Colour is a fascinating aspect of our visual experience. The myriad hues, tints, and shades that infuse our world provide endless nuance and variety. Yet despite its ubiquity, the origins and perceptions of colour have long captivated scientists and philosophers alike. In this article, we will explore some intriguing questions around colour, including how it is produced, how many colours exist, and even how it relates to our sense of self.
What Is Colour?
To understand colour, we must first consider light. Visible light consists of electromagnetic waves of different wavelengths. The wavelengths we can see range from about 400 to 700 nanometers (nm). The longest wavelengths appear red, grading through orange, yellow, green, blue, and violet as the wavelengths get shorter. White light contains all wavelengths of the visible spectrum mixed together. But if white light passes through a prism, the wavelengths separate into their component colours, producing the rainbow spectrum.
When light hits an object, some wavelengths are absorbed while others are reflected. The reflected wavelengths determine the colour we see. A red rose absorbs most of the spectrum, reflecting back mostly long red wavelengths. A blue iris absorbs the warmer red through yellow tones, leaving cooler blues to be reflected and seen.
Within the eye, light passes through the cornea and lens and falls on the retina. The retina contains specialised photoreceptor cells called rods and cones. Cones are responsible for colour vision. There are three types of cones that are each sensitive to different wavelengths corresponding to red, green, or blue light. Signals from the cones converge and are processed by retinal ganglion cells. Axons from the ganglion cells make up the optic nerve carrying visual information to the brain.
In the visual cortex of the brain, we have neural wiring that allows us to perceive colour based on the signals from the cones. Complex processing determines hue, saturation, brightness and our subjective experience of colour.
How Many Colours Are There?
There are a few ways we can approach the question of how many colours exist:
- Visible spectrum – There are about 100 discernible hues in the visible light spectrum. Red, orange, yellow, green, blue, violet and all the gradations between them can be distinguished by the normal human eye.
- Colour wheel – Traditional colour wheels contain between 12 main colours to 24 segmented colours. These include the primary colours (red, yellow, blue), secondary colours (orange, green, purple), and sometimes tertiary colours between them.
- Computer screens – Displays like computer screens create colours by mixing varying intensities of red, green and blue light. True colour displays use 24-bit colour depth, yielding about 16.7 million possible colour combinations.
- Printed colours – For ink on paper, traditional CMYK printing uses 4 colour inks – cyan, magenta, yellow and black. Mixing these inks in varying amounts can reproduce up to millions of colours as well. Modern digital printers may use even more ink colours.
- Nameable colours – Studies suggest the average person can consistently identify between 10 and 20 basic colour terms like red, green, blue and name thousands of other hues by combination, like light green or purplish-red.
- Discernible colours – Some estimates place the number of colours most people can theoretically distinguish in optimal lighting conditions to be around 10 million. This is due to factors like varying hue, chroma, brightness, and colour blindness.
So in summary, while the visible spectrum itself contains about 100 saturated hues, when variations in shade, tint, tone, and brightness are accounted for, we can perceive somewhere between 2 million to 10 million distinct colours!
How Many Colours Can the Human Eye See?
The human eye contains photoreceptor cones capable of detecting wavelengths of light corresponding to red, green and blue. Signals from these cones are processed by the brain to discriminate colour. So in theory, the eye sees colours through a type of built-in “RGB” filtering and coding system.
This means the eye can register approximately 10 million different colours. This range takes into account differences not just in the hue itself, but also in saturation, brightness and contrast levels. In optimal lighting conditions, the average person can differentiate this many distinct shades and tones based on the processing of cone cell signals to the brain.
However, there are some caveats. Extremely saturated colours may appear indistinct from one another. On the other end, colours with very low saturation or contrast may be hard to discern from grey shades. And someone with colour blindness will have difficulty distinguishing certain hues depending on their type of vision deficiency.
While the human eye is amazing at analysing a wide gamut of colour, it doesn’t quite compare to the mantis shrimp. This marine creature has 12 types of cone cells, so they can potentially detect over 10 billion colours! That puts even our 10 million to shame.
How Many Colour Names Are There?
While we can see millions of distinct colours, we categorise and name them using a surprisingly small set of colour terms. Studies of cultures and languages around the world have found the average number of basic colour terms in a language is between 5 and 20.
Researchers Berlin and Kay studied colour naming across 98 languages and found the number of colour names emerges progressively:
| Number of colour terms | Example colours |
| 2 | Black, white |
| 3 | Red, black, white |
| 4 | Green, red, black, white |
| 5 | Blue, green, red, black, white |
| 6 | Yellow, blue, green, red, black, white |
| 7-11 | Orange, purple, pink, grey, brown added |
While basic colour terms number under 20 for most cultures, people are still able to describe and discuss more nuanced variations by using descriptive phrases, like “light green” or “reddish orange”. Some estimates place the number of named colours in English at around 4,000 to 10,000!
The indulgent proliferation of fancy colour names in paint brands has certainly expanded named colours well beyond the basics. With artistic combinations like “first blush” and “elephant’s breath”, there may be no limit to imagined colour descriptions.
How Are Colours Categorised?
While individual colour names number in the thousands, they can be grouped into common categories based on shared properties:
- Primary colours – Red, yellow and blue. These are the core colours that can be mixed to create all other hues.
- Secondary colours – Purple, orange, green. These are created by mixing two primary colours.
- Tertiary colours – Intermediate hues between the primary and secondary colours, like red-orange or blue-violet.
- Warm colours – Red, yellow, orange. These are colours associated with heat, fire and sunlight.
- Cool colours – Blue, green, purple. These are linked with water, sky and shade.
- Neutrals – Black, white, grey, brown. These lack strong hue and can modulate other colours.
Colours are also categorised by attributes like:
- Hue – The dominant wavelength of the colour, such as blue, orange or green.
- Chroma – Colourfulness and intensity of hue, from low (muted) to high (vivid).
- Value – Lightness or darkness of the colour, ranging from light to dark.
- Shade – A colour mixed with black, making it darker.
- Tint – A colour mixed with white, making it lighter.
- Tone – A hue mixed with grey, modulating its chroma.
These attributes allow us to place colours into a comprehensive colour space and map relationships between them. Digital colour models like RGB and CMYK rely on such colour theory to replicate the wide gamut of hues we can perceive.
How Do Colours Affect Us Psychologically?
Colours have a significant psychological impact and can evoke strong reactions. While effects vary by culture and the individual, some general colour associations include:
- Red – Passion, excitement, danger
- Orange – Cheerfulness, creativity
- Yellow – Happiness, optimism
- Green – Peace, growth, health
- Blue – Calm, stability, professionalism
- Purple – Royalty, luxury, mystery
- Pink – Sweetness, femininity
- Black – Power, sophistication
Colours can impact our moods, energy levels, productivity and behavior patterns. Warm hues like red and yellow tend to be energising, while cool blues and greens are more relaxing. Understanding colour psychology allows designers and marketers to strategically employ colour to evoke desired responses.
How Are Colours Perceived Across Cultures?
While colour associations can be quite culture-specific, some broad patterns occur:
- Red signifies passion, danger and importance across many cultures.
- White is linked with purity and peace, especially in Western and Eastern cultures.
- Black denotes formality and elegance, but also evil in some Western and African cultures.
- Blue represents calm and order in Western cultures, but grief and misfortune in parts of Asia.
- Green recalls nature and life cross-culturally, but wealth and prosperity in some Asian cultures.
- Yellow is cheerful and auspicious in much of the Americas and Europe, but ominous in parts of Asia.
Understanding how colour meanings differ among global audiences is vital for designers and marketers aiming to maximise appeal and minimise offence. Allowing for colour preferences and symbolism during the creative process can lead to more positive perceptions.
How Does Colour Relate to Personality?
Research suggests colour preferences provide insight into personality:
- Red – Confident, competitive, energetic
- Orange – Social, creative, optimistic
- Yellow – Cheerful, intellectual, idealistic
- Green – Calm, traditional, focused on security
- Blue – Loyal, quiet, peace-seeking
- Purple – Artistic, wise, individualistic
- Black – Sophisticated, rebellious, stoic
While not universally true, we often gravitate to hues reflecting our traits and temperaments. Colour psychology forms the premise of personality colour tests. Figuring out someone’s preferred hues can provide clues to their outlook, thinking style and behaviours. But as with all personality frameworks, it represents general patterns rather than firm predictions.
How Do Our Colour Preferences Change With Age?
Studies reveal some trends in how colour preferences evolve across the lifespan:
- Babies – high contrast, sharp edges, bright primary colours like red, yellow and blue
- Young children – expand to more colours, drawn to rainbow brightness
- Older children – favour intense, saturated colours
- Teens – muted, darker, unconventional colour choices
- Young adults – widely varied preferences
- Middle age – return to more saturated reds, blues, greens
- Elderly – soft, desaturated colours easier on the eyes
Of course, environmental and cultural factors also shape colour tastes. But in general, as we mature, our colour sensibilities shift from bold primaries to subtler shades better suited to aging vision and temperament.
How Does Colour Affect Learning?
Research into colour psychology and learning styles provides some suggestions on effectively using colour to enhance learning and retention:
- Blue tones are calming and aid concentration.
- Green promotes harmony and focus.
- Yellow boosts alertness and memory.
- Red energises but can be distracting.
- Avoid black backgrounds as they strain the eyes.
- Use warm tones for subjects requiring energy.
- Use cool tones for cerebral or technical subjects.
- Avoid excess colour variation on the page.
Matching colour strategies to content, goals and learners’ needs can improve educational outcomes. But effects will vary – what energises one student may distract another. The key is flexible application of colour principles.
How Can Colour Affect Productivity?
Workplace colour schemes influence mental clarity, focus and motivation. Cool blues and greens promote calm concentration. Warm reds and oranges boost energy and stimulation. Neutrals like grey offer flexibility. Recommendations include:
- Paint focus work areas blue to aid concentration.
- Choose green for spaces needing balance and harmony.
- Add yellow to break areas to stimulate creativity.
- Use reds in moderation to energise sluggish workers.
- Pick grey or neutral shades for flexible spaces.
- Highlight key areas with vibrant colours to draw attention.
A thoughtful colour plan considering psychological factors can enhance workplace efficiency. But beware extremes. Overuse of reds or yellows may hinder focus, while too much blue could lower motivation. Remember that reactions are subjective when customising colour schemes.
Conclusion
Our exploration reveals colour is complex, contextual and fascinating. While the eye can discern millions of hues, we codify them into a few basic colour terms. Cultural influences, individual psychology and practical applications all shape our colour perceptions and preferences. No single answer captures the richness behind the question “How many colours are there?” Perhaps it is the myriad possibilities within colour that make it so integral to human life and experience.
