Trichromatic colour vision, also known as normal colour vision, allows humans and some other animals to distinguish a wide range of colours due to the presence of three types of cone cells in the retina. Each of these types of cone cells is sensitive to a different range of wavelengths of light, corresponding roughly to blue, green, and red. The brain interprets the signals from these cones to create the perception of different colours.
- Cone cells: Unlike rod cells, which primarily detect light and darkness, cone cells are responsible for colour vision. There are three different types of cone cells in the human retina:
- S-cones: Most sensitive to short wavelengths (blue light)
- M-cones: Most sensitive to medium wavelengths (green light)
- L-cones: Most sensitive to long wavelengths (red light)
- Colour perception: When light enters the eye, it stimulates the cone cells based on its wavelength. The brain then receives signals from these cones and interprets their combination as specific colours.
- If all three types of cone cells are stimulated in different proportions, the brain perceives a mixed colour. For example, a combination of strong red and green stimulation might be perceived as yellow.
- If only one type of cone cell is stimulated, the brain perceives the corresponding primary colour (blue, green, or red). However, due to overlapping sensitivities of the cones, pure primary colours are rarely seen in real life.
- Variations in colour vision: While trichromatic vision is considered normal, there are variations in individual sensitivities and slight differences in the distribution of cone cells. This can lead to subtle differences in colour perception between people.
- Comparison to dichromatic vision: Individuals with dichromatic vision only have two types of functional cone cells, leading to difficulties distinguishing certain colours, particularly red and green.
References
- Trichromatic colour vision, also known as normal colour vision, allows humans and some other animals to distinguish a wide range of colours due to the presence of three types of cone cells in the retina. Each of these types of cone cells is sensitive to a different range of wavelengths of light, corresponding roughly to blue, green, and red. The brain interprets the signals from these cones to create the perception of different colours.
- There are three different types of cone cells in the human retina:
- S-cones: Most sensitive to short wavelengths (blue light)
- M-cones: Most sensitive to medium wavelengths (green light)
- L-cones: Most sensitive to long wavelengths (red light)
- When light enters the eye, it stimulates these cone cells according to the wavelengths it contains. The brain then receives signals from these cones and interprets their combination as specific colours.