Color Vision 101: How To Turn Disability Into Superhuman Perception

Humans can only see 2% of the full light spectrum. This animated post reviews the science and evolution of perception, plus describes how to build new colors and improve our sight.

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Imagine what your life would be like without colors. You would still be able to interact with a grayscale environment, but achromatic life would be duller. Now, imagine waking up seeing 10x as many colors—how otherworldly and hyperstimulating it would be! Our evolved sense of vision is something nearly all of us use, and take for granted, everyday.

Illusions and the Nature of Color

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Children may tell you that plants are green and the sky is blue, but they’re only half right. As 2015’s blue/black or white/gold dress demonstrated, the colors that we see are often illusions.

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While staring at the dot, your eyes become tired of looking at the colors, which act as a negative for the scene. When the bar fills and you’re shown the black and white photograph, your cone cells (more on them soon) compensate by filling in color. This is known as the afterimage effect.

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If you like optical illusions, check out Akiyoshi Kitaoka’s work! Beau Deeley used 1 of his famous patterns to create this static image, in the shape of a horn torus.

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The colorless atmosphere of gases and particles suspended above the Earth acts like a prism, and filters white sunlight. The sky appears blue during the day, and kaleidoscopic around dusk and dawn, due to Rayleigh scattering.

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Our eyes see color due to surfaces reflecting light. Basically, plants appear green because they reflect green light into our eyes and absorb the other colors of light. Objects have color due to either pigment or, less commonly, structural color.

The main difference between pigments and structural colors is that pigments appear the same regardless of what angle you view them from. In contrast, structural colors are iridescent and appear to change from different angles (like bubbles).

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Surfaces can have both structural and pigment color, like peacock plumage. These feathers are pigmented brown with melanin, and have microscopic structures that selectively reflect blue, turquoise, and green light.

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By embossing metals with microscopic patterns (around 100nm across), scientists are able to create green gold, red silver, and a multitude of other unprecedented metallic colors without coating or chemically treating them.

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The brightest color in nature is the Pollia condensata fruit, which reflects 30% of light. This inedible, metallic berry produces its vibrant blue due to nanoscale cellulose strands twisted in its skin.

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Applying this knowledge led to the darkest material ever created, Vantablack, which absorbs 99.965% of visual light! It’s engineered out of tightly-packed carbon nanotubes that trap incoming light. It even reflects less light than Aeroglaze, the black paint used to minimize light distortion around the Hubble telescope so it can photograph stellar images.

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Also worth noting: Burning different elements and materials produces various colors of light.

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Neon lights are popular due to their bright glow and customizable shapes. These bendable glass tubes are electrified, which causes the contained gas(es) to ionize and emit a colored light. For example, electrified neon gives off orange light and carbon dioxide white.

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Have you ever noticed that you look more photogenic in sunlight than you do in fluorescent light? The sun, flames, and incandescent light bulbs emit light via thermal radiation, which contains a broader spectrum of light than computer screens and LEDs. This means that the objects they shine on reflect more colors, making them appear warmer.

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Colors that appear to be inherent to objects actually depend on the available light source. For example, ripening bananas appear bright indigo under blacklight.

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Similarly, gems with pleochroism appear to be differently colored when viewed from different angles (like this tourmaline).

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The 3 primary colors of light (as seen in digital screens) are red, green, and blue, a.k.a the additive colors. The 3 basic colors used for mixing pigments (used in paints, dyes, and inks) are magenta, cyan, and yellow, a.k.a. the subtractive colors. All 3 additive colors mix to form white (all colors together), and all 3 of the subtractive colors mix to form black (the absence of color). Additionally, mix any 2 of the primary colors of pigment and the sum will be 1 of the primary colors of light - the opposite is also true!

How Human Eyes Work

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Assuming you’re human, like I am, then our eyes function more or less the same way. First light hits the cornea, the topmost layer of the eye which bends light in toward the pupil.

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The colored ring around your eyes is called the iris (same name as the Greek goddess of the rainbow), which stands out against the white sclera. The iris dilates and contracts to control how much light enters your eye, via the central pupil.

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Like in a camera, the lens angles and focuses the light onto the retina. When fully developed, our eyes are slightly smaller than a gumball (24mm versus 27mm) and our lenses are the size of M&Ms.

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You're not looking at a sea anemone, but rather a close-up view of the retina, the light-sensitive tissue lining the inner surface of the eye. It’s made of up rods, which sense light intensity, and cones, which sense color.

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Information about the visual environment travels from the retina, through the optical nerve, to the brain. Processing and making sense of what we see takes more brainpower than any other sense; roughly half of the brain is involved!

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Most humans are trichromats, possessing 3 types of color-sensitive cones, attuned to blue, green, and red. All you need to know is these cones are fundamentally responsible for our ability to distinguish colors.

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The unaided human eye can only detect 2% of the electromagnetic spectrum! This is what we call visible light, with wavelengths ranging from 380 to 740 nanometers (a nanometer is a 1 billionth of a meter).

A Flawed System

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People with color blindness are missing 1, 2, or 3 types of cones. Women generally have better color vision than men, because the genes responsible for color vision are located on the X chromosome, so women have a greater chance of having fully-functioning copies (women have 2 Xs and men have 1 X paired with 1 Y).

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Today, color blindness affects 8% of men, 0.5% of women, and everyone in dim light (despite implausible claims of a cat-eyed boy in China). The color that you see in perfect darkness is poetically known as eigengrau, which is German for “intrinsic gray."

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Many people born with ‘normal’ color vision lose it later in life, due to medications, chemical exposures, trauma, and chronic illnesses like Alzheimer’s disease, leukemia, and alcoholism, to name a few.

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Long periods of wakefulness fatigue the brain, making grays appear greenish, and sometimes causing visual hallucinations. Overnight sleep restores our color vision. Despite our reliance on our eyes and brain, it’s important to remember that they’re imperfect biological hardware devices.

How Other Animals See

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Animals eye structures and color-sensing capacities vary greatly among species.

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In real life, the Indominus rex from Jurassic World would almost certainly have round pupils. An animal’s pupil shape is closely related to its height and predator/prey relationship. For example, vertical slits are extremely common with foxes, house cats, and other short, ambush predators. Larger predators that chase prey have round pupils, like wolves, tigers, and humans. Alternatively, prey animals are very likely to have horizontal pupils and eyes on the side of their heads, which gives them a panoramic view to scan for danger (goats can see 340 degrees around them)!

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Most mammals are dichromatic, meaning they have 2 types of cones. Dogs have yellow and blue sensing cones, which give them vision similar to people with deuteranopia. This means they see red, yellow, and green as a single hue, blue and violet as a second hue, and perceive cyan and magenta as a neutral, gray hue.

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Humans aren’t just descendent from great apes; we are great apes! As such, it makes sense that many of our closest relatives, apes and Old World monkeys, are also trichromats. Other primates have paltrier color vision; for example, nocturnal prosimians can only see black, white, and gray!

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Birds have a superior color-sensing capacity, with 4 cones that are attuned to red, green, blue, and ultraviolet light. Birds are particularly drawn to reddish flowers, which insects—their pollination competition—cannot see.

In addition to their tetrachromatic vision, several birds of prey have higher resolution vision than humans. Imagine how easy finding parking would be if, like an eagle, you could see 2 miles away!

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The best eyes on the planet belong to the resplendent mantis shrimp. Their compound eyes can move independently and boast 12 distinct types of cones. They can see infrared, visible, ultraviolet, polarized light… and possibly much more!

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Trilobite eye lenses were composed of calcite crystal (the main ingredient in limestone and chalk), which aided in their fossilization and explains why we know more about their vision than other prehistoric creatures. Their rigid composition meant they couldn’t adjust focus, and so they evolved the ability to keep both near and far objects in focus at the same time!

Superhuman Color Perception

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These animals’ abilities remind us that we’re not fully evolved. However, technology can compensate for our shortcomings, mimicking and even surpassing what is biologically feasible!

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Brain-computer interfaces can sharpen our vision, allow us to view the same point from different perspectives, or even enable us to focus on everything we see simultaneously (making peripheral vision a thing of the past)! These advancements are possible in the next decade, but humanity still has a long way to go before we meld into an omnipresent hive mind...

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Up to 3% of women are born tetrachromats. Their fourth cone confers them with extraordinary color vision, allowing them to potentially distinguish10x as many distinct colors as the rest of us (up to 100 million hues)!

Gene sequencing will allow us to identify this rare talent, and someday gene editing will allow us to confer this ability on ourselves, or our children.

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Most people are born less visually gifted, but EnChroma (sun)glasses provide wearable hope by saturating the world with color. For a few hundred dollars, these spectacles enable people with the most common form of color blindness, deuteranopia, to see colors. What’s more, they boost colors for the visually unimpaired too!

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Individuals hoping for a more permanent solution may soon be able to get a single shot to restore their color vision. Doctors Jay and Maureen Neitz already developed a gene therapy that cures color blindness in monkeys, and human testing will begin as soon as 2017.

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Neil Harbisson was born with complete color blindness, achromatopsia, but now can hear color thanks to his prosthetic antenna. It uses a camera to pick up light frequencies and then delivers them as sound waves to his skull via bone conduction. Now, he can distinguish among different wavelengths of light with a greater degree of specificity than most people.

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He cofounded Cyborg Nest, which aims to “focus on the creation of new senses to extend your perception of reality and explore nature in a deeper way.” This unconventional venture can outfit you with technological synesthesia, or help convert your disability into superability, if you desire.

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It’s a common misconception that humans have only 5 senses (dating back to Aristotle). Many people count up to 21, including a sense of balance, time, pain, hunger, thirst, etc. The more the merrier!

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Imagine going to the grocery store with a special camera aperture that can analyze the pH or bacterial content of food to accurately estimate how many days it'll will last before spoiling. Impact Vision is a startup working to drive down the price of hyperspectral imaging to make this technology affordable to us consumers.

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Humans may be able to naturally see some infrared light. Some people report seeing laser light with wavelengths above 1,000nm as white or green. Biohackers suspect that a dietary change may shift their visual perceptive limits. By consuming enough vitamin A2—to generate porphyropsin, a derived photosensitive pigment naturally found in other species—they hope to see longer wavelengths of light.

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Artists see the world differently, Claude Monet more than most. After cataracts frosted his vision with a yellowish film, he had the lens of his right eye removed, which allowed him to see brilliant blues, violets, and whites. Our blue-sensing cones are naturally able to sense into the ultraviolet range (down to 300nm), but our lenses typically filter out the shorter wavelengths of light. Monet painted the same scenes at different times of his life, so we have a sense of how his view of the world evolved.

The Evolving Language of Color

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We all subjectively experience color, but it can be quantified objectively too. Colors have 3 properties: hue (amount of each primary color), saturation (bright/dull), and value (light/dark).

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People express their color preferences in various ways. These eccentric New Yorkers, Elizabeth Sweetheart and Valeria McCulloch, wear their favorite colors everyday, without exception!

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Next time you guess what someone's favorite color is, remember that blue is the safest bet. An astonishing 42% of men and 30% of women named it as their favorite hue in a 2011 survey of 30 countries by Dulux Paints.

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William Gladstone, a classicist and British prime minister, discovered a term for blue was missing in almost every ancient language, from Chinese and Indian to Hebrew and Greek. Homer famously describes the sea as “wine-dark” in The Odyssey. Egyptian blue is the oldest artificial pigment, which explains why their culture was the only exception with a word for the color.

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Edward Waldo Forbes—whose father cofounded Bell Telephone Company and whose grandfather was the poet Ralph Waldo Emerson—was an art collector who amassed a collection of thousands of pigments, to sleuth out art forgeries. The Harvard Art Museum's Straus Center for Conservation and Technical Studies stores most of his collection (and adds modern samples), similar to how seed banks store biological samples.

Many are antiquated and costly to produce; for example, mummy brown was made from the ground-up remains of Egyptian mummies (plus myrrh and white pitch), while producing an ounce of Tyrion purple took 250,000 fermented mollusk shells.

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The first color words in every language were black and white, or dark and light. Next came red, the color of blood and wine. After that, either yellow or green appeared, followed by blue.

For centuries, the color orange was known as red-yellow. The color was named after the bitterness of the eponymous fruit's rind, sometime during its westward journey. According to The Secret Language of Color: ‘Most likely first cultivated in China, cheng zi fruits traveled from Persia to Moorish Spain, taking on native pronunciations along the way; from narang in Persian to naranj in Arabic and from naranga in Sanskrit to naranja in Spain. Once oranges arrived in France, the word took on a little twist and became orenge. From there, it was only a small step across the pond to Great Britain and orange.’

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The language of color continued to evolve over time and across geographies. For example, the color Sir Isaac Newton called blue is what we now call cyan (greenish blue). What he called indigo is what most of us would now identify as true blue (which falls midway between green and violet).

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Rainbows used to be comprised of 7 colors - red, orange, yellow, green, blue, indigo, violet - but modern depictions squeezed indigo out. This can be seen from gay pride flags to Pink Floyd’s Dark Side of the Moon album cover. Language structures play a major role in how we individually experience color.

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The seminal book, Basic Color Terms, explains that most post-industrial languages have 11 basic color words: red, green, blue, yellow, black, white, grey, pink, orange, purple, brown. Exceptions exist: Russian and modern Greek each have 12 basic colors, because of their differentiation between light and dark blues. In contrast, tribal languages often have fewer distinctions: Himba speakers (like the lady pictured) in Namibia and Berinmo speakers in New Guinea have 5 basic color terms, including 1 for grue (green-blue).

The different classification structures change how we perceive the world, a theory called linguistic relativity. This has been tested time and again, using color swatches. In a timed experiment, subjects are shown multiple squares of color and asked to identify which one is different.

In 2007, MIT researchers proved native Russian speakers can discriminate between light and dark shades of blue much faster than English speakers. It’s important to note that regardless of native tongue, we are all genetically modern humans with more-or-less the same capacity to perceive colors.

Macy's ad in the New York Times

As this ad from 1929 demonstrates, our cultural associates with color continuously evolve. Less than a century ago, blue was for boys and pink was for girls.

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In a truly romantic gesture, the Hindu deities Krishna and Radha applied powder to their faces to make their skin colors more similar. To this day, Holi, the festival of colors—and one of the largest festivals in the world—is celebrated to remind us to embrace love and diversity. Regardless of the inconsequential amount of brown melanin in our skin, with a little bit of brightly colored powder, we all look the same anyway!