The imaging principle of animal eyes is similar to that of convex lens imaging, except that it is a little more complicated than the convex lens imaging experiment we did in high school because the eye has a complete set of imaging systems. As we all know, light passing through a convex lens will obtain a real image. As long as you have some basic physics knowledge, you will know that any real image is inverted.
In other words, our eyes are actually providing our brains with an inverted image all the time, but our brains have adapted to this so that we feel everything is normal.
So the interesting question is, what if we use some technology to let our eyes see a normal upright image?
Someone actually did such an experiment. In the middle of the 20th century,An Austrian professor turned one man's vision completely upside down.
Picture: Professor Erisman and Kohler
Professor Theodor Erismann of the University of Innsbruck designed this experiment, and the person who accepted the challenge was his assistant Ivo Kohler.
Khloe later wrote about it, and the two of them made a documentary together, so we can see what it would be like to turn the world upside down.
Professor Erisman designed a pair of glasses with a mirror inside that flipped the light so that the top became the bottom and the bottom became the top.
Assistant Kohler then put on the special glasses, and according to Kohler's description, he initially had difficulty trying to grasp objects handed to him, often falling badly while walking around chairs or walking down stairs.
When he picked up the teacup to pour water, he saw that the water was obviously pouring upwards, so he unconsciously turned the teacup upside down.
He would at some point become disoriented when he saw the smoke rising from a match, or the sight of a balloon bouncing up and down on a string.
In the experiment, Kohler also tested fencing, in a simple fencing match where he would raise the club high for a low attack and lower for a high thrust.
But over the next week, Kohler found himself adjusting to the sights intermittently, then more consistently, until ten days later, he was fully accustomed to a world forever turned upside down.
Paradoxically and happily, his perception is not that the world is upside down, but that it is right side up, and everything seems normal to him.
After ten days, Khloe was able to complete daily activities in public very well:Walk along crowded sidewalks or even ride your bike.
Passers-by on the street did glance at the man, though, because from the outside, his glasses looked special.
After Erisman and Kohler, many other scholars conducted similar experiments, and all of them obtained similar results. The experimenters eventually adapted to inverting what they saw with their eyes.
Not only is it upside down, people can also adapt to the left and right world in a short period of time. In the left and right experiments, the subjects could ride a motorcycle on the road after a few weeks without any impact.
While not everyone has had such a test, most scientists agree that perhaps all of us can do both.
Picture: There is also this kind of device that adjusts left and right and up and down.
This strange, automatic, and almost effortless adaptation to vision is one of many strange things the brain does that scientists currently simply cannot understand.
There are many unique things about our vision that also appear after modification by the brain.
For example, our eyes are actually cameras, and they only get a two-dimensional image. But as you feel, our world has depth and is three-dimensional. This is also the result of the brain.
Compared with how the brain modifies the world to normal, the reason why it turns 2D into 3D is relatively clear. There are two main ways, one is relative size, and the other is the cooperation of the eyes.
It is a fact that the depth we see is the result of binocular vision. The perception of depth is only experienced when two eyes are looking at a scene at the same time. This is because each eye detects light from a different angle, and it is these two sources of visual input that our brains process for depth perception.