That's what some martial arts novels say about eye training. You should always stare at mosquitoes in the dark and watch them as big as a millstone. When you see mosquitoes flapping their wings slowly, you will know at once, and then you can hold their wings with your hands, so you can practice martial arts.

Even though he didn't see the flapping of mosquito wings clearly, Xia still saw the blades of the fan. Even if he didn't practice 10, he probably reached 89, which is worth celebrating.

People see some details of fan blades or other high-speed objects, which have nothing to do with practicing martial arts. It is a basic function of human eyes and brain.

This is actually caused by a phenomenon of visual persistence.

Visual persistence is a characteristic of human eyes and a reflection of retinal light retention.

People can only see objects when the retina is sensitive. When the light of an object reaches the human retina, it will form an image and enter the human brain through the optic nerve, making people feel the appearance of the object. This feeling will not disappear suddenly with the removal of the object, but will remain for a certain time, which is the phenomenon of visual persistence.

This phenomenon is due to the fact that retinal photosensitive imaging and optic nerve transmission take a certain time, and it is also the result of long-term evolution of human beings.

Studies show that this visual persistence lasts 0. 1~0.4 seconds.

It is this effect that people can see not only the blades of fans, but also the blades of airplane propellers. Sometimes the propeller of an airplane seems to stop turning or even reverse.

But to see this phenomenon, the speed of the object must be suitable for the reaction characteristics of the human eye and the human brain, and it is not good to be fast or slow.

People have studied this phenomenon for nearly 300 years. This phenomenon was first put forward by Peter, a professor at University of London, England. Mark? Roget, who expounded this phenomenon in the research report "Visual Persistence of Moving Objects" published in 1824.

Later, many scientists studied this phenomenon and it was quite controversial.

William? Benjamin? Carpenter thinks in a paper in 1868 that the so-called? Optical toys? Motion effect is caused by residual images on retina. What do you think is the illusion effect? Spirit? Instead of. Retinal phenomenon? .

So whether this phenomenon is due to brain mechanism or retinal mechanism is still controversial.

Nevertheless, the creation of human beings using this phenomenon to enrich their lives has begun.

Some studies believe that the phenomenon of visual persistence first appeared in China, and the way of this application is to run the lantern. The time when the lantern appeared was in the Song Dynasty, when there was no theory of visual persistence.

Then the Frenchman Paul? Roger invented the photographic disc in 1928.

This plate is painted with a bird on one side and a cage on the other. When the disc is quickly turned over, birds will appear in the birdcage, which proves that the human eye can synthesize two different images into one image through visual persistence.

1829, the famous Belgian physicist Joseph Prado also began to study the phenomenon of visual persistence, which was invented in 1832? Cheating? , this kind? Cheating? The image drawn on the serrated cardboard box can be moved.

1834, Halner, USA? Movable video? The test was successful; 1853, Austrian general von Uchetis showed the original cartoon with a slide show, and the prototype of the film appeared.

Finally, the ultimate invention of visual persistence effect-film has entered human life.

1888 10, French film inventor Louis? Prince showed the world's first film, which was a scene of Langdehai Garden and a street view of Leeds Bridge shot continuously with Kodak's paper film.

Since then, movies have entered human life. The film is to use the visual persistence phenomenon of human eyes, 24 frames per second. Through the visual persistence effect, people can see a discontinuous picture and turn it into a continuous picture.

The visual persistence in the retina can reach 0. 1~0.4 seconds, while the movie uses 24 frames per second and only needs 0.04 seconds of visual persistence, so the movie pictures people see are seamless and very smooth.

The study of visual persistence involves the multidisciplinary research of brain science and ophthalmology, and its complex mechanism needs to be further revealed, but there is no doubt about the existence of this phenomenon.