About one percent of people worldwide can see 99 million more colors than the average person, creating a more vibrant world and revealing shades invisible to most people.
Tetrachromacy is a rare genetic trait that gives people, especially women, a fourth color-detecting cone in their retina.
Most people have three cones in their eyes that detect variations of red, blue and green along the visible light spectrum. Tetrachromats have four.
Tetrachromats can distinguish between more colors within the range of light visible to humans, allowing them to distinguish more subtle color variations.
To see if you might be a tetrachromat, look at the spectrum and see how many shades you can distinguish. Most people can see it between 20 and 32 colors in the spectrum, bPeople with tetrachromacy must be able to see at least 33 to 39 colors.
Most people can see between 20 and 32 colors, but people with tetrachromacy should be able to see at least 33 to 39 colors. Take this test with a grain of salt, however, as computer monitors cannot display the full range of colors that a test with a doctor can provide.
Concetta Antico, a tetrachromat, said she knew there was something different about her vision since she started teaching art classes: “I would say, ‘Look at the light on the water – do you see the pink shimmering over that rock?’” The students nodded politely, but the colors she saw so vividly were invisible to them.
Tetrachromacy involves the light-sensitive retina at the back of the eye, which contains cells called photoreceptors that handle color vision.
The retina sends light signals to the brain via the optic nerve. Once these signals reach the parts of the brain responsible for vision, they are converted into the images we see.
These photoreceptors consist of rods and cones. Rods enable the eye to detect light and see in the dark, while cones enable the eye to see and distinguish colors.
Most people are trichromatic, meaning the three types of cone cells in their eyes are sensitive to three wavelengths of light: red, blue and green. The combination of signals from these three allows us to see a wide range of colors.
Tetrachromats, meanwhile, have four types of cone cells in their eyes. The fourth cone is sensitive to a wavelength between red and green, allowing some people to see a much wider range of colors than trichromats.
Up to 12 percent of women and eight percent of men can be tetrachromatic.
Certain visual tests, including the one pictured, can help determine whether a person is tetrachromatic, although genetic testing is the only way to know for sure. Computer monitors can only display a limited range of shades, so take the online tests with a grain of salt. Doctors often perform these tests personally to get a more accurate result.
Ms. Antico shows what her world looks like in vibrant paintings in her California gallery.
She knew since she was young that her eyes saw the world differently than other children’s, and she knew from an early age that she would pursue a career in art.
Concetta Antico’s art captures the wide range of colors that tetrachromats can see. Her works can be seen in San Diego, California. Thanks to Concetta Antico
When painting eucalyptus bark, Ms. Antico said the tubes of paint flew around and the result was a multi-colored tree with shades of purple, red, orange, blue and yellow.
She told the BBC that while painting a eucalyptus tree: ‘The tubes of paint were flying.
‘The yellows, the violets, the lime greens – I was frantically mixing on the palette trying to create all the flows of color in the bark.’
It wasn’t until she underwent genetic testing in 2012 that she couldn’t be sure there was actually anything different about her vision.
Genetic testing looks for mutations in two genes on the X chromosome that program the eyes’ ability to pick up red and blue.
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Because the genes are located on the X chromosome, tetrachromacy is more common in women with two X chromosomes and they may carry different versions of the opsin genes.
Men, on the other hand, have only one X chromosome, which makes them less likely to develop specific gene mutations.
Concetta Antico’s visibility is especially improved at night, as seen here. Thanks to Concetta Antico
People with these mutations can develop a fourth cone in their retina, which can detect wavelengths of light that fall between the range detected by the red and green cones (the long- and medium-wavelength cones).