Do we see colours in the same way? Or do we perceive them differently? It’s a tricky question, and there are no simple answers. Research shows that we experience colours differently depending on gender, national origin, ethnicity, geographical location, and the language we speak.
It’s an age-old philosophical question and, unfortunately, not one we’re likely to solve anytime 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 scientific tools. In the ordinary course of life, this doesn’t cause much of a problem. But it does raise the question: do we see the same colours? 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 an 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. Even a family member may disagree with you on the name of a colour due to individual perception. Some languages do not lexically discriminate between blue and green, while other languages may group blue with grey or black, reflecting distinct colour categories.
Colour categories vary across cultures and languages, and some languages have specific terms for shades like dark blue or grey.
Do You See What I See? It's Deeply Philosophical
Researchers largely believed that we all saw colours roughly the same way in the past. They thought our minds had specific ways of representing colours, so they assumed perceptions would be the same. After all, people essentially agree on the colour of things in the environment. The sky is blue; the sun is yellow; the grass is green, and so on. However, more recent experiments cast doubt on this view. There is no fundamental reason why our minds should represent colours in the same way. Some people might rotate the colour wheel. What you see as green, they see as yellow. Individual differences in biology and genetics, such as variations in cone cells and genes, contribute to these variations in colour perception. Their conscious experience of it is different. Because the mind generates colour subjectively, it’s hard for science to handle 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. Even when people agree on the same colours, it remains uncertain whether they are truly perceiving the same colours due to these individual differences. Colour vision allows for the perception of differences between light of varying frequencies, regardless of light intensity, and both biological and environmental factors influence these variations in colour perception.
Introduction to Human Colour Perception
Human colour perception is a fascinating process that allows us to experience the vibrant world around us. When light enters the human eye, it is detected by specialised cells in the retina called cone cells. These cone cells are each sensitive to different wavelengths of light, specifically, red, green, and blue. As light of various wavelengths hits the retina, it stimulates these cone cells in different combinations. The signals from the cone cells are then sent to the brain, which interprets them as specific colours. This collaboration between the eye and the brain is what enables us to perceive blue skies, green grass, and the full spectrum of colours in our environment. The way we see colour is not just about the light itself, but also about how our brains process and make sense of that information. Understanding human colour perception is essential in fields like vision science, psychology, and design, where the way we perceive colour can influence everything from how we communicate to how we experience the world.
The Philosopher David Chalmers
The philosopher David Chalmers calls this 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 subjective expertise emerges. That seems to be a brute fact of nature. Let’s say you see a yellow bean bag 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. This process underlies our visual perception of colour, allowing us to distinguish differences in light wavelengths, but it does not explain the subjective experience of colour itself. How we perceive colour can vary between individuals, influenced by genetics, brain processing, and personal experience, making the perception of colour a uniquely subjective phenomenon. The brain then uses the data to construct an image of the yellow bean bag you see on your monitor in your mind. The retina, which processes colour, is covered by millions of light-sensitive cells, including rods and cones.
Chemical Reactions
Now imagine if you could watch all the chemical reactions in processing the visual information coming through your eyes to see every little change in the brain. 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 it is. Our understanding of yellow is uncompromisingly personal.
The Science of Colour Vision
The science of colour vision is rooted in two main theories: the trichromatic theory and the opponent process theory. According to the trichromatic theory, the human eye contains three types of cone cells, each tuned to detect different wavelengths of light—red, green, and blue. These basic colours form the foundation of our colour vision, and by combining signals from these cone cells, our brains can perceive a vast array of colours. The opponent process theory adds another layer, explaining how the brain processes these signals by creating pairs of opposing colours, such as red versus green and blue versus yellow. This helps us distinguish colours more clearly and explains why certain colour combinations, like red and green, are difficult to see together. Colour vision is not unique to humans; many animals in the animal kingdom, from birds to insects, rely on colour vision for survival, using it to find food, avoid danger, and communicate. The ability to perceive different wavelengths of light is a remarkable adaptation that shapes how we interact with the world.
Understanding the Colour Spectrum
The colour spectrum, often called the visible spectrum, is the range of light wavelengths that the human eye can detect. This spectrum includes all the colours we see in a rainbow: red, orange, yellow, green, blue, indigo, and violet. Each colour corresponds to a specific wavelength, with red at the longer end and violet at the shorter end of the spectrum. The colour spectrum is a cornerstone of colour science, helping us understand how different colours are produced and perceived. In practical terms, the colour spectrum is used in everything from lighting design—where other colours can set the mood of a room—to digital technology, where screens blend different colours to create lifelike images. The ability to perceive and distinguish many different colours within the spectrum is fundamental to how we experience the world visually. Even in colour therapy, the colour spectrum is believed to influence our emotions and well-being. By understanding the visible range of light and how it interacts with the human eye, we can better appreciate the richness and variety of the colours that surround us every day.
The Role of the Human Eye
The human eye is the gateway to our experience of colour, playing a vital role in how we perceive the world. Light enters the eye and is focused onto the retina, a thin layer of tissue at the back of the eye. The retina contains millions of light-sensitive cells, including cone cells and rod cells. Cone cells are responsible for detecting colour and are most concentrated in the centre of the retina, allowing us to see fine details and vibrant hues. Rod cells, on the other hand, are more sensitive to low light levels and help us see in dim conditions, though they do not contribute to colour perception. While the human eye is capable of detecting a wide range of colours, it does have its limitations. For example, colour blindness occurs when one or more types of cone cells are missing or not functioning properly, making it difficult to distinguish certain colours. Individuals with these deficiencies are referred to as colour blind, as they are unable to perceive some colours accurately. Despite these challenges, the human eye remains an incredibly sophisticated organ, allowing us to experience the beauty and diversity of colour in our everyday lives.
Our Brains May 'Make Up' New Colours
Given these philosophical problems, researchers are pretty 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 cone types at the back of their eyes. These monkeys are functionally colour blind to red, as they lack the specific cone cell type sensitive to red wavelengths. 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 green-sensing cones to a new red-sensing cone cell type. This introduced a new cone type, allowing the monkeys to perceive more colours and distinguish colours they previously could not. The monkeys’ brains could not see red before, but once injected with the virus, they could 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 had a new phenomenological experience. They were able to see a colour that they hadn’t been able to see before. The addition of a new cone type enabled the perception of more colours. It allowed the monkeys to distinguish colours that were previously indistinguishable, similar to how some humans with extra cone types may see a broader spectrum. Once they had the visual apparatus to detect it, their brains 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 simultaneously. 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 mixtures, not a single pigment that is equally red and green or blue and yellow. Some colours, known as impossible colours, defy normal visual experience because our opponent neurons cannot process them as a single colour, highlighting the limitations of human colour perception. The concept of impossible colours challenges our understanding of colour perception and is addressed by two main theories: the trichromatic theory and the opponent process theory.
When it comes to yellow, most people agree on what constitutes pure yellow, even though subjective experiences may differ.
The Seventies and Eighties
In the 1970s, researchers thought the human brain couldn’t see true blue-yellow or red-green because of how 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 participants would always receive the same quantity of red and green light in their eyes. After some time staring at the photos, most 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 the results were phony, 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 can perceive new colours.
These findings raise an interesting question: how many colours can humans perceive? The number of distinct colour shades the human eye can detect is vast, but it can vary among individuals, especially those with colour vision impairments. Tools like Pantone are often used to organise and describe the wide range of colours we can see.
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 because we can’t remember visual novelty. We learned to perceive all the colours we will see by age one. It is not true of other senses. We taste new flavours all the time. For instance, if you had never tasted fennel before and tried it, you’ll experience it as something different from eating an orange. The same goes for sounds and even touch. Our brains create ways of instantly representing these experiences to our conscious selves. Why would colour perception be any different?
Colour Spaces and Technology
Colour spaces are essential tools in the world of technology and design, providing a framework for creating and reproducing colours across different media. A colour space is a mathematical model that defines how colours are represented, whether on a digital screen, in print, or in film. Common colour spaces include RGB (red, green, blue), which is used in digital displays, and CMYK (cyan, magenta, yellow, black), which is used in printing. Each colour space has its own strengths and limitations, influencing how colours appear in different contexts. One of the main challenges is accurately reproducing different colours across various devices and media, as each device may interpret and display colours differently. Advances in technology have made it possible to produce a vast range of colours with remarkable accuracy, thanks to precise control over the combination of lights or inks. Colour management software ensures that colours remain consistent across devices, which is especially important in industries like graphic design, fashion, and interior design. In film and video production, colour spaces are used for colour grading, allowing creators to craft specific moods and atmospheres. As technology continues to evolve, our ability to manipulate and experience colour becomes ever more sophisticated, shaping the way we see and interact with the world.
The Complexity of Colour
Colour is far more than just a visual experience—it’s a complex interplay between biology, psychology, and culture that shapes how we see and interpret the world. At the heart of human colour perception are the cone cells in our eyes, specialised light receptors that respond to different wavelengths of light. Most humans have three types of cone cells, each tuned to detect specific parts of the colour spectrum: one for red, one for green, and one for blue. This trichromatic system forms the foundation of our colour vision, allowing us to perceive a vast array of hues by blending signals from these different cone types.
However, not everyone experiences colour in the same way. Individual differences in the number and sensitivity of cone cells can lead to variations in colour vision. For example, people with red-green colour blindness have difficulty distinguishing between these two colours because of differences in their cone cells’ ability to detect certain wavelengths of light. These variations highlight how the biology of the human eye can shape our unique perceptions of the world around us.
Lighting conditions also play a crucial role in how we perceive colour. Under brighter light, our cone cells are more active, making colours appear more vivid and distinct. In dimmer environments, our ability to perceive colour fades, and the world can seem washed out or grey. The colour spectrum itself—ranging from warm colours like red, orange, and yellow to cool shades of green and blue—reflects the different wavelengths of light that our eyes can detect. The way we categorise and interpret these colours can be influenced by cultural background, language, and even personal experience, leading to a rich diversity of colour categories and associations across the globe.
The opponent process theory adds another layer to our understanding, suggesting that our brains interpret colour by comparing the activity of different types of cone cells. This helps explain why certain colour combinations, like blue and yellow or red and green, are perceived as opposites and why some shades are more difficult to distinguish.
Colour science, the study of how we perceive and interpret colour, has practical applications in everything from art and design to marketing and technology. Tools like colour spaces help designers and engineers create visuals that are consistent and appealing across different devices and media. Meanwhile, research into colour perception continues to reveal just how varied and complex our experiences of colour can be.
Humans aren’t the only creatures with sophisticated colour vision. In the animal kingdom, many species have evolved their unique ways of seeing the world. Some birds, for example, have four types of cone cells, allowing them to perceive colours beyond the range visible to most humans. These differences in colour vision across species underscore the evolutionary importance of being able to detect and respond to different wavelengths of light, whether it’s spotting ripe fruit, avoiding predators, or finding a mate.
Ultimately, the complexity of colour lies in the intricate dance between our eyes, our brains, and the world around us. From the basic biology of light receptors to the cultural meanings we attach to different shades, colour perception is a vivid reminder of how diverse and fascinating our experience of the world can be. As our understanding of colour science grows, so too does our appreciation for the subtle variations and endless possibilities that colour brings to our lives.
How Do We Respond To Colours?
Even if we perceive colours differently, researchers think we respond to them emotionally similarly—something we discuss in this post. Colour stimulates specific cone cells in the retina, sending signals through neural pathways to the brain, which interprets these signals and leads to emotional responses. 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 warmer colours, including oranges, are processed more intensely by the human eye, which allows us to perceive more variations in these hues. These responses appear to be evolutionary. Humans have them, but so do other mammals, fish and even single-celled organisms to optimise 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. Brighter light enhances our ability to perceive colours vividly by activating specific photoreceptor cells in the eyes. Researchers hypothesise that life is less busy during the middle of the day because of UV and at night because of predators. Interestingly, it doesn’t seem to matter how organisms detect blue or yellow light through eyes, light-sensitive patches or light-detecting organelles. In each case, their behaviour is similar. They become active in the morning and evening, whereas when it is night or the middle of the day, they are less active. Colour, rather than light intensity, could be what primarily drives tiredness—melanopsin receptors in the eye gauge blue or yellow light, influencing emotional responses and circadian rhythms.
Knowledge Affects The Colours That We Perceive
What you think about the world also changes how you perceive colour. Say, for instance, you meet somebody who looks pale. Without some form of knowledge (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. In dim light or very low light levels, rods in the retina become more active, and colour perception diminishes because cones require brighter illumination to function. When participants examined objects in this environment, they could still recognise what they were—a strawberry was a strawberry—but they didn’t feel like eating it. Furthermore, other study participants looked sick and ill. Peripheral vision is less sensitive to colour, which can further affect how we perceive objects in challenging lighting conditions. Researchers hypothesised that the colour change violated the participants’ knowledge of how specific objects should appear. Differences in perceptions were particularly apparent regarding evolutionarily imperative things like food and other people. Participants were often willing to eat foods in normal light but not so keen on the yellow light. Similarly, most participants looked attractive in normal light, but in colour-distorted light, they were less appealing. Research like this might explain our visceral reactions to red faces or pale skin. We associate them with things like anger, embarrassment, illness and disease. In evolutionary terms, seeing in full colour was advantageous because it allowed us to navigate our environment better. 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 examine whether our brains respond to colours similarly. This approach doesn’t deal with Chalmers’ complex 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 similarly. Researchers used magnetoencephalography techniques to study the electrical patterns of volunteers’ brains after exposing them to various colour images. Colour stimulates specific neural pathways, leading to consistent patterns of brain activity across individuals. 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 such a thing as a red or blue signature exists in the brain. However, each brain was slightly different. Researchers then asked whether the relationships one perceives between colours differ from those of another. So, is it the same way one person relates pink and red as somebody else? It turns out that 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 experience of those colours is the same cannot be proven. However, researchers now think that the brain consistently forms relationships between colours and people based on neural activity.
Do We See The Same Colours?
Given the philosophical problems outlined above, we probably won’t know whether we see the same colours. The broad body of research suggests that we probably see approximations of what others see. There are differences in the rods and cones in our eyes. Most humans have three types of cone cells, which allow most people with normal colour vision to perceive around one million colours. The brain structures responsible for visual processing likely cause differences, too. This variation is evident when you ask people to select their best example of a particular colour. Researchers find that we typically disagree on what shade is the most red or the most green. These differences reflect the influence of colour categories and raise the question of how many colours humans can perceive. For some, most reds will look scarlet, while it will be salmon pink for others.
Furthermore, researchers don’t seem to be able to determine 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 critical. There may also be differences in how 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 broader spectrum of colours, running more into the infrared and ultraviolet. Genetic variations can enable some individuals to see more colours than others.
The Difference Between Men & Women
Around 40 per cent of women may have a 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 suggests that this type of vision is actual, 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. Colour blindness, most commonly red-green colour blindness, is a genetic condition that affects the ability to distinguish certain colours due to differences in cone cell types and neural processing. Most mammals, by contrast, have only two or three types of cone cells, which limits their colour perception compared to humans with more cone types. 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 yet. But we now know more than ever about the brain, colour perception and why we see the way we do.
