Download Atheism - Color: It`s What You Perceive

Newton’s Theory of Color
SIR ISAAC NEWTON (1642-1726) discovered that when pure
white light passes through a prism, a multi-faceted array of colors
resembling a rainbow becomes visible. Based on his findings he
created the first color wheel differentiating and defining color in
what is called the visible spectrum. The color wheel consists of
primary colors known as red, yellow and blue and when mixed create the secondary colors of
orange, purple and green. Color then advances by the mixing of the primary and secondary colors
to form tertiary colors. Newton published “Opticks” in 1704 which detailed his findings.
Young-Helmholtz Trichromatic Theory of Color Vision
In the mid 1800’s Herman von Helmholtz (1821-1894), based on the initial findings of Thomas
Young (1773-1829), developed the Young-Helmholtz Theory of Color Vision. Young had originally
speculated that 3 sets of nerve fibers were necessary in order for the eye to perceive color. Based on
later experimentation Helmholtz discovered that in order for us to experience normal color vision,
three wavelengths of light are required. Every color in the color spectrum is composed from the
mixing of these red, blue and green wavelengths. He performed color matching experiments and
found that every person tested could ultimately match any given color by adjusting these 3
wavelengths. In the retina of the eye there are photosensitive pigments that respond to these various
wavelengths of light. They respond to the light and interact to enable us to differentiate colors. It
was not until many years later that researchers identified the three receptors, called cones, located in
the retina used to receive the short (S), medium (M) and long (L) wavelengths to produce color. This
became known as the trichromatic theory of color vision. Later research also revealed the existence
of other photoreceptors in the retina known as rods which are more sensitive than the cones, but do
not distinguish color.
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Opponent Processing Theory
The Opponent Process Theory of color was developed by Ewald Hering in 1892. Hering realized
that there are some color patterns that don’t mix, like hues of greens and reds and hues of yellows
and blues. He could not reconcile the reasons for this in the previously established Trichromatic
Theory. Hering hypothesized that color perception is governed by two opponent systems: the blueyellow mechanism, as well as the red-green mechanism. In the blue-yellow mechanism, blue and
yellow are opponents and in the red-green mechanism, red and green are opponents. These colors
are called “opponents” because they are controlled by opponent neurons: excitatory and inhibitory
neurons. These neurons react to the different wavelengths of colors. In the red-green mechanism,
excitatory neurons react to the wavelengths of the color red, while inhibitive neurons react to the
wavelength of the color green. Activity in one pair of the mechanism inhibits activity in the other.
This is why we perceive after-images when staring at a particular color for a long period of time.
For example, when looking at a blue dot for 30 seconds or more, if one were to shift their gaze to a
blank, white surface, one would see a yellow dot. The reason for this is when one pair of the
opponent mechanisms was being used for an extended period of time the opposite neurons that
react to yellow were being inhibited. However, when the gaze shifts to a blank surface, the neurons
that reacted to the blue wavelength are no longer stimulated. Consequently, the neurons that react
to yellow, which were being inhibited by the over-activity of their opponents finally increase
activity. Therefore, in one’s mind, one sees the opponent color, yellow.
It was the later work of Dr. Leo M. Hurvich (1910-2009) and Dorothea Jameson (1920-1998)
which united these two theories. Their research proved that elements of both theories were
necessary and worked in conjunction with each other to create our perception of color.
Munsell Color System
In 1898 Albert Munsell began the creation of a decimal system to describe color which was detailed
in his publication of A Color Notation in 1905. He used the terms hue, value and chroma to
systematically evaluate the dimensions of color. Munsell defined hue as "the quality by which we
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distinguish one color from another.” He defined value as "the quality by which we distinguish a
light color from a dark one", and chroma as “the quality that distinguishes the difference from a
pure hue to a gray shade”. His description of color is still widely used today.
This system is defined as a subtractive system using RYB (red, yellow, blue).
Another system is an additive system which is used to refine color on
televisions and computer monitors and is identified as RGB (red, green, blue).
And in printing CMYK (cyan, magenta, yellow and black) are used to create
colors.
References
1. George Szekeres (1948), "A New Determination of the Young-Helmholtz Primaries, Journal of
the Optical Society of America (JOSA), Vol. 38, Issue 4, pp. 350-363 retrieved from
http://dx.doi.org/10.1364/JOSA.38.000350
2. University of Rochester (2005, October 26). Color Perception Is Not In The Eye Of The
Beholder: It's In The Brain. ScienceDaily. Retrieved from
http://www.sciencedaily.com/releases/2005/10/051026082313.htm
3. Goldstein, E. Bruce (2010). Sensation and Perception. Belmont, CA, Cengage Learning
4. Cherry, K. (n.d.). What is the opponent-process theory of color vision?. Retrieved from
http://psychology.about.com/od/sensationandperception/f/opponproc.htm
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5. Kaiser, P. K. (1996). The joys of visual perception: Opponent processing theory of color vision.
Retrieved from http://www.yorku.ca/eye/opponent.htm
6. randomactsofscience.squarespace.com
4. http://www.webexhibits.org/colorart/bh.html
5. http://en.wikipedia.org/wiki/Color_vision
6. http://www.colormatters.com/
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