seeing things up-side-down

[gib65]

Everyone knows that the eyes invert incoming light so that the image projected on the retina is an up-side-down version of what's out there. I've also been told that the brain corrects for this so that we don't see the world as up-side-down. But what does it mean to say that the brain "corrects for this". Does it mean...

 

1) that the brain interprets the incoming signals as right-side-up so that we don't feel like we're standing on the ceiling, or...

 

2) that there is a physical correction somewhere between the retina and area V1 (back of the brain), like the nerve fibres cross over somewhere along the optic nerve so that whatever light hits the top of the retina comes in at the bottom of area V1.

 

Note the difference: 1) says that the real world is actual what we would consider "up-side-down" but the brain just makes the perceived world feel right-side-up. 2) says that the real world and the perceptual world are exactly the same.

 

Which is it? If it's 2), then where/how does the brain make the correction?

[Glider]

It's 1. The brain corrects the image. About half the fibres cross over at the optic chiasm, but this is a lateral crossover.

 

There is an interesting phenomenon you can experience yourself (it used to be one of those 'public participation' things you could do at the Science museum in London) whereby you wear glasses that invert the image so everything appears upside down. For a while it's very hard to function, but after a short time, the brain compensates and things appear normal.

 

The tricky bit is, after you have adsjusted, you take the glasses off, and everything appears upside down again until the brain readjusts.

[5614]

For a while it's very hard to function, but after a short time, the brain compensates and things appear normal.

Really? I really wanna try that now, I believe you, I just want to experience that!

[badchad]

During my graduate work, I did a rotation in a laboratory that at things such as this. Essentially we surgically rotated an eye in a xenopus frog early in development.

 

They adapted and compensated for this.

[gib65]

It's 1. The brain corrects the image. About half the fibres cross over at the optic chiasm' date=' but this is a lateral crossover.

 

There is an interesting phenomenon you can experience yourself (it used to be one of those 'public participation' things you could do at the Science museum in London) whereby you wear glasses that invert the image so everything appears upside down. For a while it's very hard to function, but after a short time, the brain compensates and things appear normal.

 

The tricky bit is, after you have adsjusted, you take the glasses off, and everything appears upside down again until the brain readjusts.[/quote']

 

That's neat! When you say "appears normal", I assume you don't mean the world actually gets flipped right-side-up. Do you mean we just get used to it and that it ends up feeling normal?

 

PS - Where can I get me a pair of glasses like this?

[Glider]

To be honest, I don't really know, as I never tried it myself (I wish I had though). The brain definitely compensates so you can function, and I believe inverts the image after about 10-15 minutes, which is why removal of the goggles makes everything appear uside down again, but as I say, I can't be sure, never having done it myself.

 

You should be able to find prism goggles somwhere to try it out for yourself. That should be fun

[CharonY]

When I was still studying we had a course toying around with those glasses. I did not try them on, but those that did described it as Glider said.

 

It took around 5 -25 minutes (depending on the person), if I remember correctly to readapt.

If you are interested and have a library near you here are some (old) papers dealing with it (JFYI).

 

Stratton, G. (1896). Some preliminary experiments on vision without inversion of the retinal image. Psychological Review, 3, 611-617;

Stratton, G. (1897). Upright vision and the retinal image. Psychological Review, 4, 182-187.

Dolezal, H. (1982). Living in a world transformed. Chicago: Academic Press;

Kohler, I. (1964). the formation and transformation of the perceptual world. New York: International University Press.

[jordan]

I remember watching some little documentary about those kinds of glasses in a psychology class. They were following a lady who was going to wear them for a week or so (at all times). At first she had trouble doing the most basic things, but soon she got that. Then fine motor skills were her only problem and after a day or two she could do just about anything at a normal rate (I don't think they let her drive while doing this though). By the end of the experiment, she had to conciously imagine what it was like to see things the 'right way' again. Her body had totally adjusted to the inverted glasses and she no longer noticed any difference from the way her vision used to be. Then, like Glider said, she had to take them off and the whole process started again...