Table of ContentsView AllTable of ContentsOverviewTrichromatic Theory BackgroundReceptorsColor BlindnessTheories

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Overview

Trichromatic Theory Background

Receptors

Color Blindness

Theories

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According to the trichromatic theory of color vision, also known as the Young-Helmholtz theory, there are three receptors in the retina that are responsible for theperceptionof color.

How Color Vision Works

The retina contains millions of photoreceptors called rods and cones. When light enters the pupil of our eye, it travels to the retina in the back of the eye. When the rods and cones detect light, they send a signal to the brain for interpretation.

The rods are sensitive to light and help us to see in dim lighting, whereas the cones allow us to detect color and detail in normal lighting. Of the three types of color receptors, one is most sensitive to the color green, another to the color blue, and a third to the color red. The combinations of these three colors produce all of the colors that we are capable of perceiving. Researchers suggest that people with normal color vision are able to distinguish between as many as one million different colors.

The ability to perceive any color requires interaction betweenat least twotypes of photoreceptors (dichromatic vision). However, the availability of all three color receptors (trichromatic vision) allows combinations that form all of the visible colors in the spectrum.

Background of Trichromatic Theory

Color is a noteworthy part of our visual experience. It can affect how we interpret things about the world, influence our appetite and mood, and even carry symbolic meaning for some people.

But what exactly explains our experience of color? A number of theories have emerged to explain this phenomenon, and one of the earliest and best-known was the trichromatic theory of color vision.

Renowned researchers Thomas Young and Hermann von Helmholtz contributed to the trichromatic theory. The theory began when Young sided with the unpopular theory that light traveled in the form of a wave, and he calculated the wavelength of each color in the visible light spectrum. In 1802, based on the understanding that combining three colors in different proportions could create all of the colors in the visible spectrum, he suggested the eye only required receptors that were sensitive to three of the color wavelengths (red, yellow, and blue), as opposed to needing a receptor for each color.

Through a series of experiments, Helmholtz demonstrated that people with normal color vision needed to have three unique photoreceptors that were preferentially sensitive to one of the three proposed wavelengths of light in order to perceive all of the colors in the visible light spectrum.

Young Helmholtz TheoryHelmholtz used color-matching experiments where participants would alter the amounts of three different wavelengths of light to match a test color.Participants could not match all the colors if they used only two wavelengths but could match any color in the spectrum if they used three.The theory became known as the Young-Helmholtz theory (also known as the trichromatic theory of color vision).

Young Helmholtz Theory

Helmholtz used color-matching experiments where participants would alter the amounts of three different wavelengths of light to match a test color.Participants could not match all the colors if they used only two wavelengths but could match any color in the spectrum if they used three.The theory became known as the Young-Helmholtz theory (also known as the trichromatic theory of color vision).

Color Receptors

The identification of the three cone receptors responsible for color vision did not occur until more than 70 years after the proposal of the trichromatic theory of color vision. Researchers discovered that pigments in the cones (opsins) have different levels of absorption of light waves.

3 Different Cone ReceptorsShort-wavelength cone receptors (S-cones)Medium-wavelength cone receptors (M-cones)Long-wavelength cone receptors (L-cones)

3 Different Cone Receptors

Short-wavelength cone receptors (S-cones)Medium-wavelength cone receptors (M-cones)Long-wavelength cone receptors (L-cones)

Humans can see wavelengths that span from 400 nanometers (violet) to 700 nanometers (red). The full spectrum of visible light includes seven main colors: red, orange, yellow, green, blue, indigo, and violet (remembered with the mnemonic ROY G BIV).

Each of the three cone receptors is most sensitive to the specific wavelengths of either blue, green, or red and there are a million variations of color when these three are combined. Photoreceptors also tend to have different sensitivity levels. Blue receptors are the most sensitive and red the least.

Most people with normal vision are trichromats, but in rare cases, some women have a genetic mutation giving them four types of cones that allow them to see exponentially more colors than most people. This is known as tetrachromatic vision.

We cannot talk about color vision without mentioning color blindness. The underlying cause of color blindness is a genetic alteration in one or more of the cone pigments.

Types of Color VisionThe four types of color vision include:Monochromatic: 500 shades of grayDichromatic: 10,000 colorsTrichromatic: 1 million colorsTetrachromatic: 100 million colors

Types of Color Vision

The four types of color vision include:Monochromatic: 500 shades of grayDichromatic: 10,000 colorsTrichromatic: 1 million colorsTetrachromatic: 100 million colors

The four types of color vision include:

Trichromatic Theory and Opponent Process Theory

In the past, the trichromatic theory was often presented as competing with theopponent-process theoryfor dominance in explaining color vision. Today, it is believed that both theories can be used to explain how the color vision system operates and that each theory applies to a different level of the visual process.

The highlights:

Takeaway

Color vision and perception is a complex process that involves the eyes and brain. The trichromatic theory explains one part of this process, focusing on the photoreceptors in the eye that then send signals to the brain. Learning more about this aspect of color vision is an important part of understanding how we perceive things about the world that make up our visual experience.

9 SourcesVerywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Lee BB.The evolution of concepts of color vision.Neurociencias. 2008;4(4):209–224.Neitz J, Carroll J, Neitz M.Color vision: Almost reason enough for having eyes.Optics and Photonics News. 2001;12(1):26-33. doi:10.1364/OPN.12.1.000026Piqueras-Fiszman B, Spence C.Colour, pleasantness, and consumption behaviour within a meal.Appetite. 2014;75:165-172. doi:10.1016/j.appet.2014.01.004Elliot AJ.Color and psychological functioning: A review of theoretical and empirical work.Front Psychol. 2015;6:368. doi:10.3389/fpsyg.2015.00368Young T.II. The Bakerian Lecture. On the theory of light and colours.Philosophical Transactions of the Royal Society of London.1802;92:12-48. doi:10.1098/rstl.1802.0004Helmholtz H von.Helmholtz’s Treatise on Physiological Optics. 3rdEd. Southall JPC, trans. Thoemmes Press; 2000.Jordan G, Deeb SS, Bosten JM, Mollon JD.The dimensionality of color vision in carriers of anomalous trichromacy.Journal of Vision. 2010;10(8):12. doi:10.1167/10.8.12American Academy of Ophthalmology.What is color blindness?Shevell SK, Martin PR.Color opponency: Tutorial.J Opt Soc Am A Opt Image Sci Vis. 2017;34(7):1099–1108. doi:10.1364/JOSAA.34.001099

9 Sources

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Lee BB.The evolution of concepts of color vision.Neurociencias. 2008;4(4):209–224.Neitz J, Carroll J, Neitz M.Color vision: Almost reason enough for having eyes.Optics and Photonics News. 2001;12(1):26-33. doi:10.1364/OPN.12.1.000026Piqueras-Fiszman B, Spence C.Colour, pleasantness, and consumption behaviour within a meal.Appetite. 2014;75:165-172. doi:10.1016/j.appet.2014.01.004Elliot AJ.Color and psychological functioning: A review of theoretical and empirical work.Front Psychol. 2015;6:368. doi:10.3389/fpsyg.2015.00368Young T.II. The Bakerian Lecture. On the theory of light and colours.Philosophical Transactions of the Royal Society of London.1802;92:12-48. doi:10.1098/rstl.1802.0004Helmholtz H von.Helmholtz’s Treatise on Physiological Optics. 3rdEd. Southall JPC, trans. Thoemmes Press; 2000.Jordan G, Deeb SS, Bosten JM, Mollon JD.The dimensionality of color vision in carriers of anomalous trichromacy.Journal of Vision. 2010;10(8):12. doi:10.1167/10.8.12American Academy of Ophthalmology.What is color blindness?Shevell SK, Martin PR.Color opponency: Tutorial.J Opt Soc Am A Opt Image Sci Vis. 2017;34(7):1099–1108. doi:10.1364/JOSAA.34.001099

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Lee BB.The evolution of concepts of color vision.Neurociencias. 2008;4(4):209–224.Neitz J, Carroll J, Neitz M.Color vision: Almost reason enough for having eyes.Optics and Photonics News. 2001;12(1):26-33. doi:10.1364/OPN.12.1.000026Piqueras-Fiszman B, Spence C.Colour, pleasantness, and consumption behaviour within a meal.Appetite. 2014;75:165-172. doi:10.1016/j.appet.2014.01.004Elliot AJ.Color and psychological functioning: A review of theoretical and empirical work.Front Psychol. 2015;6:368. doi:10.3389/fpsyg.2015.00368Young T.II. The Bakerian Lecture. On the theory of light and colours.Philosophical Transactions of the Royal Society of London.1802;92:12-48. doi:10.1098/rstl.1802.0004Helmholtz H von.Helmholtz’s Treatise on Physiological Optics. 3rdEd. Southall JPC, trans. Thoemmes Press; 2000.Jordan G, Deeb SS, Bosten JM, Mollon JD.The dimensionality of color vision in carriers of anomalous trichromacy.Journal of Vision. 2010;10(8):12. doi:10.1167/10.8.12American Academy of Ophthalmology.What is color blindness?Shevell SK, Martin PR.Color opponency: Tutorial.J Opt Soc Am A Opt Image Sci Vis. 2017;34(7):1099–1108. doi:10.1364/JOSAA.34.001099

Lee BB.The evolution of concepts of color vision.Neurociencias. 2008;4(4):209–224.

Neitz J, Carroll J, Neitz M.Color vision: Almost reason enough for having eyes.Optics and Photonics News. 2001;12(1):26-33. doi:10.1364/OPN.12.1.000026

Piqueras-Fiszman B, Spence C.Colour, pleasantness, and consumption behaviour within a meal.Appetite. 2014;75:165-172. doi:10.1016/j.appet.2014.01.004

Elliot AJ.Color and psychological functioning: A review of theoretical and empirical work.Front Psychol. 2015;6:368. doi:10.3389/fpsyg.2015.00368

Young T.II. The Bakerian Lecture. On the theory of light and colours.Philosophical Transactions of the Royal Society of London.1802;92:12-48. doi:10.1098/rstl.1802.0004

Helmholtz H von.Helmholtz’s Treatise on Physiological Optics. 3rdEd. Southall JPC, trans. Thoemmes Press; 2000.

Jordan G, Deeb SS, Bosten JM, Mollon JD.The dimensionality of color vision in carriers of anomalous trichromacy.Journal of Vision. 2010;10(8):12. doi:10.1167/10.8.12

American Academy of Ophthalmology.What is color blindness?

Shevell SK, Martin PR.Color opponency: Tutorial.J Opt Soc Am A Opt Image Sci Vis. 2017;34(7):1099–1108. doi:10.1364/JOSAA.34.001099

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