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Color blindness is any deviation of color vision from normal trichromatic color vision (often as defined by the standard observer) that produces a reduced gamut. Mechanisms for color blindness are related to the functionality of cone cells , and often to the expression of photopsins , the photopigments that 'catch' photons and thereby convert ...
Dichromacy in humans is a form of color blindness (color vision deficiency). Normal human color vision is trichromatic, so dichromacy is achieved by losing functionality of one of the three cone cells. The classification of human dichromacy depends on which cone is missing: Protanopia is a severe form of red-green color blindness, in which the ...
Unique hues can differ between individuals and are often used in psychophysical research to measure variations in color perception due to color-vision deficiencies or color adaptation. [4] While there is considerable inter-subject variability when defining unique hues experimentally, [ 3 ] an individual's unique hues are very consistent, to ...
Opponent-process theory is a psychological and neurological model that accounts for a wide range of behaviors, including color vision. This model was first proposed in 1878 by Ewald Hering , a German physiologist, and later expanded by Richard Solomon , a 20th-century psychologist.
The second most common PIP color vision standard is the HRR color test (developed by Hardy, Rand, and Rittler), which solves many of the criticisms of the Ishihara test. For example, it detects blue-yellow color blindness, is less susceptible to memorization and uses shapes, so it is accessible to the illiterate and young children. [2]
For example, staring at a saturated primary-color field and then looking at a white object results in an opposing shift in hue, causing an afterimage of the complementary color. Exploration of the color space outside the range of "real colors" by this means is major corroborating evidence for the opponent-process theory of color vision.
Color blindness (or color vision deficiency) is a defect of normal color vision.Because color blindness is a symptom of several genetic and acquired conditions, the severity can range drastically from monochromacy (no color vision) to anomalous trichromacy (can be as mild as being indistinguishable from normal color vision).
Research has shown that scores below twelve indicate color vision deficiency, and twelve or more correct indicate normal color vision, with 97% sensitivity and 100% specificity. The sensitivity of the Ishihara test varies by the number of plates allowed to pass, which can vary by institutional policy.