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

zomgwtf

I think it would still work... the only reason it seems to us that the images on our retina are inverted is because our brain has adjusted to seeing things 'upright' because they are normal relative to our natural perception.

russ_watters

Try this: hold your hands out in front of you, palm toward you, fingers pointed up. Notice that your pinkies are next to each other. Now rotate your hands 180 degrees so both are facing down. Notice that your thumbs are now next to each other. If your brain overlaid the pictures on top of each other without re-arranging them either by switching their left/right positions or by rotating the image of each eye, they wouldn't line up.

Btw, you didn't respond to this: I want to make sure we are at least understanding the other's point: do you agree that your brain does rotate images?

zomgwtf

Hmmm I am pretty sure that 'uprightness' is a function of the brain after all perception is completed. I might be wrong here though.

What this means though, if I'm right, is that your brain has already overlayed the images correctly and they are already lined up, albeit inversed to how you think you are seeing things. That's my entire point though, if the brain didn't switch things to 'see upright as normal' you would still perceive things as normal, as long as you didn't effect your vision. So if we lost this ability to adjust to perceptions then when we put on those glasses Monique spoke of we would no longer be able to see things as upright anymore, they would permanently look inversed to us and we would have to conciously learn how to function with such vision. This 'correction factor' you talk about does that automatically for us...

I think you've mentioned this already a few posts back I just don't agree with it increases efficiency in a normal perceptive state. Things would just look normal all the time...

EDIT: didn't see the last prat of your post. I do agree with what you call a correction but I disagree that it is a 'correction' in that there is an objective orientation to the world. It is a correction in the sense that thinking upright is easier for you at all times. But under normal circumstances (without technology to invert our vision) this wouldn't be very useful... things would always still appear normal... unless you held your head in an awkward position for an extended period of time..

For instance: If you put on those glasses which invert the image you see prior to it entering your retina and then your brain adjusts to seeing it as 'normal' does that mean that what you are seeing now is the 'real' normal? No, your brain still just adjusted to the new orientations relative to yourself, and it'll do this for all situations. Without which we would still see things as 'normal' and upright we just wuoldn't be able to adjust to different perspective orientations sub-conciously.

russ_watters

You didn't respond to the thought experiment: they can't be lined up if they are inverted.

If you built a model of your eye and looked at what was projected on it, you'd see this: [attached]

If your brain didn't reorient the images either by switching the left and right images or by rotating both, they wouldn't be overlaid properly.

Attached Thumbnails

 

zomgwtf

No what I'm saying is that the overlaying and those adjustments occurs prior to 'upright' adjustment factors. If what you were sayin were true then when you wore the inversion glasses that should be what you see, but it isn't because your brain already pieces the image together prior to everything being adjusted to "upright".

Also that's just what is seen in the retina prior to brain processing the information. Uprightness and overlay/depth perception are different processes. If we didn't have the ability to adjust for 'uprightness' we would still process the image overlay etc. That was what I was trying to say earlier .

russ_watters

Ok, thats what I thought. You agree that the brain is doing some processing work here, but you think it is unnecessary: you think that if the brain didn't do that processing work, we'd have learned a different "normal" and we'd never know the difference.

In that case, you are arguing that the brain evolved a function that it doesn't need. Why would it do that?

russ_watters

What are "inversion glasses"?
So you're sying this happens:?

1. Image hits retina oriented as in the picture I showed.
2. Brain corrects the left/right orientation of the images.
3. Brain stiches the images together.
4. Brain rotates the entire image upright.

Now you've added two steps that I thought you were saying were unnecessary. Why doesn't the brain just do this:

1. Image hits the retina.
2. Brain stiches the images together like the picture I showed.

Or:

1. Image hits the retina.
2. Brain rotates images upright.
3. Brain stiches images togehter.

The first would work, but takes more processing steps. The second wouldn't work at all. The third is most efficient.

But you were suggesting upright wouldn't need to be upright. So it could have done this:

1. Image hits the retina.
2. Brain corrects the left-right orientation.
3. Brain stitches the images together (leaving them upside-down).

zomgwtf

Evolution doesn't work base on what's needed or what's better, it just works based on the history of things. I'll have to look further into it to see if there indeed is an evolutionary advantage to the brain adjustment for uprightness but right now I have to go to work :P. I shall respond later.

Monique

Here is another interesting article: Right-Side Up - Studies of perception show the importance of being upright Figure F is really striking.

Proton Soup

yup, first thing i thought about before even opening it.

Monique

To get back on the comment that gravity has nothing to do with it. Here is an interesting publication that illustrates how our brain can misinterpret its sensory information and make a wrong decision on orientation. Interestingly, this shows that we need the input of gravity to define our 3-dimensional world and that indeed when this is messed up you "jump instead of duck" in a situation of danger (like how it was mentioned earlier in this thread).

lorax_2nd

I feel a bit woozy, but think I am dumber now after having read this thread, than before I came. Which isn't easy to do, because I'm fairly stupid to begin with.

Once upon a time, when someone wanted to ask a physics question, they had to take the effort to physically go find someone acknowledged as a physics 'expert' (or, the usual substitute: your local jr. high physics teacher), and if that person wanted to give a more thoughtful answer than whatever came off the top of their head at the moment, they had to physically go to a repository of information (or, the usual substitute: their dusty bookshelf) and consult tomes of peer-reviewed articles, or for more general questions, textbooks. This forced people to invest time in learning, and sometimes, that investment filtered out some nonsense.

Now, someone can post an ill-framed question that popped into their head 10 seconds ago, have it seen by thousands, and be responded to by anonymous anyones (like me) with answers that just popped into their own head, or possibly worse, with googled keyword articles. Again, I have to ask, is a useful piece of physics being learned, or do I fundamentally misunderstand the purpose of a physics forum?

As for the charge of disrespect: I'll plead guilty, yer honor. Respect me if I give a clear, concise answer with my assumptions defined, terms commonly used and understood, and conclusion relevent to the original question, and I'll do likewise.

I genuinely feel bad for sounding like such a curmudgeon, but I can't help but express my disappointment, even if I'm just saying it to myself, and seeing it in print, and inflicting my opinion on other people. ...And so doing no better than what I'm criticizing...

zomgwtf

Are you being serious? If you know the definitive answer then post it with some citations. Which posts make you feel 'dumber' than you already had been???

Really? There are some pretty knowledgable people in the field of biology on these forums and yes, they have made posts in this thread. I'm no expert (yet at least I'm studying to) and if something I've said is wrong could you point it out?... if something anyone has said is wrong why don't you just point it out? Instead of this unnecessary posting?

I doubt that the people on these forums did a simple google keyword search and threw non-sense out there. This isn't physics being discussed here... in fact it's FAR removed from physics. Just because the forums name is PhysicsForums doesn't mean everything discussed on the forums is related to physics. The posed question has to do with the necessity of our brain 'correcting' for inversion of our vision.

Where was your concise answer again? All I read was you explaining that what we see is inverted and why it was inverted... I might have missed something though. By the way when you see something inverted it doesn't mean your hands are moving towards your feet and you see them moving some other way.

zomgwtf

Hmph forgot to come back to respond to this thread.
Glasses you wear on your eyes which invert what you are seeing.
No I don't think that's what I was saying. I was saying this:
1. Image hits retina
2. Image gets assembled correctly (so we see it as one seemless image that is)
3. Image appears 'upright' automatically, it's not 'rotated' it just looks upright because it's normal to see things that way.

Point 3 is what I've been trying to point out. It just 'happens' as a 'correction' (I can't think of a better word... it's really not a correction though) So while the image received very well may be inverted our brain forces us to perceive it 'upright' because it's the norm. We are used to observing things in that orientation and this orientation is based on our body. This is honestly a very confusing thing to try and explain... I may be wrong in my thinking but this is just what I've been trying to explain here in this thread.

This is basically what I think goes on with the exception that the brain automatically perceives the image as upright, because it is normal to the brain. As I said before you can put on the inversion glasses and after awhile things appear normal, this is your brain automatically forcing you to perceive things as upright based on your body.

Why is this needed though? That's the OPs question. After reading the article that Monique posted it became clear to me why it would be necessary to make this 'correction'... I don't even know why it never occured to me in the first place, I think someone already mentioned it earlier though. I believe it would be necessary to make this correction in order for things in the outside world to appear upright regardless of our bodies orientation. So if I'm laying down on my side I know where up is still in relation to my bodies normal position. (upright) Sorry for dragging this out if this was what you're original point was russ. I just didn't agree with the efficiency part of consciously thinking where things were, that just didn't make sense to me since it would just be the norm for our brain.
I do not believe it is left upside-down. The brain just automatically forces you to perceive the image upright.

lorax_2nd

You're right, my last post wasn't realistically constructive. Upon re-reading the whole thing, based upon the OP's subsequent posts, it seems clear that he wasn't looking for a brief, simple physics answer, but rather appreciated the thread's various discussions.

That's not my cup of tea, so ... I'm moving along... :)

Monique

There you go again with your disrespect. May I summarize the source that I have cited? Here they are:

• G. M. Stratton, Third International Congress for Psychology, Munich, August, 1896
• L.E. White, D. Fitzpatrick, Neuron. 2007 Oct 25;56(2):327-38.
• V.S. Ramachandran and D. Rogers-Ramachandran, Scientific American Mind, July 2007
• R. Kalb; D. Solomon, Archives of Neurology, 2007;64(4):485-490.

Get out of your little box. You think you can understand the brain, by explaining the properties of light and the optics of the eye. Check the source again that I cited, by Dr. Ramachandran. Apparently you are not familiar with his work, so let me introduce him: he is Director of the Center for Brain and Cognition and Professor with the Psychology Department and Neurosciences Program at the University of California, San Diego, and Adjunct Professor of Biology at the Salk Institute.

You may want to educate yourself and actually read up on the sources given.

zomgwtf

Hey, there's nothing wrong with adding additional details that you think might be interesting to someone, I'm sure SOMEONE who stumbles accross this thread will find it interesting. However there are ways to go about responding to people on the forum and the way you've chosen isn't one of them. This obviously doesn't apply to just the forum it applies to your outside life, you should always try to remain respectful towards others especially people like Monique who are very respected individuals. I like that you've taken the time to understand and accept that your criticisms of the thread are wrong but you should still try to be more respectful towards others on the internet and in the real world. I know I've crossed the line into disrespecting others before on the forums and in real life and really, it's not worth it.