Blog

Color (or colour in Commonwealth English; see spelling differences) is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object’s light absorption, reflection, emission spectra, and interference. For most humans, colors are perceived in the visible light spectrum with three types of cone cells (trichromacy). Other animals may have a different number of cone cell types or have eyes sensitive to different wavelengths, such as bees that can distinguish ultraviolet, and thus have a different color sensitivity range. Animal perception of color originates from different light wavelength or spectral sensitivity in cone cell types, which is then processed by the brain.

Colored pencils

Colors have perceived properties such as hue, colorfulness (saturation), and luminance. Colors can also be additively mixed (commonly used for actual light) or subtractively mixed (commonly used for materials). If the colors are mixed in the right proportions, because of metamerism, they may look the same as a single-wavelength light. For convenience, colors can be organized in a color space, which when being abstracted as a mathematical color model can assign each region of color with a corresponding set of numbers. As such, color spaces are an essential tool for color reproduction in print, photography, computer monitors, and television. Some of the most well-known color models and color spaces are RGB, CMYK, HSL/HSV, CIE Lab, and YCbCr/YUV.

Because the perception of color is an important aspect of human life, different colors have been associated with emotions, activity, and nationality. Names of color regions in different cultures can have different, sometimes overlapping areas. In visual arts, color theory is used to govern the use of colors in an aesthetically pleasing and harmonious way. The theory of color includes the color complements; color balance; and classification of primary colors (traditionally red, yellow, blue), secondary colors (traditionally orange, green, purple), and tertiary colors. The study of colors in general is called color science.

Physical properties

Electromagnetic radiation is characterized by its wavelength (or frequency) and its intensity. When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 390 nm to 700 nm), it is known as “visible light“.^[1]

Most light sources emit light at many different wavelengths; a source’s spectrum is a distribution giving its intensity at each wavelength. Although the spectrum of light arriving at the eye from a given direction determines the color sensation in that direction, there are many more possible spectral combinations than color sensations. In fact, one may formally define a color as a class of spectra that give rise to the same color sensation, although such classes would vary widely among different species, and to a lesser extent among individuals within the same species. In each such class, the members are called metamers of the color in question. This effect can be visualized by comparing the light sources’ spectral power distributions and the resulting colors.

Spectral colors

Main article: Spectral color

The familiar colors of the rainbow in the spectrum—named using the Latin word for appearance or apparition by Isaac Newton in 1671—include all those colors that can be produced by visible light of a single wavelength only, the pure spectral or monochromatic colors. The spectrum above shows approximate wavelengths (in nm) for spectral colors in the visible range. Spectral colors have 100% purity, and are fully saturated. A complex mixture of spectral colors can be used to describe any color, which is the definition of a light power spectrum.

The spectral colors form a continuous spectrum, and how it is divided into distinct colors linguistically is a matter of culture and historical contingency.^[2] Despite the ubiquitous ROYGBIV mnemonic used to remember the spectral colors in English, the inclusion or exclusion of colors is contentious, with disagreement often focused on indigo and cyan.^[3] Even if the subset of color terms is agreed, their wavelength ranges and borders between them may not be.

The intensity of a spectral color, relative to the context in which it is viewed, may alter its perception considerably. For example, a low-intensity orange-yellow is brown, and a low-intensity yellow-green is olive green. Additionally, hue shifts towards yellow or blue happen if the intensity of a spectral light is increased; this is called Bezold–Brücke shift. In color models capable of representing spectral colors,^[4] such as CIELUV, a spectral color has the maximal saturation. In Helmholtz coordinates, this is described as 100% purity.

Color of objects

The physical color of an object depends on how it absorbs and scatters light. Most objects scatter light to some degree and do not reflect or transmit light specularly like glasses or mirrors. A transparent object allows almost all light to transmit or pass through, thus transparent objects are perceived as colorless. Conversely, an opaque object does not allow light to transmit through and instead absorbs or reflects the light it receives. Like transparent objects, translucent objects allow light to transmit through, but translucent objects are seen colored because they scatter or absorb certain wavelengths of light via internal scattering. The absorbed light is often dissipated as heat.^[5]

Color vision

Main article: Color vision

Development of theories of color vision

Main article: Color theory

Although Aristotle and other ancient scientists had already written on the nature of light and color vision, it was not until Newton that light was identified as the source of the color sensation. In 1810, Goethe published his comprehensive Theory of Colors in which he provided a rational description of color experience, which ‘tells us how it originates, not what it is’. (Schopenhauer)

In 1801 Thomas Young proposed his trichromatic theory, based on the observation that any color could be matched with a combination of three lights. This theory was later refined by James Clerk Maxwell and Hermann von Helmholtz. As Helmholtz puts it, “the principles of Newton’s law of mixture were experimentally confirmed by Maxwell in 1856. Young’s theory of color sensations, like so much else that this marvelous investigator achieved in advance of his time, remained unnoticed until Maxwell directed attention to it.”^[6]

At the same time as Helmholtz, Ewald Hering developed the opponent process theory of color, noting that color blindness and afterimages typically come in opponent pairs (red-green, blue-orange, yellow-violet, and black-white). Ultimately these two theories were synthesized in 1957 by Hurvich and Jameson, who showed that retinal processing corresponds to the trichromatic theory, while processing at the level of the lateral geniculate nucleus corresponds to the opponent theory.^[7]

In 1931, an international group of experts known as the Commission internationale de l’éclairage (CIE) developed a mathematical color model, which mapped out the space of observable colors and assigned a set of three numbers to each.

Color in the eye

Main article: Color vision § Cone cells in the human eye

The ability of the human eye to distinguish colors is based upon the varying sensitivity of different cells in the retina to light of different wavelengths. Humans are trichromatic—the retina contains three types of color receptor cells, or cones. One type, relatively distinct from the other two, is most responsive to light that is perceived as blue or blue-violet, with wavelengths around 450 nm; cones of this type are sometimes called short-wavelength cones or S cones (or misleadingly, blue cones). The other two types are closely related genetically and chemically: middle-wavelength cones, M cones, or green cones are most sensitive to light perceived as green, with wavelengths around 540 nm, while the long-wavelength cones, L cones, or red cones, are most sensitive to light that is perceived as greenish yellow, with wavelengths around 570 nm.

Light, no matter how complex its composition of wavelengths, is reduced to three color components by the eye. Each cone type adheres to the principle of univariance, which is that each cone’s output is determined by the amount of light that falls on it over all wavelengths. For each location in the visual field, the three types of cones yield three signals based on the extent to which each is stimulated. These amounts of stimulation are sometimes called tristimulus values.^[8]

The response curve as a function of wavelength varies for each type of cone. Because the curves overlap, some tristimulus values do not occur for any incoming light combination. For example, it is not possible to stimulate only the mid-wavelength (so-called “green”) cones; the other cones will inevitably be stimulated to some degree at the same time. The set of all possible tristimulus values determines the human color space. It has been estimated that humans can distinguish roughly 10 million different colors.^[9]

The other type of light-sensitive cell in the eye, the rod, has a different response curve. In normal situations, when light is bright enough to strongly stimulate the cones, rods play virtually no role in vision at all.^[10] On the other hand, in dim light, the cones are understimulated leaving only the signal from the rods, resulting in a colorless response (furthermore, the rods are barely sensitive to light in the “red” range). In certain conditions of intermediate illumination, the rod response and a weak cone response can together result in color discriminations not accounted for by cone responses alone. These effects, combined, are summarized also in the Kruithof curve, which describes the change of color perception and pleasingness of light as a function of temperature and intensity.

Color in the brain

Main article: Color vision § Color in the primate brain

While the mechanisms of color vision at the level of the retina are well-described in terms of tristimulus values, color processing after that point is organized differently. A dominant theory of color vision proposes that color information is transmitted out of the eye by three opponent processes, or opponent channels, each constructed from the raw output of the cones: a red–green channel, a blue–yellow channel, and a black–white “luminance” channel. This theory has been supported by neurobiology, and accounts for the structure of our subjective color experience. Specifically, it explains why humans cannot perceive a “reddish green” or “yellowish blue”, and it predicts the color wheel: it is the collection of colors for which at least one of the two color channels measures a value at one of its extremes.

The exact nature of color perception beyond the processing already described, and indeed the status of color as a feature of the perceived world or rather as a feature of our perception of the world—a type of qualia—is a matter of complex and continuing philosophical dispute.^{[citation needed]}

From the V1 blobs, color information is sent to cells in the second visual area, V2. The cells in V2 that are most strongly color tuned are clustered in the “thin stripes” that, like the blobs in V1, stain for the enzyme cytochrome oxidase (separating the thin stripes are interstripes and thick stripes, which seem to be concerned with other visual information like motion and high-resolution form). Neurons in V2 then synapse onto cells in the extended V4. This area includes not only V4, but two other areas in the posterior inferior temporal cortex, anterior to area V3, the dorsal posterior inferior temporal cortex, and posterior TEO.^[11][12] Area V4 was initially suggested by Semir Zeki to be exclusively dedicated to color,^[13] and he later showed that V4 can be subdivided into subregions with very high concentrations of color cells separated from each other by zones with lower concentration of such cells though even the latter cells respond better to some wavelengths than to others,^[14] a finding confirmed by subsequent studies.^[11][15][16] The presence in V4 of orientation-selective cells led to the view that V4 is involved in processing both color and form associated with color^[17] but it is worth noting that the orientation selective cells within V4 are more broadly tuned than their counterparts in V1, V2, and V3.^[14] Color processing in the extended V4 occurs in millimeter-sized color modules called globs.^[11][12] This is the part of the brain in which color is first processed into the full range of hues found in color space.^[18][11][12]

Nonstandard color perception

Color vision deficiency

Main article: Color blindness

A color vision deficiency causes an individual to perceive a smaller gamut of colors than the standard observer with normal color vision. The effect can be mild, having lower “color resolution” (i.e. anomalous trichromacy), moderate, lacking an entire dimension or channel of color (e.g. dichromacy), or complete, lacking all color perception (i.e. monochromacy). Most forms of color blindness derive from one or more of the three classes of cone cells either being missing, having a shifted spectral sensitivity or having lower responsiveness to incoming light. In addition, cerebral achromatopsia is caused by neural anomalies in those parts of the brain where visual processing takes place.

Some colors that appear distinct to an individual with normal color vision will appear metameric to the color blind. The most common form of color blindness is congenital red–green color blindness, affecting ~8% of males. Individuals with the strongest form of this condition (dichromacy) will experience blue and purple, green and yellow, teal, and gray as colors of confusion, i.e. metamers.^[19]

Tetrachromacy

Main article: Tetrachromacy

Outside of humans, which are mostly trichromatic (having three types of cones), most mammals are dichromatic, possessing only two cones. However, outside of mammals, most vertebrates are tetrachromatic, having four types of cones. This includes most birds,^[20][21][22] reptiles, amphibians, and bony fish.^[23][24] An extra dimension of color vision means these vertebrates can see two distinct colors that a normal human would view as metamers. Some invertebrates, such as the mantis shrimp, have an even higher number of cones (12) that could lead to a richer color gamut than even imaginable by humans.

The existence of human tetrachromats is a contentious notion. As many as half of all human females have 4 distinct cone classes, which could enable tetrachromacy.^[25] However, a distinction must be made between retinal (or weak) tetrachromats, which express four cone classes in the retina, and functional (or strong) tetrachromats, which are able to make the enhanced color discriminations expected of tetrachromats. In fact, there is only one peer-reviewed report of a functional tetrachromat.^[26] It is estimated that while the average person is able to see one million colors, someone with functional tetrachromacy could see a hundred million colors.^[27]

Synesthesia

Main article: Synesthesia

In certain forms of synesthesia, perceiving letters and numbers (grapheme–color synesthesia) or hearing sounds (chromesthesia) will evoke a perception of color. Behavioral and functional neuroimaging experiments have demonstrated that these color experiences lead to changes in behavioral tasks and lead to increased activation of brain regions involved in color perception, thus demonstrating their reality, and similarity to real color percepts, albeit evoked through a non-standard route. Synesthesia can occur genetically, with 4% of the population having variants associated with the condition. Synesthesia has also been known to occur with brain damage, drugs, and sensory deprivation.^[28]

The philosopher Pythagoras experienced synesthesia and provided one of the first written accounts of the condition in approximately 550 BCE. He created mathematical equations for musical notes that could form part of a scale, such as an octave.^[29]

Afterimages

Main article: Afterimage

After exposure to strong light in their sensitivity range, photoreceptors of a given type become desensitized.^[30][31] For a few seconds after the light ceases, they will continue to signal less strongly than they otherwise would. Colors observed during that period will appear to lack the color component detected by the desensitized photoreceptors. This effect is responsible for the phenomenon of afterimages, in which the eye may continue to see a bright figure after looking away from it, but in a complementary color. Afterimage effects have also been used by artists, including Vincent van Gogh.

Color constancy

Main article: Color constancy

When an artist uses a limited color palette, the human visual system tends to compensate by seeing any gray or neutral color as the color which is missing from the color wheel. For example, in a limited palette consisting of red, yellow, black, and white, a mixture of yellow and black will appear as a variety of green, a mixture of red and black will appear as a variety of purple, and pure gray will appear bluish.^[32]

The trichromatic theory is strictly true when the visual system is in a fixed state of adaptation.^[33] In reality, the visual system is constantly adapting to changes in the environment and compares the various colors in a scene to reduce the effects of the illumination. If a scene is illuminated with one light, and then with another, as long as the difference between the light sources stays within a reasonable range, the colors in the scene appear relatively constant to us. This was studied by Edwin H. Land in the 1970s and led to his retinex theory of color constancy.^[34][35]

Both phenomena are readily explained and mathematically modeled with modern theories of chromatic adaptation and color appearance (e.g. CIECAM02, iCAM).^[36] There is no need to dismiss the trichromatic theory of vision, but rather it can be enhanced with an understanding of how the visual system adapts to changes in the viewing environment.

Reproduction

Main article: Color reproduction

Color reproduction is the science of creating colors for the human eye that faithfully represent the desired color. It focuses on how to construct a spectrum of wavelengths that will best evoke a certain color in an observer. Most colors are not spectral colors, meaning they are mixtures of various wavelengths of light. However, these non-spectral colors are often described by their dominant wavelength, which identifies the single wavelength of light that produces a sensation most similar to the non-spectral color. Dominant wavelength is roughly akin to hue.

There are many color perceptions that by definition cannot be pure spectral colors due to desaturation or because they are purples (mixtures of red and violet light, from opposite ends of the spectrum). Some examples of necessarily non-spectral colors are the achromatic colors (black, gray, and white) and colors such as pink, tan, and magenta.

Two different light spectra that have the same effect on the three color receptors in the human eye will be perceived as the same color. They are metamers of that color. This is exemplified by the white light emitted by fluorescent lamps, which typically has a spectrum of a few narrow bands, while daylight has a continuous spectrum. The human eye cannot tell the difference between such light spectra just by looking into the light source, although the color rendering index of each light source may affect the color of objects illuminated by these metameric light sources.

Similarly, most human color perceptions can be generated by a mixture of three colors called primaries. This is used to reproduce color scenes in photography, printing, television, and other media. There are a number of methods or color spaces for specifying a color in terms of three particular primary colors. Each method has its advantages and disadvantages depending on the particular application.

No mixture of colors, however, can produce a response truly identical to that of a spectral color, although one can get close, especially for the longer wavelengths, where the CIE 1931 color space chromaticity diagram has a nearly straight edge. For example, mixing green light (530 nm) and blue light (460 nm) produces cyan light that is slightly desaturated, because response of the red color receptor would be greater to the green and blue light in the mixture than it would be to a pure cyan light at 485 nm that has the same intensity as the mixture of blue and green.

Because of this, and because the primaries in color printing systems generally are not pure themselves, the colors reproduced are never perfectly saturated spectral colors, and so spectral colors cannot be matched exactly. However, natural scenes rarely contain fully saturated colors, thus such scenes can usually be approximated well by these systems. The range of colors that can be reproduced with a given color reproduction system is called the gamut. The CIE chromaticity diagram can be used to describe the gamut.

Another problem with color reproduction systems is connected with the initial measurement of color, or colorimetry. The characteristics of the color sensors in measurement devices (e.g. cameras, scanners) are often very far from the characteristics of the receptors in the human eye.

A color reproduction system “tuned” to a human with normal color vision may give very inaccurate results for other observers, according to color vision deviations to the standard observer.

The different color response of different devices can be problematic if not properly managed. For color information stored and transferred in digital form, color management techniques, such as those based on ICC profiles, can help to avoid distortions of the reproduced colors. Color management does not circumvent the gamut limitations of particular output devices, but can assist in finding good mapping of input colors into the gamut that can be reproduced.

Additive coloring

Additive color is light created by mixing together light of two or more different colors.^[37][38] Red, green, and blue are the additive primary colors normally used in additive color systems such as projectors, televisions, and computer terminals.

Subtractive coloring

Subtractive coloring uses dyes, inks, pigments, or filters to absorb some wavelengths of light and not others.^[39] The color that a surface displays comes from the parts of the visible spectrum that are not absorbed and therefore remain visible. Without pigments or dye, fabric fibers, paint base and paper are usually made of particles that scatter white light (all colors) well in all directions. When a pigment or ink is added, wavelengths are absorbed or “subtracted” from white light, so light of another color reaches the eye.

If the light is not a pure white source (the case of nearly all forms of artificial lighting), the resulting spectrum will appear a slightly different color. Red paint, viewed under blue light, may appear black. Red paint is red because it scatters only the red components of the spectrum. If red paint is illuminated by blue light, it will be absorbed by the red paint, creating the appearance of a black object.

The subtractive model also predicts the color resulting from a mixture of paints, or similar medium such as fabric dye, whether applied in layers or mixed together prior to application. In the case of paint mixed before application, incident light interacts with many different pigment particles at various depths inside the paint layer before emerging.^[40]

Structural color

Further information: Structural coloration and Animal coloration

Structural colors are colors caused by interference effects rather than by pigments. Color effects are produced when a material is scored with fine parallel lines, formed of one or more parallel thin layers, or otherwise composed of microstructures on the scale of the color’s wavelength. If the microstructures are spaced randomly, light of shorter wavelengths will be scattered preferentially to produce Tyndall effect colors: the blue of the sky (Rayleigh scattering, caused by structures much smaller than the wavelength of light, in this case, air molecules), the luster of opals, and the blue of human irises. If the microstructures are aligned in arrays, for example, the array of pits in a CD, they behave as a diffraction grating: the grating reflects different wavelengths in different directions due to interference phenomena, separating mixed “white” light into light of different wavelengths. If the structure is one or more thin layers then it will reflect some wavelengths and transmit others, depending on the layers’ thickness.

Structural color is studied in the field of thin-film optics. The most ordered or the most changeable structural colors are iridescent. Structural color is responsible for the blues and greens of the feathers of many birds (the blue jay, for example), as well as certain butterfly wings and beetle shells. Variations in the pattern’s spacing often give rise to an iridescent effect, as seen in peacock feathers, soap bubbles, films of oil, and mother of pearl, because the reflected color depends upon the viewing angle. Numerous scientists have carried out research in butterfly wings and beetle shells, including Isaac Newton and Robert Hooke. Since 1942, electron micrography has been used, advancing the development of products that exploit structural color, such as “photonic” cosmetics.^[41]

Optimal colors

Main article: Gamut § Surfaces (optimal colors)

Optimal colors are the most chromatic colors that surfaces can have. That is, optimal colors are the theoretical limit for the color of objects*. ^[42] For now, we are unable to produce objects with such colors, at least not without recurring to more complex physical phenomena.

*(with classical reflection. Phenomena like fluorescence or structural color may produce objects whose color lies outside the optimal color solid)

The plot of the gamut bounded by optimal colors in a color space is called the optimal color solid or Rösch–MacAdam color solid.

The reflectance spectrum of a color is the amount of light of each wavelength that it reflects, in proportion to a given maximum, which is total reflection of light of that wavelength, and has the value of 1 (100%). If the reflectance spectrum of a color is 0 (0%) or 1 (100%) across the entire visible spectrum, and it has no more than two transitions between 0 and 1, or 1 and 0, then it is an optimal color. With the current state of technology, we are unable to produce any material or pigment with these properties.^[43]

Thus four types of “optimal color” spectra are possible:

• The transition goes from zero at both ends of the spectrum to one in the middle, as shown in the image at right.
• It goes from one at the ends to zero in the middle.
• It goes from 1 at the start of the visible spectrum to 0 in some point in the middle until its end.
• It goes from 0 at the start of the visible spectrum to 1 at some point in the middle until its end.

The first type produces colors that are similar to the spectral colors and follow roughly the horseshoe-shaped portion of the CIE xy chromaticity diagram (the spectral locus), but are, in surfaces, more chromatic, although less spectrally pure. The second type produces colors that are similar to (but, in surfaces, more chromatic and less spectrally pure than) the colors on the straight line in the CIE xy chromaticity diagram (the line of purples), leading to magenta or purple-like colors. The third type produces the colors located in the “warm” sharp edge of the optimal color solid (this will be explained later in the article). The fourth type produces the colors located in the “cold” sharp edge of the optimal color solid.

In optimal color solids, the colors of the visible spectrum are theoretically black, because their reflectance spectrum is 1 (100%) in only one wavelength, and 0 in all of the other infinite visible wavelengths that there are, meaning that they have a lightness of 0 with respect to white, and will also have 0 chroma, but, of course, 100% of spectral purity. In short: In optimal color solids, spectral colors are equivalent to black (0 lightness, 0 chroma), but have full spectral purity (they are located in the horseshoe-shaped spectral locus of the chromaticiy diagram).^[44]

In linear color spaces that contain all colors visible by humans, such as LMS or CIE 1931 XYZ, the set of half-lines that start at the origin (black, (0, 0, 0)) and pass through all the points that represent the colors of the visible spectrum, and the portion of a plane that passes through the violet half-line and the red half-line (both ends of the visible spectrum), generate the “spectrum cone”. The black point (coordinates (0, 0, 0)) of the optimal color solid (and only the black point) is tangent to the “spectrum cone”, and the white point ((1, 1, 1)) (only the white point) is tangent to the “inverted spectrum cone”, with the “inverted spectrum cone” being symmetrical to the “spectrum cone” with respect to the middle gray point ((0.5, 0.5, 0.5)). This means that, in linear color spaces, the optimal color solid is centrally symmetric.^[44]Duration: 8 seconds.0:08Optimal color solid or Rösch–MacAdam color solid (with D65white point) plotted within CIE 1931 XYZ color space. Notice the central symmetry of the solid, and the two sharp edges, one with warm colors and the other one with cold colors.

In most color spaces, the surface of the optimal color solid is smooth, except for two points (black and white); and two sharp edges: the “warm” edge, which goes from black, to red, to orange, to yellow, to white; and the “cold” edge, which goes from black, to deep violet, to blue, to cyan, to white. This is due to the following: If the portion of the reflectance spectrum of a color is spectral red (which is located at one end of the spectrum), it will be seen as black. If the size of the portion of total reflectance is increased, now covering from the red end of the spectrum to the yellow wavelengths, it will be seen as red or orange. If the portion is expanded even more, covering some green wavelengths, it will be seen as yellow. If it is expanded even more, it will cover more wavelengths than the yellow semichrome does, approaching white, until it is reached when the full spectrum is reflected. The described process is called “cumulation”. Cumulation can be started at either end of the visible spectrum (we just described cumulation starting from the red end of the spectrum, generating the “warm” sharp edge), cumulation starting at the violet end of the spectrum will generate the “cold” sharp edge.^[44]Duration: 8 seconds.0:08Optimal color solid plotted within the CIE L* u* v* color space, with D65white point. Notice that it has two sharp edges, one with warm colors, and the other one with cold colors.

On modern computers, it is possible to calculate an optimal color solid with great precision in seconds. Usually, only the MacAdam limits (the optimal colors, the boundary of the Optimal color solid) are computed, because all the other (non-optimal) possible surface colors exist inside the boundary.

Maximum chroma colors, semichromes, or full colors

Each hue has a maximum chroma point, semichrome, or full color; objects cannot have a color of that hue with a higher chroma. They are the most chromatic, vibrant colors that objects can have. They were called semichromes or full colors by the German chemist and philosopher Wilhelm Ostwald in the early 20th century.^[44][45]

If B is the complementary wavelength of wavelength A, then the straight line that connects A and B passes through the achromatic axis in a linear color space, such as LMS or CIE 1931 XYZ. If the reflectance spectrum of a color is 1 (100%) for all the wavelengths between A and B, and 0 for all the wavelengths of the other half of the color space, then that color is a maximum chroma color, semichrome, or full color (this is the explanation to why they were called semichromes). Thus, maximum chroma colors are a type of optimal color.^[44][45]

As explained, full colors are far from being monochromatic (physically, not perceptually). If the spectral purity of a semichrome is increased, its chroma decreases, because it will approach the visible spectrum, ergo, it will approach black.^[44]

In perceptually uniform color spaces, the lightness of the full colors varies from around 30% in the violetish blue hues, to around 90% in the yellowish hues. The chroma of each maximum chroma point also varies depending on the hue; in optimal color solids plotted in perceptually uniform color spaces, semichromes like red, green, violet, and magenta have a high chroma, while semichromes like yellow, orange, and cyan have a slightly lower chroma.

Cultural perspective

The meanings and associations of colors can play a major role in works of art, including literature.^[46]

Associations

Individual colors have a variety of cultural associations such as national colors (in general described in individual color articles and color symbolism). The field of color psychology attempts to identify the effects of color on human emotion and activity. Chromotherapy is a form of alternative medicine attributed to various Eastern traditions. Colors have different associations in different countries and cultures.^[47]

Different colors have been demonstrated to have effects on cognition. For example, researchers at the University of Linz in Austria demonstrated that the color red significantly decreases cognitive functioning in men.^[48] The combination of the colors red and yellow together can induce hunger, which has been capitalized on by a number of chain restaurants.^[49]

Color plays a role in memory development too. A photograph that is in black and white is slightly less memorable than one in color.^[50] Studies also show that wearing bright colors makes one more memorable to people they meet.

Terminology

Main article: Color term

See also: Lists of colors and Web colors

Colors vary in several different ways, including hue (shades of red, orange, yellow, green, blue, and violet, etc.), saturation, brightness. Some color words are derived from the name of an object of that color, such as “orange” or “salmon“, while others are abstract, like “red”.

In the 1969 study Basic Color Terms: Their Universality and Evolution, Brent Berlin and Paul Kay describe a pattern in naming “basic” colors (like “red” but not “red-orange” or “dark red” or “blood red”, which are “shades” of red). All languages that have two “basic” color names distinguish dark/cool colors from bright/warm colors. The next colors to be distinguished are usually red and then yellow or green. All languages with six “basic” colors include black, white, red, green, blue, and yellow. The pattern holds up to a set of twelve: black, gray, white, pink, red, orange, yellow, green, blue, purple, brown, and azure (distinct from blue in Russian and Italian, but not English).

Beauty is commonly described as a feature of objects that makes them pleasurable to perceive. Such objects include landscapes, sunsets, humans and works of art. Beauty, art and taste are the main subjects of aesthetics, one of the fields of study within philosophy. As a positive aesthetic value, it is contrasted with ugliness as its negative counterpart.

One difficulty in understanding beauty is that it has both objective and subjective aspects: it is seen as a property of things but also as depending on the emotional response of observers. Because of its subjective side, beauty is said to be “in the eye of the beholder”.^[2] It has been argued that the ability on the side of the subject needed to perceive and judge beauty, sometimes referred to as the “sense of taste”, can be trained and that the verdicts of experts coincide in the long run. This suggests the standards of validity of judgments of beauty are intersubjective, i.e. dependent on a group of judges, rather than fully subjective or objective.

Conceptions of beauty aim to capture what is essential to all beautiful things. Classical conceptions define beauty in terms of the relation between the beautiful object as a whole and its parts: the parts should stand in the right proportion to each other and thus compose an integrated harmonious whole. Hedonist conceptions see a necessary connection between pleasure and beauty, e.g. that for an object to be beautiful is for it to cause disinterested pleasure. Other conceptions include defining beautiful objects in terms of their value, of a loving attitude toward them or of their function.

A Rayonnant style rose window in Notre-Dame de Paris. In Gothic architecture, light was considered “the source and actual essence of all that is beautiful”.^[1]

Overview

Beauty, together with art and taste, is the main subject of aesthetics, one of the major branches of philosophy.^[3][4] Beauty is usually categorized as an aesthetic property besides other properties, like grace, elegance or the sublime.^[5][6][7] As a positive aesthetic value, beauty is contrasted with ugliness as its negative counterpart. Beauty is often listed as one of the three fundamental concepts of human understanding besides truth and goodness.^[5][8][6]

Objectivists or realists see beauty as an objective or mind-independent feature of beautiful things, which is denied by subjectivists.^[3][9] The source of this debate is that judgments of beauty seem to be based on subjective grounds, namely our feelings, while claiming universal correctness at the same time.^[10] This tension is sometimes referred to as the “antinomy of taste”.^[4] Adherents of both sides have suggested that a certain faculty, commonly called a sense of taste, is necessary for making reliable judgments about beauty.^[3][10] David Hume, for example, suggests that this faculty can be trained and that the verdicts of experts coincide in the long run.^[3][9]

Beauty is mainly discussed in relation to concrete objects accessible to sensory perception. It has been suggested that the beauty of a thing supervenes on the sensory features of this thing.^[10] It has also been proposed that abstract objects like stories or mathematical proofs can be beautiful.^[11] Beauty plays a central role in works of art and nature.^[12][10]

An influential distinction among beautiful things, according to Immanuel Kant, is that between adherent beauty (pulchritudo adhaerens)^{[note 1]} and free beauty (pulchritudo vaga). A thing has adherent beauty if its beauty depends on the conception or function of this thing, unlike free or absolute beauty.^[10] Examples of adherent beauty include an ox which is beautiful as an ox but not beautiful as a horse^[3] or a photograph which is beautiful, because it depicts a beautiful building but that lacks beauty generally speaking because of its low quality.^[9]

Objectivism and subjectivism

Further information: objectivity and subjectivity

Judgments of beauty seem to occupy an intermediary position between objective judgments, e.g. concerning the mass and shape of a grapefruit, and subjective likes, e.g. concerning whether the grapefruit tastes good.^[13][10][9] Judgments of beauty differ from the former because they are based on subjective feelings rather than objective perception. But they also differ from the latter because they lay claim on universal correctness.^[10] This tension is also reflected in common language. On the one hand, we talk about beauty as an objective feature of the world that is ascribed, for example, to landscapes, paintings or humans.^[14] The subjective side, on the other hand, is expressed in sayings like “beauty is in the eye of the beholder”.^[3]

These two positions are often referred to as objectivism (or realism) and subjectivism.^[3] Objectivism is the traditional view, while subjectivism developed more recently in western philosophy. Objectivists hold that beauty is a mind-independent feature of things. On this account, the beauty of a landscape is independent of who perceives it or whether it is perceived at all.^[3][9] Disagreements may be explained by an inability to perceive this feature, sometimes referred to as a “lack of taste”.^[15] Subjectivism, on the other hand, denies the mind-independent existence of beauty.^[5][3][9] Influential for the development of this position was John Locke‘s distinction between primary qualities, which the object has independent of the observer, and secondary qualities, which constitute powers in the object to produce certain ideas in the observer.^[3][16][5] When applied to beauty, there is still a sense in which it depends on the object and its powers.^[9] But this account makes the possibility of genuine disagreements about claims of beauty implausible, since the same object may produce very different ideas in distinct observers. The notion of “taste” can still be used to explain why different people disagree about what is beautiful, but there is no objectively right or wrong taste, there are just different tastes.^[3]

The problem with both the objectivist and the subjectivist position in their extreme form is that each has to deny some intuitions about beauty. This issue is sometimes discussed under the label “antinomy of taste”.^[3][4] It has prompted various philosophers to seek a unified theory that can take all these intuitions into account. One promising route to solve this problem is to move from subjective to intersubjective theories, which hold that the standards of validity of judgments of taste are intersubjective or dependent on a group of judges rather than objective. This approach tries to explain how genuine disagreement about beauty is possible despite the fact that beauty is a mind-dependent property, dependent not on an individual but a group.^[3][4] A closely related theory sees beauty as a secondary or response-dependent property.^[9] On one such account, an object is beautiful “if it causes pleasure by virtue of its aesthetic properties”.^[5] The problem that different people respond differently can be addressed by combining response-dependence theories with so-called ideal-observer theories: it only matters how an ideal observer would respond.^[10] There is no general agreement on how “ideal observers” are to be defined, but it is usually assumed that they are experienced judges of beauty with a fully developed sense of taste. This suggests an indirect way of solving the antinomy of taste: instead of looking for necessary and sufficient conditions of beauty itself, one can learn to identify the qualities of good critics and rely on their judgments.^[3] This approach only works if unanimity among experts was ensured. But even experienced judges may disagree in their judgments, which threatens to undermine ideal-observer theories.^[3][9]

Conceptions

Various conceptions of the essential features of beautiful things have been proposed but there is no consensus as to which is the right one.

Classical

The “classical conception” (see Classicism) defines beauty in terms of the relation between the beautiful object as a whole and its parts: the parts should stand in the right proportion to each other and thus compose an integrated harmonious whole.^[3][5][9] On this account, which found its most explicit articulation in the Italian Renaissance, the beauty of a human body, for example, depends, among other things, on the right proportion of the different parts of the body and on the overall symmetry.^[3] One problem with this conception is that it is difficult to give a general and detailed description of what is meant by “harmony between parts” and raises the suspicion that defining beauty through harmony results in exchanging one unclear term for another one.^[3] Some attempts have been made to dissolve this suspicion by searching for laws of beauty, like the golden ratio.

18th century philosopher Alexander Baumgarten, for example, saw laws of beauty in analogy with laws of nature and believed that they could be discovered through empirical research.^[5] As of 2003, these attempts have failed to find a general definition of beauty and several authors take the opposite claim that such laws cannot be formulated, as part of their definition of beauty.^[10]

Hedonism

Main article: Hedonism

A very common element in many conceptions of beauty is its relation to pleasure.^[11][5] Hedonism makes this relation part of the definition of beauty by holding that there is a necessary connection between pleasure and beauty, e.g. that for an object to be beautiful is for it to cause pleasure or that the experience of beauty is always accompanied by pleasure.^[12] This account is sometimes labeled as “aesthetic hedonism” in order to distinguish it from other forms of hedonism.^[17][18] An influential articulation of this position comes from Thomas Aquinas, who treats beauty as “that which pleases in the very apprehension of it”.^[19] Immanuel Kant explains this pleasure through a harmonious interplay between the faculties of understanding and imagination.^[11] A further question for hedonists is how to explain the relation between beauty and pleasure. This problem is akin to the Euthyphro dilemma: is something beautiful because we enjoy it or do we enjoy it because it is beautiful?^[5] Identity theorists solve this problem by denying that there is a difference between beauty and pleasure: they identify beauty, or the appearance of it, with the experience of aesthetic pleasure.^[11]

Hedonists usually restrict and specify the notion of pleasure in various ways in order to avoid obvious counterexamples. One important distinction in this context is the difference between pure and mixed pleasure.^[11] Pure pleasure excludes any form of pain or unpleasant feeling while the experience of mixed pleasure can include unpleasant elements.^[20] But beauty can involve mixed pleasure, for example, in the case of a beautifully tragic story, which is why mixed pleasure is usually allowed in hedonist conceptions of beauty.^[11]

Another problem faced by hedonist theories is that we take pleasure from many things that are not beautiful. One way to address this issue is to associate beauty with a special type of pleasure: aesthetic or disinterested pleasure.^[3][4][7] A pleasure is disinterested if it is indifferent to the existence of the beautiful object or if it did not arise owing to an antecedent desire through means-end reasoning.^[21][11] For example, the joy of looking at a beautiful landscape would still be valuable if it turned out that this experience was an illusion, which would not be true if this joy was due to seeing the landscape as a valuable real estate opportunity.^[3] Opponents of hedonism usually concede that many experiences of beauty are pleasurable but deny that this is true for all cases.^[12] For example, a cold jaded critic may still be a good judge of beauty because of her years of experience but lack the joy that initially accompanied her work.^[11] One way to avoid this objection is to allow responses to beautiful things to lack pleasure while insisting that all beautiful things merit pleasure, that aesthetic pleasure is the only appropriate response to them.^[12]

Others

G. E. Moore explained beauty in regard to intrinsic value as “that of which the admiring contemplation is good in itself”.^[21][5] This definition connects beauty to experience while managing to avoid some of the problems usually associated with subjectivist positions since it allows that things may be beautiful even if they are never experienced.^[21]

Another subjectivist theory of beauty comes from George Santayana, who suggested that we project pleasure onto the things we call “beautiful”. So in a process akin to a category mistake, one treats one’s subjective pleasure as an objective property of the beautiful thing.^[11][3][5] Other conceptions include defining beauty in terms of a loving or longing attitude toward the beautiful object or in terms of its usefulness or function.^[3][22] In 1871, functionalist Charles Darwin explained beauty as result of accumulative sexual selection in “The Descent of Man and Selection in Relation to Sex”.^[5]

In philosophy

Greco-Roman tradition

The classical Greek noun that best translates to the English-language words “beauty” or “beautiful” was κάλλος, kallos, and the adjective was καλός, kalos. This is also translated as “good” or “of fine quality” and thus has a broader meaning than mere physical or material beauty. Similarly, kallos was used differently from the English word beauty in that it first and foremost applied to humans and bore an erotic connotation.^[23] The Koine Greek word for beautiful was ὡραῖος, hōraios,^[24] an adjective etymologically coming from the word ὥρα, hōra, meaning “hour”. In Koine Greek, beauty was thus associated with “being of one’s hour”.^[25] Thus, a ripe fruit (of its time) was considered beautiful, whereas a young woman trying to appear older or an older woman trying to appear younger would not be considered beautiful. In Attic Greek, hōraios had many meanings, including “youthful” and “ripe old age”.^[25] Another classical term in use to describe beauty was pulchrum (Latin).^[26]

Beauty for ancient thinkers existed both in form, which is the material world as it is, and as embodied in the spirit, which is the world of mental formations.^[27] Greek mythology mentions Helen of Troy as the most beautiful woman.^{[28][29][30][31][32]} Ancient Greek architecture is based on this view of symmetry and proportion.

Pre-Socratic

In one fragment of Heraclitus’s writings (Fragment 106) he mentions beauty, this reads: “To God all things are beautiful, good, right…”^[33] The earliest Western theory of beauty can be found in the works of early Greek philosophers from the pre-Socratic period, such as Pythagoras, who conceived of beauty as useful for a moral education of the soul.^[34] He wrote of how people experience pleasure when aware of a certain type of formal situation present in reality, perceivable by sight or through the ear^[35] and discovered the underlying mathematical ratios in the harmonic scales in music.^[34] The Pythagoreans conceived of the presence of beauty in universal terms, which is, as existing in a cosmological state, they observed beauty in the heavens.^[27] They saw a strong connection between mathematics and beauty. In particular, they noted that objects proportioned according to the golden ratio seemed more attractive.^[36]

Classical period

The classical concept of beauty is one that exhibits perfect proportion (Wolfflin).^[37] In this context, the concept belonged often within the discipline of mathematics.^[26] An idea of spiritual beauty emerged during the classical period,^[27] beauty was something embodying divine goodness, while the demonstration of behaviour which might be classified as beautiful, from an inner state of morality which is aligned to the good.^[38]

The writing of Xenophon shows a conversation between Socrates and Aristippus. Socrates discerned differences in the conception of the beautiful, for example, in inanimate objects, the effectiveness of execution of design was a deciding factor on the perception of beauty in something.^[27] By the account of Xenophon, Socrates found beauty congruent with that to which was defined as the morally good, in short, he thought beauty coincident with the good.^[39]

Beauty is a subject of Plato in his work Symposium.^[34] In the work, the high priestess Diotima describes how beauty moves out from a core singular appreciation of the body to outer appreciations via loved ones, to the world in its state of culture and society (Wright).^[35] In other words, Diotoma gives to Socrates an explanation of how love should begin with erotic attachment, and end with the transcending of the physical to an appreciation of beauty as a thing in itself. The ascent of love begins with one’s own body, then secondarily, in appreciating beauty in another’s body, thirdly beauty in the soul, which cognates to beauty in the mind in the modern sense, fourthly beauty in institutions, laws and activities, fifthly beauty in knowledge, the sciences, and finally to lastly love beauty itself, which translates to the original Greek language term as auto to kalon.^[40] In the final state, auto to kalon and truth are united as one.^[41] There is the sense in the text, concerning love and beauty they both co-exist but are still independent or, in other words, mutually exclusive, since love does not have beauty since it seeks beauty.^[42] The work toward the end provides a description of beauty in a negative sense.^[42]

Plato also discusses beauty in his work Phaedrus,^[41] and identifies Alcibiades as beautiful in Parmenides.^[43] He considered beauty to be the Idea (Form) above all other Ideas.^[44] Platonic thought synthesized beauty with the divine.^[35] Scruton (cited: Konstan) states Plato states of the idea of beauty, of it (the idea), being something inviting desirousness (cf. seducing), and, promotes an intellectual renunciation (cf. denouncing) of desire.^[45] For Alexander Nehamas, it is only the locating of desire to which the sense of beauty exists, in the considerations of Plato.^[46]

Aristotle defines beauty in Metaphysics as having order, symmetry and definiteness which the mathematical sciences exhibit to a special degree.^[37] He saw a relationship between the beautiful (to kalon) and virtue, arguing that “Virtue aims at the beautiful.”^[47]

Roman

In De Natura Deorum, Cicero wrote: “the splendour and beauty of creation”, in respect to this, and all the facets of reality resulting from creation, he postulated these to be a reason to see the existence of a God as creator.^[48]

Western Middle Ages

In the Middle Ages, Catholic philosophers like Thomas Aquinas included beauty among the transcendental attributes of being.^[49] In his Summa Theologica, Aquinas described the three conditions of beauty as: integritas (wholeness), consonantia (harmony and proportion), and claritas (a radiance and clarity that makes the form of a thing apparent to the mind).^[50]

In the Gothic Architecture of the High and Late Middle Ages, light was considered the most beautiful revelation of God, which was heralded in design.^[51] Examples are the stained glass of Gothic Cathedrals including Notre-Dame de Paris and Chartres Cathedral.^[52]

St. Augustine said of beauty “Beauty is indeed a good gift of God; but that the good may not think it a great good, God dispenses it even to the wicked.”^[53]

Renaissance

Classical philosophy and sculptures of men and women produced according to the Greek philosophers‘ tenets of ideal human beauty were rediscovered in Renaissance Europe, leading to a re-adoption of what became known as a “classical ideal”. In terms of female human beauty, a woman whose appearance conforms to these tenets is still called a “classical beauty” or said to possess a “classical beauty”, whilst the foundations laid by Greek and Roman artists have also supplied the standard for male beauty and female beauty in western civilization as seen, for example, in the Winged Victory of Samothrace. During the Gothic era, the classical aesthetical canon of beauty was rejected as sinful. Later, Renaissance and Humanist thinkers rejected this view, and considered beauty to be the product of rational order and harmonious proportions. Renaissance artists and architects (such as Giorgio Vasari in his “Lives of Artists”) criticised the Gothic period as irrational and barbarian. This point of view of Gothic art lasted until Romanticism, in the 19th century. Vasari aligned himself to the classical notion and thought of beauty as defined as arising from proportion and order.^[38]

Age of Reason

The Age of Reason saw a rise in an interest in beauty as a philosophical subject. For example, Scottish philosopher Francis Hutcheson argued that beauty is “unity in variety and variety in unity”.^[55] He wrote that beauty was neither purely subjective nor purely objective—it could be understood not as “any Quality suppos’d to be in the Object, which should of itself be beautiful, without relation to any Mind which perceives it: For Beauty, like other Names of sensible Ideas, properly denotes the Perception of some mind; … however we generally imagine that there is something in the Object just like our Perception.”^[56]

Immanuel Kant believed that there could be no “universal criterion of the beautiful” and that the experience of beauty is subjective, but that an object is judged to be beautiful when it seems to display “purposiveness”; that is, when its form is perceived to have the character of a thing designed according to some principle and fitted for a purpose.^[57] He distinguished “free beauty” from “merely adherent beauty”, explaining that “the first presupposes no concept of what the object ought to be; the second does presuppose such a concept and the perfection of the object in accordance therewith.”^[58] By this definition, free beauty is found in seashells and wordless music; adherent beauty in buildings and the human body.^[58]

The Romantic poets, too, became highly concerned with the nature of beauty, with John Keats arguing in Ode on a Grecian Urn that:Beauty is truth, truth beauty, —that is allYe know on earth, and all ye need to know.

Western 19th and 20th century

In the Romantic period, Edmund Burke postulated a difference between beauty in its classical meaning and the sublime.^[59] The concept of the sublime, as explicated by Burke and Kant, suggested viewing Gothic art and architecture, though not in accordance with the classical standard of beauty, as sublime.^[60]

The 20th century saw an increasing rejection of beauty by artists and philosophers alike, culminating in postmodernism‘s anti-aesthetics.^[61] This is despite beauty being a central concern of one of postmodernism’s main influences, Friedrich Nietzsche, who argued that the Will to Power was the Will to Beauty.^[62]

In the aftermath of postmodernism’s rejection of beauty, thinkers have returned to beauty as an important value. American analytic philosopher Guy Sircello proposed his New Theory of Beauty as an effort to reaffirm the status of beauty as an important philosophical concept.^[63][64] He rejected the subjectivism of Kant and sought to identify the properties inherent in an object that make it beautiful. He called qualities such as vividness, boldness, and subtlety “properties of qualitative degree” (PQDs) and stated that a PQD makes an object beautiful if it is not—and does not create the appearance of—”a property of deficiency, lack, or defect”; and if the PQD is strongly present in the object.^[65]

Elaine Scarry argues that beauty is related to justice.^[66]

Beauty is also studied by psychologists and neuroscientists in the field of experimental aesthetics and neuroesthetics respectively. Psychological theories see beauty as a form of pleasure.^[67][68] Correlational findings support the view that more beautiful objects are also more pleasing.^[69][70][71] Some studies suggest that higher experienced beauty is associated with activity in the medial orbitofrontal cortex.^[72][73] This approach of localizing the processing of beauty in one brain region has received criticism within the field.^[74]

Philosopher and novelist Umberto Eco wrote On Beauty: A History of a Western Idea (2004)^[75][76] and On Ugliness (2007).^[77] The narrator of his novel The Name of the Rose follows Aquinas in declaring: “three things concur in creating beauty: first of all integrity or perfection, and for this reason, we consider ugly all incomplete things; then proper proportion or consonance; and finally clarity and light”, before going on to say “the sight of the beautiful implies peace”.^[78][79] Mike Phillips has described Umberto Eco’s On Beauty as “incoherent” and criticized him for focusing only on Western European history and devoting none of his book to Eastern European, Asian, or African history.^[76] Amy Finnerty described Eco’s work On Ugliness favorably.^[80]

Chinese philosophy

Chinese philosophy has traditionally not made a separate discipline of the philosophy of beauty.^[81] Confucius identified beauty with goodness, and considered a virtuous personality to be the greatest of beauties: In his philosophy, “a neighborhood with a ren man in it is a beautiful neighborhood.”^[82] Confucius’s student Zeng Shen expressed a similar idea: “few men could see the beauty in some one whom they dislike.”^[82] Mencius considered “complete truthfulness” to be beauty.^[83] Zhu Xi said: “When one has strenuously implemented goodness until it is filled to completion and has accumulated truth, then the beauty will reside within it and will not depend on externals.”^[83]

Human attributes

Main articles: Physical attractiveness and Feminine beauty ideal

The word “beauty” is often^{[how often?]} used as a countable noun to describe a beautiful woman.^[84][85]

The characterization of a person as “beautiful”, whether on an individual basis or by community consensus, is often^{[how often?]} based on some combination of inner beauty, which includes psychological factors such as personality, intelligence, grace, politeness, charisma, integrity, congruence and elegance, and outer beauty (i.e. physical attractiveness) which includes physical attributes which are valued on an aesthetic basis.^{[citation needed]}

Standards of beauty have changed over time, based on changing cultural values. Historically, paintings show a wide range of different standards for beauty.^[86][87]

A strong indicator of physical beauty is “averageness“.^[88][89] When images of human faces are averaged together to form a composite image, they become progressively closer to the “ideal” image and are perceived as more attractive. This was first noticed in 1883, when Francis Galton overlaid photographic composite images of the faces of vegetarians and criminals to see if there was a typical facial appearance for each. When doing this, he noticed that the composite images were more attractive as compared to any of the individual images.^[90] Researchers have replicated the result under more controlled conditions and found that the computer-generated, mathematical average of a series of faces is rated more favorably than individual faces.^[91] It is argued that it is evolutionarily advantageous that sexual creatures are attracted to mates who possess predominantly common or average features, because it suggests the absence of genetic or acquired defects.^[92][93][94]

Since the 1970s there has been increasing evidence that a preference for beautiful faces emerges early in infancy, and is probably innate,^[95][96][97] and that the rules by which attractiveness is established are similar across different genders and cultures.^[98][99]

A feature of beautiful women which has been explored by researchers is a waist–hip ratio of approximately 0.70. As of 2004, physiologists had shown that women with hourglass figures were more fertile than other women because of higher levels of certain female hormones, a fact that may subconsciously condition males choosing mates.^[100][101] In 2008, other commentators have suggested that this preference may not be universal. For instance, in some non-Western cultures in which women have to do work such as finding food, men tend to have preferences for higher waist-hip ratios.^{[102][103][104]}

Exposure to the thin ideal in mass media, such as fashion magazines, directly correlates with body dissatisfaction, low self-esteem, and the development of eating disorders among female viewers.^[105][106] Further, the widening gap between individual body sizes and societal ideals continues to breed anxiety among young girls as they grow, highlighting the dangerous nature of beauty standards in society.^[107]

Western concept

A study using Chinese immigrants and Hispanic, Black and White American citizens found that their ideals of female beauty were not significantly different.^[110] Participants in the study rated Asian and Latina women as more attractive than White and Black women, and it was found that Asian and Latina women had more of the attributes that were considered attractive for women.^[111] Exposure to Western media did not influence or improve the Asian men’s ratings of White women.^[112]

One study found that East Asian women in the United States are closer to the ideal figure promoted in Western media, and that East Asian women conform to both Western and Eastern influences in the United States.^[113][114] East Asian men were found to be more impacted by Western beauty ideals then East Asian women, in the United States. East Asian men felt as though their bodies were not large enough and therefore deviated from the Western norm.^[115] East Asian men and white Western women were found to have the highest levels of body dissatisfaction in the United States.^[116] A study of African American and South Asian women found that some had internalized a white beauty ideal that placed light skin and straight hair at the top.^[117]

Eurocentric standards for men include tallness, leanness, and muscularity, which have been idolized through American media, such as in Hollywood films and magazine covers.^[118]

In of the United States, African Americans have historically been subjected to beauty ideals that often do not reflect their own appearance, which can lead to issues of low self-esteem. African-American philosopher Cornel West elaborates that, “much of black self-hatred and self-contempt has to do with the refusal of many black Americans to love their own black bodies-especially their black noses, hips, lips, and hair.”^[119] According to Patton (2006), the stereotype of African-American women’s inferiority (relative to other races of women) maintains a system of oppression based on race and gender that operates to the detriment of women of all races, and also black men.^[120] In the 1960s, the black is beautiful cultural movement sought to dispel the notion of a Eurocentric concept of beauty.^[121]

Much criticism has been directed at models of beauty which depend solely upon Western ideals of beauty, as seen, for example, in the Barbie franchise. Criticisms of Barbie are often centered around concerns that children consider Barbie a role model of beauty and will attempt to emulate her. One of the most common criticisms of Barbie is that she promotes an unrealistic idea of body image for a young woman, leading to a risk that girls who attempt to emulate her will become anorexic.^[122]

As of 1998, these criticisms of the lack of diversity in such franchises as the Barbie model of beauty in Western culture, had led to a dialogue to create non-exclusive models of Western ideals in body type for young girls who do not match the thinness ideal that Barbie represents.^[123] Mattel responded to these criticisms.

In East Asian cultures, familial pressures and cultural norms shape beauty ideals. A 2017 experimental study concluded that Asian cultural idealization of “fragile” girls was impacting Asian American women’s lifestyle, eating, and appearance choices.^[124]

Effects on society

Researchers have found that good-looking students get higher grades from their teachers than students with an ordinary appearance.^[125] Some studies using mock criminal trials have shown that physically attractive “defendants” are less likely to be convicted—and if convicted are likely to receive lighter sentences—than less attractive ones (although the opposite effect was observed when the alleged crime was swindling, perhaps because jurors perceived the defendant’s attractiveness as facilitating the crime).^[126] Studies among teens and young adults, such as those of psychiatrist and self-help author Eva Ritvo show that skin conditions have a profound effect on social behavior and opportunity.^[127]

How much money a person earns may also be influenced by physical beauty. One study found that people low in physical attractiveness earn 5 to 10 percent less than ordinary-looking people, who in turn earn 3 to 8 percent less than those who are considered good-looking.^[128] In the market for loans, the least attractive people are less likely to get approvals, although they are less likely to default. In the marriage market, women’s looks are at a premium, but men’s looks do not matter much.^[129] The impact of physical attractiveness on earnings varies across races, with the largest beauty wage gap among black women and black men.^[130]

Conversely, being very unattractive increases the individual’s propensity for criminal activity for a number of crimes ranging from burglary to theft to selling illicit drugs.^[131]

Discrimination against others based on their appearance is known as lookism.^[132]