Color doesn’t exist—at least not how you think

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Red means stop. Red means danger. Red means passion. The color conjures up a whole range of emotions and associations. It inspired an entire Taylor Swift album. And yet if someone asked you to describe what red actually looks like, without pointing at something red, you’d hit a wall almost immediately. 

So why is it that a color so evocative and distinctive as red (or any color, for that matter) still manages to elude our attempts to nail it down with words? 

If you just now said, “It’s because color doesn’t exist,” well played!  If you’re like me and your face just turned an indescribable shade of red, welcome to the club. 

“There is no color in the world,” says American neuroscientist Christof Koch. “There are photons of a particular wavelength emitted by the sun that strike an object, and then get reflected into the eye of the viewer. The electrical activity that’s generated there then travels up into the cortex of the brain, and gets processed into something we call color.”

In other words, red isn’t something out there in the world waiting to be objectively and uniformly experienced. It’s something your brain makes up. So does color even actually exist? Neuroscientists think maybe not. At least not in the way we think it does. 

Does color even exist? Short answer: Not really.

Koch, a Meritorious Investigator at the Allen Institute for Brain Science, discusses the subjective experience of color using a famous thought experiment called Mary’s Room. Introduced in the 1980s by the philosopher Frank Jackson, the experiment involves a hypothetical neuroscientist, Mary, who lives in a black-and-white room. Mary knows everything there is to know about color: the wavelengths, the photoreceptors, the way color is processed within the visual cortex. She has read every paper and has conducted every experiment. But Mary has never actually seen color.

One day, Mary leaves the black-and-white room. And for the first time in her life, she sees a red tomato.  

The question Jackson posed is deceptively simple: When Mary sees the red tomato, does she learn something new?

Jackson’s answer was yes. Despite knowing everything science could conceivably tell her about color, Mary is confronted by something that no textbook could convey—the actual experience of seeing red. 

“The feeling, the phenomenal quality, whatever you call it—the experience is subjective,” Koch says. “People have invented a dozen words or more to describe it. It remains inexplicable.”

That “it,” Koch says, is the experience itself—the felt sensation of seeing red that no amount of scientific language has ever quite managed to pin down.

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Philosophers call that experience a quale (pronounced KWAH-LAY) the felt, first-person experience of something: the redness of red, the sharpness of pain, the taste of coffee. Unlike the wavelength of red, which can be measured precisely, a quale can’t be objectively measured. It’s entirely an inside job.

Koch says the Mary’s Room thought experiment argues against materialism—the philosophical view that everything in the universe, including human experience, can be explained by physics. If materialism is right, there’s nothing science can’t eventually account for. Mary’s Room suggests otherwise: There are some things that science simply can’t explain.

Everyone see colors differently, but not that differently

For the most part, we go about our days equipped with this surprisingly loose consensus on our shared reality. If your blue isn’t quite the same as my blue, it’s close enough not to cause trouble most of the time. But every once in a while, something happens that reminds us how differently our brains can construct the same reality. 

In 2015, a photograph of a striped dress went viral for a reason that had nothing to do with fashion. The dress appeared blue and black to many, but millions of people looking at the same image saw white and gold, and couldn’t fathom how anyone could see it differently. In what now seems like a quaint public rift, the internet divided around the hotly debated reality of blue/black versus white/gold.

“It’s as though they were looking at the same screen,” says Koch. But “half the population saw one movie and the other half saw a different movie.” 

The explanation, says Koch, has to do with how the brain handles ambiguous lighting. Every time you look at an image, your brain makes an automatic, unconscious calculation about the overall brightness of it. This calculation is based on your habits and life experience. 

Research by NYU neuroscientist Pascal Wallisch, drawing on more than 13,000 participants, found that early risers were significantly more likely to see the dress as white and gold, while night owls tended to see blue and black

Because early risers spend more waking hours in natural daylight, their brains are calibrated to filter out blue light, leaving white and gold. Night owls, accustomed to warmer artificial light, filter that out instead and land on blue and black. 

“You get up early in the morning and see a lot of sunlight, or you get up very late and are primarily up at night with artificial light,” Koch says. “So depending on that implicit assumption, your brain gives rise to these two different percepts: white and gold, or blue and black.” It’s not a conscious, deliberate decision you take to view the dress one way or the other. 

Does this dress look blue and black or white and gold? Your answer might have to do with whether you’re an early riser or night owl. Video: What Colour Is This Dress? (SOLVED with SCIENCE), AsapSCIENCE

For Koch, the dress is a window into something fundamental about human perception.

“There is input from the world, but then your particular brain might make a set of assumptions, and my brain might make a different set of assumptions,” he adds. “We obviously agree most of the time, though, or else we wouldn’t have evolved.”

And for the most part, we do agree. A species that couldn’t agree on some basic shared realities wouldn’t have gotten very far. So don’t worry: Your understanding of red is probably pretty similar to my understanding of red.

We all have unique, built-in filters that change how we see the world

The dress, it turns out, is just the beginning. Koch cites the concept of the “perception box.” Writer and researcher Elizabeth R. Koch (no relation) coined the term in 2021 to describe the hidden forces that shape how we see the world. 

According to this theory, we each have our own unique perception box. Think of two people standing in front of the same abstract painting. One sees something beautiful and moving: The other sees a mess. Same painting, completely different experience. That’s your perception box at work. It’s shaped by your genes, your upbringing, and every experience you’ve ever had. 

“We all live in slightly different perception boxes,” he says. “The walls are invisible, and they can expand or shrink, driven by our genes, our neural wiring, our experience.”

Those walls, Koch says, determine far more than which colors we see. They shape how we interpret relationships, how we process emotions, and even how we react to the evening news. Two people can look at the same event and come away with completely different realities, not because one of them is lying, but because their perception boxes are simply built differently.

When it comes to the color red, you can measure its wavelength. You can map exactly what happens in the brain when the eye encounters it. But the actual experience of redness—that felt, interior, indescribable thing—lives inside your perception box, and nowhere else.

“This applies to any conscious experience,” he says. “It applies to pain, say, due to an infected tooth, or the distress you experience when someone leaves you. It’s true for taste, for boredom, for mystical experience, and for psychedelic experience. It has the same ineffable quality.”

Which brings us back to red. You’ve always known it when you’ve seen it. But that color you see? It’s yours and yours alone.

In Ask Us Anything, Popular Science answers your most outlandish, mind-burning questions, from the everyday things you’ve always wondered to the bizarre things you never thought to ask. Have something you’ve always wanted to know? Ask us.

 

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Jennifer Byrne is a New Jersey-based freelance writer and journalist who has been published in The Cut, The New York Times, Atlas Obscura, The Guardian, The Boston Globe and more.

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