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Essay: How Do the Brain and Eyes Jointly Process Visual Information

Human vision is a complex process. The brain is the central data processing device, which interprets all the neurological messages that come from all over the body. The eye is an external device like any other sensitive body organ. It is located inside conducting research for the brain.

Man exists in a diverse world of things, situations, and words. The external world is reflected in our consciousness through the senses. It is well known that 90% of all the information people receive through their eyes. However, today science has proved that people actually hear not through their ears and see not through their eyes but through the relevant sections of the cortex, which covers both hemispheres of human brain (Blakemore & Frith, 2005, p. 122). Let us turn to well-known scientific facts. German physicist Hermann Von Helmholtz found that under the laws of optical physics at the snapshots, made by the retina, a surrounded world is captured upside down. Namely, in this way, infants see it at first. As a child is growing up, the brain makes adjustments in the inverted image (Simos, 2001, p. 127).

The presence of two eyes creates a different visual perception of reality by one and other eye: having made the shots, first, from the point of the left eye, and then from the right eye, we get a few different images at the two pictures. Consequently, the images in the visual centers of the left and right cerebral hemispheres are not entirely identical, and only the brain establishes a connection between the areas of the visual cortex in both hemispheres and, obtaining information from the left and right, builds a single image of a subject, harboring the shortcomings of each eye.

One of the leading modern linguists, American linguist Noam Chomsky, in the course of his lectures held in 1987 at the University of Managua, said that only a man, unlike animals, has the eye-brain system that following the principle of invariance can interpret the constant object in motion. For example, a flat shape in the form of the circle when turning 90 degrees is seen not as flat and changing, till turning into a line and the complete disappearance, but, invariably, as in the form of a rotating circle. As well Chomsky presents another example of the phenomenon known as apparent motion (arising, in particular, on the TV screen) (Blakemore & Frith, 2005, p. 143).

The eyes are closely linked to the brain, from which they evolved. Eyes are even called “brain bubbles”. When a beam of light hits the retina, chemical reactions occur in it, which are converted into nerve impulse. This impulse is sent to the brain. What the brain “sees” is very different from the image on the retina. When we look around ourselves, our mind instantly flutters from one object to another. At the retina it is occurred a “cinema” of the rapidly changing color pictures. The brain does not see the same series of instantaneous photographs. Visual center captures every “frame” and remembers it. Then all these “frames” are united and the brain analyzes the entire picture. Immediately, the seen image is compared with the image, which is seen earlier. At this moment, we are aware of the object before us (Kaplan, 2002, p. 98).

Namely, the brain helps us to see objects in three dimensions rather than flat. The brain sees the perspective, the distance from object what we see. This is because the brain “remembers” shape and size of previously seen objects and subjects. For example, the eye sees a large dog and a small truck running on the road. The brain receives this information and, knowing the true size of the dog and the machines, “savvies”. The dog is near, the truck is far. All of this happens instantly, so we are confident that the eye itself sees it this way (Al-Chalabi, 2008, p. 115).

Indeed, more than 90% of information from the outside world we get through the eye. This is possible because we have one of the most beautiful visual systems in the world. Without it, our lives would take place in the dark. Our eyes have a perfect structure, providing us with three-dimensional, color vision with high visual sharpness. They can quickly change the focus to different distances, regulate the amount of incoming light, distinguish between hundreds of thousands of different colors and shades, and correct spherical and chromatic aberrations. The eye is linked to the brain by the six levels of the retina, where, before sending information to the brain, there is compression of the data (Schwartz, 2008, p. 109). The brain sorts, processes, and analyzes the signals received from the eyes, and then creates a single image from the individual signals. There is still much to learn about the work of the brain, but what we know is amazing. By means of two eyes, two images of the world around us are formed simultaneously by one image on the retina of each eye, which are transmitted to the brain (Gregory, 1997, p. 126).

How, then, we are not seeing two images at once? It turns out that each point of the retina in one eye corresponds to point of the retina in the other, so that two images may be applied or combined together in the brain to obtain a single image. Data from the photoreceptors of the corresponding points come together in the visual cortex of brain, creating a single image. Because of the different projection of the eye to the object, the small discrepancies may arise, but our brain “drains” pictures in such a way that we do not feel them. Moreover, it knows how to use these inconsistencies to get a sense of spatial depth.

Further, despite the fact that the received images on the retina are miniature and turned upside down (as a result of refraction of light) the brain gives us a normal image of the seen. In addition, the brain “cuts” the image of the retina into halves, along the line running vertically through the pit of the retina. The left halves of the images of both eyes are sent to the right hemisphere of the brain and the right halves of the images of both eyes are sent to the left hemisphere. Each hemisphere of the brain receives information from only the one half of the image. As explained by Dr. W. Gitt, although the brain processes the different parts of the image, the two halves evenly combined again and without a trace of the compounds. This process has not yet been investigated to the end (Hoffman, 2000, p. 214).

It is impossible that such system could occur through the evolution. Due to the separation of images and complex optical paths, the brain “sees” by each hemisphere separately through each eye. This design was created to expedite the processing of data as well as to ensure that in case of injury or loss of an eye the brain continued to see through the remaining eye.

Bibliography

  • Al-Chalabi, A. (2008). The Brain: A Beginner’s Guide. Oneworld Publications.
  • Blakemore, S.J., & Frith, U. (2005). The Learning Brain: lessons for education. Oxford: Blackwell Publishing.
  • Gregory R. L. (1997). Eye and Brain. Princeton University Press.
  • Hoffman, D.D. (2000). Visual Intelligence: How We Create What We See. New York: W.W. Norton & Co.
  • Kaplan, R. (2002). Conscious Seeing: Transforming Your Life through Your Eyes. Atria Books/Beyond Words.
  • Schwartz, G.S. (2008). Around the Eye in 365 Days. Slack Incorporated.
  • Simos, P.G. (2001). Vision in the Brain. Taylor & Francis.
June 19, 2012Tags: , ,