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

Pythagorean

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

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

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

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 dont do either of those consciously!

DaveC426913

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

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

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

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

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.


That is really interesting.

Pythagorean

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: Vision and cortical map development.

DaveC426913

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

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

DaveC426913

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?