perceive the world normal if the image in the brain has the same orientation). I did some research and a female artist in the sixties, wearing upside-down glasses, reported that after a while she saw the world in a flipping state of normal and upside-down, and the normal mode eventually got hold again. After she put off the glasses her world flipped again but was very vast restored to normal again. Much faster then the transition to normal while wearing glasses. The answer!  
> **username_0**: @username_1 So there *is* a transition. Coming directly from human experience! The human brain has great plasticity!  
> **username_1**: @descheleschilder it seems you are seeking a confirmation of an unsupported assumption. Anecdotal evidence is evidence,  yet not convincing. You might, however, consider answering your own question as it may be interesting to others reading your question.  
> **username_0**: @username_1You're absolutely right! Look here: https://www.theguardian.com/education/2012/nov/12/improbable-research-seeing-upside-down                                                                                                      It's interesting to note that George Stratton said to perceive the world in a normal after wearing the glasses for a while, while in a later experiment the persons who took part in it felt if they were walking upside down, with their feet in the clouds! But that way you see the world normal too, but in (left-right) mirror image, if only up and down are reversed.  
> **username_0**: @username_1About the mirror image I'm not so sure, coming to think about it.The persons would surely have reported that. So left and right are also reversed, if they see the world normal, with their feet in the clouds. Not the image in the brain (that stays upside down because of the glasses, and in that case left and right áre reversed; the eye lens reverses up and down, and left and right, so if you look at the image behind the retina on your head, you see the image normal, while in front of the retina you see left and right flipped; confusing not?), but their relation to it.  
> **username_0**: @AlicedOne last comment. In the fore last comment, I was referring to the wrong article. This is the right one http://io9.gizmodo.com/5905180/does-your-brain-really-have-the-power-to-see-the-world-upside-down The link in the fore last comment shows that the world dóes flip after a while. Man, this stuff makes me flip! I think the best way to see what happens and how you see flipping things, is to wear them glasses myself...  
> **username_0**: @username_1One last last comment: Stratton used glasses that flipped up and down ánd left and right (like the eye lens), not just up and down. Maybe that's why persons feel like they walking with their feet in the clouds.  

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