Theories Of The Tri-Chromatic Theory Of Color Vision

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Theories of Color Vision

The visual abilities of human beings are incredibly fascinating. We can view a large range of color from a small choice of wavelengths along the electromagnetic spectrum, 400nm-700nm. Our understanding of this perception of color comes from two major theories Tri-chromatic theory of color vision and opponent-process theory. Both theories have their merits and one actually grew out of the other. The first theory proposed was the tri-chromatic theory.

The tri-chromatic theory of color vision states that our color vision is dependent on activity of our three color receptors. It goes on to say that the mixture of these three independent wavelengths for color could produce any other given color on the visual spectrum.
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They are usually associated with retinal receptor problems as opposed to brain damage. There are three types of color deficiencies that branch to a number of other problems; monochromatic, dichromatic and anomalous trichromatic. Monochromatic color perception is hereditary and causes one to have no function cones. That is, the people affected by this see in black and white. Dichromatic color perception is involved with the ability to see some color but is caused by a deficit in one of the three cone receptors, that is only two work. Protanopes are dichromats that have a deficit in the "red" cone, deutranopes have a deficit in the "green" cone and tritaneropes have a deficit in "blue" cones. Images of the color these people would be able to see is in figure 1 on page 6. Anomalous trichromatic color vision happens when wavelengths get mixed in different proportions than a regular trichromatic. This leads to one being less efficient at discriminating between wavelengths of color closer together. An example of what an anomalous trichromatic might see is seen in figure 2 on page 6. Trichromatic theory of color is not the only theory of color we use though. There is also opponent-processing theory of color …show more content…
It states that viewing a red field will generate a green after image, green field generate red after images, yellow fields generate blue after images and vice versa. Tri-chromatic theory cannot explain why red/green and blue/yellow are paired with these after images. It also cannot explain the simultaneous color contrast. This is the effect of the color of a surrounding area having an effect on perception of color in said surrounding area. Also that people who are color blind to red also tend to be color blind to green and people who cannot see blue can not see yellow. These all led to the conclusion that red/green and blue/yellow were paired. These conclusions lead to Edwald Hering (1878,1905,1964) to propose the opponent-process theory of color vision. He proposed three mechanisms on why vision is an "opponent" process. The first is a black (-)/white ( ) mechanism, the second a red ( )/green (-) mechanism, and the third a blue (-)/yellow ( ) mechanism. He said the positive or negative responses was a function of a building up or breaking down of chemicals in the retina. White, yellow and red were contributing to a reaction that caused build up while black, green, and blue were contributing to the breakdown. Hering 's theory was not completely correct, but research has shown physiologically that these colors do in fact cause opposite physiological

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