Not long ago, while I was in physical therapy, the topic of tennis came up. Someone said something about yellow tennis balls and I was like… “What? They’re green.” Then someone else chimed in: “No, they’re yellow!” And then someone across the room yelled, “No, they’re obviously green.”
Physical therapy basically caused an uproar. When I started asking other people what they thought of them – yellow or green – they told me they couldn’t believe there was even a debate. So I called Bevier Conway. He is a neuroscientist who leads a laboratory at the National Eye Institute. He is writing a book called Color codingto be released next year. He’s also a working artist – which is actually why he started working with color in the first place.
Conway told me there’s a good reason why so many people disagree with tennis. He said it was simple: “There is no such thing as color.”
in the latest episode unexplainableConway and I discussed even what color yesviral outfit wars (black and blue or white and gold?), and why we’re so frustrated when people don’t see color the same way we do. Below are excerpts from our conversation, edited for length and clarity. You can listen to the episode wherever you have podcasts or watch it on Netflix.
So you are an artist. You are also a neuroscientist. You study colors. You are also writing a book about color. Is there still a color mystery? Is there anything science doesn’t know about color?
There are many mysteries about color. For a long time, people thought that color was a bit like a filter, that everything that really mattered was black and white and then you put a color filter on top of it.
But a few years ago, my lab was surprised to find that as much of the brain processes color as it does face recognition.
Bevil Conway
Same processing power?
Yes, there are many, many organizations [and] Very exotic parts of the brain are doing pretty high-level things—parts of the brain that we think of as involved in social cognition, higher-order reasoning, and visual memory. Color must be more than just this little add-on. It’s doing something deeper. So we try to understand what these parts of the brain are doing.
so what yes color? How does it work? How do our brains and eyes perceive it?
The classic definition is: Color is a visual characteristic obtained from the wavelength characteristics of light entering the eye. People usually think of the long wavelength end as red light, and then passing through the short wavelengths, you know, following ROYGBIV: red, orange, yellow, green, blue, indigo, violet.
if color is only wavelength, then the same object looks blue under blue light, and the same object looks yellow under yellow light. That’s not very helpful – since what you want is a signal that tells you about the object, independent of lighting conditions. You want them to always have this color.
A perfect example is peaches. If you look at the outside of a peach and then look at the inside, it always looks like the color of a peach. But if you look at the wavelength patterns that are coming leave Characteristics of peaches, they vary greatly under different lighting conditions. If colors were just wavelengths, they should be different colors, but they’re not. These two different wavelength combinations appear to be the same color.
I think color is so cool because it’s so central to how we experience the world, but how it works teaches us a lot about the brain.
What we are talking about is color constancy. That is, the color of an object is constant regardless of viewing conditions.
So if the inside and outside of a peach are fundamentally different colors and our brains tell us it’s still peach, how are our brains fooling us?
So it’s not essentially a different color. The color is the same. That’s the cool thing. The thing is, Norm, you’ve got this idea in your head: color is wavelength, and That is an error.
Color is not wavelength! We’ve known this for a long time. But the problem is us think It is an empirical, measurable number that exists in the world outside of the observer and is the same number no matter who looks at it. The core of color is not like that.
Color depends on your own visual system for interacting with the world. But that doesn’t mean it’s any less real. It just means that its reality depends on psychoneurological brain processes. and that is What makes color so fascinating.
You’re saying that colors are essentially created in the brain.
Absolutely. Color is a product of the brain, providing us with reliable, useful, real, meaningful and objective information, but it itself is not [those things]. It’s something your brain creates to come up with useful and meaningful information about the world.
[Your brain is] Actually creates a color. Colors in the world do not exist independently of an observer’s observations.
Does this have anything to do with “skirts”? You know, like 10 years ago, when the photo of that dress went viral, one group of people on the internet thought it was blue and black and others thought it was white and gold, and everyone was really upset? Is it the same type of thing to see something in different light or in a different environment and perceive a different color?
This is. So this dress is fascinating because someone with normal color vision would see the exact same thing very differently.
And, you know, it’s important from a deep philosophical perspective because they’re not saying, “Yes, this looks a little different to me, but I understand how you see it as different.” They’re saying, “No, it’s white and gold.” Others are saying, “It’s a different color.”
As far as the dress goes, it’s a pretty crappy little photo, very blurry. It doesn’t give you a lot of background information. Your visual system, your own brain, you have to guess what the lighting is. If your brain guesses that the light is nice, warm, direct sunlight, then it will implicitly subtract a bit of yellow from the image and you’ll see it as blue and black. While someone else looking at the exact same pixels on the same monitor will think the lighting is cool, indirect, shadowed light from the blue sky, but their brain will color correct the image, subtracting some of the blue, and they will see it as white and gold. So the brains of these two groups just made different assumptions.
Why do you think this is so disturbing? When this happens, people can’t believe that other people can look at that dress and see a different color.
marvelous! And, I think, to this day, it remains the most popular image in the history of the internet. When it came out, my initial reaction was also like, “Well, that’s weird. I wonder what’s going on there.” A lot of my colleagues were like, “Well, maybe it has something to do with the ratio of rods to cones, or people are looking at different monitors, or maybe people are just silently color blind.”
But I think even for vision scientists, the idea that your own brain could play such an important role in determining what wavelength patterns mean doesn’t cross your mind.
I think the reason it goes so deep, if I could put it more poetically, is that our contemporary society relies on shared experiences, right? Our laws depend on shared ideas of right and wrong.
Yes, for example if mine red is your red; we still need to be able to point something And agree it’s red.
Yes, here’s an example: “It’s not white and gold, it’s blue and black, obviously. Are we living in a shared reality?”
If you can’t believe your eyes, what can you believe? I think people are really feeling like, “Is this the beginning of the end?” Like, “Is our whole society collapsing?” I mean, look at Twitter, there’s all kinds of profanity everywhere.
Have you ever had an argument over color? I once had an argument about tennis balls and their color.
Yeah, what color are they? I’m curious.
I can’t believe anyone thought they were yellow! I always thought they were green.
They are completely yellow. I mean, we can start now. You are wrong. So funny – I actually thought they were definitely yellow.
So what is tennis all about?
Tennis is fun. I mean, if you ask people to pick their best example of green, blue, red, orange, yellow, etc., there’s a lot of variation. Green and blue are the most varied. Some person’s best example of green is another person’s best example of blue.
I mean, you can ask me Choose a color that’s completely green, and then other people are like, “No, that’s blue.”
Yes, exactly. This is not language based. This is true of all cultures.
Are our perceptions of blue and green just a little bad or blurred?
Yeah, one of our thoughts on this is that blue and green aren’t really colors associated with objects.
So if I ask you what color an object is, that’s a weird question! Like, objects can be any color. But it turns out that if you actually measure, you know, the colors of the things that you choose to label in the world, most of them are yellow, brown, red, pink, and some purple, but not much.
Yeah, I guess the green and blue is the background. Just like green is the forest and blue is the sky.
Yes, exactly. And, even in nature, there are very few naturally blue objects, which is part of the reason why blue is so popular as a pigment. So the weird thing about yellow is that if you just ask people across the rainbow to choose where the yellow is, people are incredibly consistent.
So people really recognize yellow.
They really understand yellow. I think the problem with tennis is that it’s kind of fluorescent. It actually emits a little more light than it absorbs because it’s reprocessing short wavelength light in the visible spectrum.
So they chose this bright yellow, which is right at the peak of our visual system’s sensitivity. So the color of a tennis ball is the best wavelength we can detect with our eyes, and it’s right in that range, and technically it’s probably closer to green than yellow. But since it’s so bright, and yellow is considered a bright color, the brightest color, people might be persuaded to see it from the yellow direction.
What I hear you say is that I’m right – and it’s green.
Yeah yeah. Even so, I still like yellow.