Trichromatic Theory - Essay Example

Trichromatic theory Trichromatic theory Different people are able to identify different colors due to intrinsic characteristics of the retina. The ability of individuals to differentiate colors due to interactions among three kinds of cone cells which sense color is called Trichromatic color vision. If the retina has some problems, one finds it hard to differentiate colors and consequently he/she is considered to be color blind. Different colors produce light of different wavelengths which make retina able to differentiate them.

In this paper, Trichromatic theory of color vision is discussed. Trichromatic theory was proposed by Thomas Young in 1802 and later improved in 1852, by Hermann von Helmholtz (Briggs, 2011). As per this theory, people’s color vision is as a result of combined sensitivity to blue, green and red colors. Every other color comes out of specific combination of these three colors which causes specific response from the retina. The theory is supported by scientific finding that there exist three different color sensitive cone receptors in eye retina (Briggs, 2011).

Each set of receptors is sensitive to color of different wavelength. Different sets of receptors are either sensitive to short, long or medium wavelength. Examples of colors in these wavelengths are blue, red and green respectively. Combination of red, blue and green in any ratio results into various color intensities which are interpreted by the brain after corresponding signals are sent from eye retina (Gibson, n.d). When the three nerve sets are stimulated, they produce sensations of green, Blue and red.

Interpretation of these sensations is achieved through weighing their relative intensities after which their color percept is produced (Pillow, 2010). Humans’ trichromacy evolved from pigments inherited from early vertebrates. Other primates are also trichromats and their eyes have three sets of cones for short wavelength, medium wavelength and long wavelength just like humans (Briggs, 2011). Research has shown that ganglion and special bipolar cells only allows signals with short wavelength.

This means that there are different pathways for signals of various wavelengths through thalamus tissue to visual cortex. People with normal vision are able to use these cells to create normal range of colors (Gibson, n.d). Three cone types in eye retina contain different kinds of photosensitive pigments composed of trans-membrane protein known as opsin. There is also 11-cis retinal which is a light sensitive molecule (Gibson, n.d). Each pigment is sensitive to specific wavelength of light and therefore, color signals are only generated if the pigment is struck by a photon with that specific wavelength (Pillow, 2010).

The short wavelength cones are sensitive to wavelengths of about 420 nm, medium wavelength cones are sensitive to wavelengths of about 530 nm, and long wavelength cones are sensitive to wavelengths of about 560 nm (Briggs, 2011). Interpretation of color in human brain is based on the wavelength and intensity of recorded signal. Each time a signal is send to the brain; its intensity and color are interpreted. More than one cell is used to interpret color of light and therefore trichromatic color vision is achieved by combinations of cell responses.

An average person is able to distinguish different colors up to seven million (Pillow, 2010). It is clear that the trichromatic theory is based on evidence from color mixing and color matching studies. People with normal color vision need only three wavelengths to identify other wavelengths in visible spectrum. This leads to a conclusion that color vision is achieved through finding the balance of short, long and medium wavelengths. References Briggs, D. 2011. The Dimensions of Color. Retrieved on 6/6/2014 from: http://www.

huevaluechroma.com/032.php Gibson, S. J. n.d. On the Trichromatic Theory of color vision. The Journal of Boston Society of Medical Sciences, pp 179-186. Retrieved on 6/6/2014 from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2121835/pdf/jbsms00028-0020.pdf Pillow, J. 2010. Trichromatic Theory of Color Vision. The University of Texas at Austin Spring. Retrieved on 6/6/2014 from: http://pillowlab.cps.utexas.edu/teaching/CompNeuro10/slides/slides03_Trichromacy.pdf