Trichromacy

Trichromacy is a condition of the visual system where it is sensitive to three different parts of the spectrum. This condition is typical in humans and some other primates. Trichromacy is achieved through the combination of the responses from three different types of cone cells in the eye. Each type of cone cell responds to a different range of light wavelengths. The three types of cone cells are often referred to as short-wavelength (S), middle-wavelength (M), and long-wavelength (L) cones.

Physiology

The human eye contains three types of cone cells, each of which is sensitive to a different range of wavelengths. The S-cones are most sensitive to light that is perceived as blue, the M-cones are most sensitive to light that is perceived as green, and the L-cones are most sensitive to light that is perceived as red. The combination of the responses from these three types of cone cells allows humans to perceive a wide range of colors.

Types of Trichromacy

There are two types of trichromacy: normal trichromacy and anomalous trichromacy. Normal trichromacy is the condition most humans have, where all three types of cone cells are present and functioning correctly. Anomalous trichromacy is a condition where one of the three types of cone cells is not functioning correctly, resulting in a reduced ability to distinguish between certain colors.

Evolution

The evolution of trichromacy in primates is believed to have been driven by the need to distinguish ripe fruit and edible leaves from the surrounding foliage. This is supported by the fact that the M and L cones in primates are most sensitive to the colors of ripe fruit and young leaves.

See also

• Color vision
• Cone cell
• Color blindness
• Dichromacy

References

Trichromacy Resources
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