Do you see what I see?
It’s an age-old philosophical question and, unfortunately, not one that we’re likely to solve any time soon. That’s because everything that we perceive is a subjective experience. Our minds construct images in our conscious perception from light information that comes in through the eyes – and that process is invisible to the tools of science.
In the normal course of life, this doesn’t cause much of a problem. It doesn’t matter whether one person’s red is another person’s blue. However, when it comes to product selection, it makes a difference. At Bean Bags R Us, we might claim that a product is olive colour, but you might see it as light brown. Or we might say it is grey when you see it as taupe – not good.
Do You See What I See? It’s Deeply Philosophical
In the past, researchers largely believed that we all saw colours in roughly the same way. They thought that our minds had specific ways of representing blue, yellow, red, green, brown and every other colour, so perceptions would also be the same. After all, people largely agree on the colour of things in the environment. The sky is blue, the sun is yellow, grass is green and so on.
However, more recent experiments cast doubt on this view. It seems like there is no fundamental reason why our minds should represent colours in the same way. For some people, the colour wheel might be rotated, so what you see as green, they see as yellow. Their conscious experience of it is different.
Because the mind generates colour subjectively, it’s hard for science to get a handle on the issue. Theoretically, advanced technology could scan every chemical and electrical process in your brain and say “this person is seeing the colour yellow.” However, no matter how much scanning a researcher did, they could never know whether your subjective experience of the colour yellow was the same as somebody else’s.
This is what philosopher David Chalmers calls the “hard problem of consciousness.” Scientists can scan the brain all they like and map out all the details, but they can’t ever predict what it feels like to experience a particular colour.
Chalmers makes the point clear with a simple thought experiment. He, like many others, believes that one day, it may be possible to map the brain, measure all the chemical reactions, and say “that’s why consciousness happens.” However, no amount of science will ever be able to tell us why conscious experiences feel the way they do. Neither can science tell us why nature allows conscious experience at all. We can probe all the chemical reactions as much as we like, but we can never use them to understand why a subjective experience emerges. That seems to be a brute fact of nature.
To make this clearer, let’s say that you see a yellow bean bag that you like online. Your monitor emits the colour yellow in visible light that travels as a wave before hitting the retina at the back of your eye. The retina then receives the information and converts it into a string of chemical information. This chemical information then travels along the optic nerve to the visual cortex. The brain then uses the data to construct an image of the yellow bean bag you see on your monitor in your mind.
Now imagine if you could watch all the chemical reactions involved in processing the visual information coming through your eyes so that you could see every little change in the brain that occurred. Without knowing what the colour yellow was beforehand, could you figure out how it felt to experience it from chemical information in your nerves? Philosophers, such as Chalmers, would say that you can’t. It doesn’t matter how much objective data you collect, you will never be able to rationalise why the experience of the colour yellow is the way that it is. Our experience of yellow is uncompromisingly personal.
Our Brains May “Make Up” New Colours
Given these philosophical conundrums, researchers are actually quite limited in their capacity to address the question “do you see what I see?” Stepping into somebody else’s conscious mind and seeing what they see isn’t something the universe allows (as far as we know). However, investigators are probing related questions.
One line of research is whether our brains can generate new colours following changes to the light-sensing apparatus at the back of the eye.
Researchers chose to experiment on male squirrel monkeys because they only have blue- and green-sensing cones at the back of their eyes. For them, red is indistinguishable from other shades of grey. So when presented with red dots on a grey background, they don’t respond to them.
In the experiment, researchers injected the monkeys with a virus that switched some of their green-sensing cones to new red-sensing cones. The monkeys’ brains had no capacity to see red before, but once injected with the virus, they were able to pick it out of the same grey background. Therefore, the question is “what colour did they see?”
From our perspective, what is incredible about this experiment is that the monkeys were having a new phenomenological experience. They were able to see a colour that they hadn’t been able to see before. Once they had the visual apparatus to detect it, their brains simply created it.
Do You See What I See? Impossible Colours
It’s not just monkeys, though, who can see new colours. It turns out that we can too.
The human visual cortex has two opponent neurons that function in a binary way: the blue-yellow opponent and the red-green opponent. Critically, these neurons can’t signal the same colours to the brain at the same time. They are either blue/red or yellow/green – not both.
Now, you might be thinking, “yes, but I can see green which is a combination of blue and yellow, or brown, which is a combination of red and green.” But that’s not quite how it works. These colours are actually mixtures, not a single pigment that is equally red and green or blue and yellow.
In the 1970s, researchers thought that it was impossible for the human brain to see true blue-yellow or red-green because of the way the individual neurons fire. But in the 1980s, a pair of researchers, Thomas Piantanida and Hewitt Crane, devised an experiment that would trick the eyes into seeing these impossible colours.
Subjects looked at a screen displaying red and green side by side while wearing head-stabilising and eye-movement sensing devices. The technology moved images so that participants would always receive the same quantity of red and green light to their eyes. After spending some time staring at the images, the majority of participants reported seeing new colours forming along the border between red and green for the first time – the alleged impossible colour.
The academic community believed that the results were phony, and so impossible colour ideas went out of fashion. However, in 2010, new and better research confirmed the earlier results, suggesting that humans and squirrel monkeys both have the ability to perceive new colours.
The idea that you might be able to perceive a new colour that you’ve never seen before sounds crazy when you first hear it because it is impossible to imagine the experience.
However, that’s only because we can’t remember visual novelty. We learned to perceive all of the colours that we will ever see by age one. It is not true of other senses. We taste new flavours all the time. For instance, if you have never tasted fennel before and you try it, you’ll experience it as something different from, say, eating an orange. The same goes for sounds and even touch. Our brains come up with ways of representing these experiences to our conscious selves instantly. Why would colour perception be any different?
How Do We Respond To Colours?
Even if we perceive colours differently, researchers think that we respond to them in an emotionally similar way – something we discuss in this post. Light blue wavelengths, like those we see when we look up at the sky, make us feel calm. Yellow, red and orange tend to make us feel more alert.
These responses appear to be evolutionary in nature. Humans have them, but so too do other mammals, fish and even single-celled organisms as a way of optimising activity along day and night cycles. Life tends to be more active during yellow light periods, such as dawn and dusk, whereas it is less active during blue-light periods, such as the middle of the day and night time. Researchers hypothesise that life is less active during the middle of the day because of UV and at night because of predators.
What’s interesting is that it doesn’t seem to matter how organisms detect blue or yellow light – whether through eyes, light-sensitive patches or light-detecting organelles. In each case, their behaviour is similar. When it is morning and evening, they become active, whereas when it is night or the middle of the day, they are less active. Colour, rather than light intensity, therefore, could be what primarily drives tiredness.
Knowledge Affects The Colours That We Perceive
What you think you know about the world also changes how you perceive colour. Say, for instance, you meet somebody who looks pale. Without some form of knowledge (whether instinctual or learned), you wouldn’t know anything was wrong. But because you associate paleness with sickness, you can immediately detect a problem.
Researchers regularly play with this phenomenon, changing the colour of everyday items, like strawberries, and watching how experimental participants respond. In one study, scientists put volunteers in a room lit by yellow lights similar to energy-saving varieties you often find in car parks. These lights disrupt the brain’s ability to detect colour, causing everything to look pallid and brown.
When participants examined objects in this environment, they could still recognize what they were – a strawberry was a strawberry – but they didn’t feel like eating it. Furthermore, other study participants looked sick and ill.
Researchers hypothesized that the colour change violated the participants’ knowledge of how certain objects should appear. Changes in perceptions were particularly apparent when it came to evolutionarily imperative things like food and other people. Participants were often willing to eat foods in normal light, but not so keen in the yellow light. Similarly, in normal light, most participants looked attractive, but in colour-distorted light, they were less appealing.
Research like this might explain why we have such visceral reactions to red faces or pale skin. We associate them with things like anger, embarrassment, illness and disease. In evolutionary terms, being able to see in full colour was an advantage because it allowed us to better navigate our environment. We could understand the world around us better without having to touch or taste things first. So we might interpret colours differently depending on our emotional response to them.
Our Brain Responses To Colour Are Similar
Other experiments look at whether the way our brains respond to colour is similar. This approach doesn’t deal with Chalmers’ hard problem of consciousness: we still don’t know whether perception is the same. But it does tell us whether brains, in general, process colour information in the same way.
Researchers used magnetoencephalography techniques to study the electrical patterns of volunteers’ brains after exposing them to various colour images. Using scanning and machine learning, they created correlations between different brains to see whether there were any similarities.
The results were striking. It turned out that participants’ brains responded to colours in much the same way, suggesting that there is such a thing as a “red” or “blue” signature in the brain. However, each brain was slightly different.
Researchers then asked whether the relationships one person perceives between colours differs from another. So, for instance, is the way one person relates pink and red the same as somebody else?
It turns out that, again, our relationships between different colours are also similar. So when a person sees red, they also know that orange is a similar colour. As before, whether the actual experience of those colours is the same cannot be proven. However, researchers now think that the brain does form relationships between colours on a consistent basis between people, based on neural activity.
Do We See The Same Colours?
Given the philosophical problems outlined above, we probably won’t know for sure whether we see the same colours. The broad body of research on the subject suggests that we probably see approximations of what others see. However, because there are differences in the rods and cones in our eyes and the brain structures responsible for visual processing, there are likely differences too.
This variation is clear when you ask people to select their best example of a particular colour. Researchers find that we typically don’t agree on what shade is the most red or the most green. For some, the “most red” will look scarlet, while for others it will be salmon pink.
Furthermore, researchers don’t seem to be able to make up their minds as to whether these perceptual differences are biologically or culturally determined. They flip-flop between the assertion that biology is the driving factor and that personal identity factors, such as gender, nationality and geography, are more important.
There may also be differences in the way the sexes see colour on a genetic level. Women have two copies of the X chromosome – the part of the genome responsible for colour discrimination. As such, it could be possible for them to see more detail in colour than men. They may also be able to see a wider spectrum of colours, running more into the infrared and ultraviolet.
Around 40 percent of women may have tetrachromatic vision. In other words, their genes may encode for the creation of four different types of cones, instead of the usual three. Early experimental research in spider monkeys and human women suggest that this type of vision is real and women who have it can see more colours.
So, we finally have an explanation for why some people differ on product colours. At Bean Bags R Us, we describe the colours of bean bags based on standard colour charts for people with regular “trichromatic” vision. However, our colours will appear differently to people with “dichromatic” (colour-blind) or tetrachromatic vision.
Therefore, product manufacturers and sellers should offer customers colour images that accurately accommodate their type of vision. That way, product retailers could avoid disappointed customers.
Naturally, that approach is still quite some way away – especially for something as novel as tetrachromatic vision. But it will eventually come as we understand more about colour.
So, do you see what I see? Unfortunately, the age-old question of whether one person’s red is the same as another’s isn’t answerable – at least not at the moment. But we do now know more than ever before about the brain, colour perception and why we see the way we do.