In Plain Sight: Colour Blind Awareness

12 minutes ago
5 min read

Do We All See the Same Thing?

Understanding Colour Blindness

Red. Green. Blue. Purple. Colour is so woven into everyday life that most of us barely think about it. We use it to choose clothes, read maps, understand charts, follow signs, watch sports and even tell whether something is safe or dangerous.

But what if the colours you see aren't quite the same as the colours someone else sees?

For Colour Blind Awareness Day on 6 September, we're taking a closer look at colour blindness, or, more accurately, colour vision deficiency (CVD), what it actually means, how common it is and why something as simple as the way we use colour can make a surprisingly big difference.

First things first: does colour blind mean seeing in black and white?

Usually, no. The term colour blindness can be misleading. Most people with colour vision deficiency can see colour; they simply perceive some colours differently or find particular colours and shades difficult to distinguish from one another. Different types of CVD affect colour perception in different ways.

Red-green colour vision deficiencies are the most common. Depending on the type, colours such as red, green, brown, orange, blue and purple can become harder to distinguish from one another. A much rarer blue-yellow deficiency can make blues and greens difficult to distinguish and affect the perception of yellow.

So there isn't one universal answer to the question “What does a colour-blind person see?”

Two people with colour vision deficiency may experience colour quite differently.

It's much more common than you might think

Perhaps the most surprising thing about CVD is just how many people it affects. Inherited red-green colour vision deficiency affects around 1 in 12 males, while it is considerably less common in females. Colour Blind Awareness estimates that statistically at least one child in every average UK classroom will have some form of colour vision deficiency.

Why the big difference between males and females? The most common inherited forms are associated with the X chromosome. Because males have one X chromosome while females have two, an affected gene is much more likely to result in CVD in males. And while many people are born with colour vision deficiency, it isn't always inherited. Changes in colour vision can sometimes develop later in life as a result of certain eye or other health conditions, injuries, stroke or some medicines.

When colour becomes information

This is where colour vision deficiency becomes particularly interesting.

Think about how often we don't just use colour because something looks nice — we use colour to communicate.

🔴 Red means stop.🟢 Green means go.

A graph might use red, amber and green to show performance. A map might identify different routes entirely by colour. A website might turn a box green when something is available and red when it isn't.

At school, a teacher might say “look at the information highlighted in green.” At a football match, two teams might be wearing kits that appear completely different to most spectators but are much harder to distinguish for somebody with CVD.

The problem isn't necessarily the colour itself. The problem comes when colour is the only clue.

Colour Blind Awareness recommends combining colour with things such as words, labels, symbols, patterns and strong contrast, so important information isn't dependent on somebody being able to distinguish one colour from another.

There's a simple test for our own designs

This was one of our favourite pieces of advice while researching this article. Take a graphic, chart, website page or piece of information and view it in greyscale. Does it still make sense? Can you still identify everything you need to know without the colours? If the answer is no, Colour Blind Awareness suggests the design may need another way of communicating that information. It's a remarkably simple reminder that good accessible design doesn't necessarily mean abandoning colour. It means not asking colour to do all the work.

What about children?

Colour vision deficiency can easily go unnoticed. The NHS says signs in children can include difficulty with colour-sorting activities or using unexpected colours when drawing and painting. Colour vision tests are usually carried out in older children if a problem is suspected. And that matters because so much educational material relies on colour. Charts. Maps. Diagrams. Worksheets. Science experiments. Sports kits. Classroom displays.

A child struggling with a colour-coded task may simply not be receiving the same visual information as everybody else. If a child has diagnosed CVD, the NHS recommends letting their school know so appropriate adjustments can be made to lessons and exams where necessary.

Can colour blindness be tested?

Yes. Two of the main methods used to investigate colour vision deficiency are Ishihara tests: those familiar images made from coloured dots containing numbers or shapes, and colour-arrangement tests, where colours are placed in order according to shade. You'll find plenty of colour-blindness tests online, but they shouldn't be treated as a diagnosis.

The NHS advises getting checked by an optician if you have concerns about your own or your child's colour vision. Colour vision testing isn't automatically included as part of a routine NHS sight test, but it can be requested. And if your colour vision changes unexpectedly, rather than having always been that way, that's another good reason to seek professional advice because acquired colour vision deficiency can have an underlying cause.

Seeing things differently

Colour Blind Awareness Day isn't really about imagining a world without colour. It's about recognising that colour doesn't communicate in exactly the same way to everybody. For most people with colour vision deficiency, it is simply part of how they see the world and something they adapt to very well.

But for the rest of us, particularly when we're designing signs, websites, charts, classrooms, workplaces or social media, there's something useful to take away from that.

Use colour. Enjoy colour. Just don't rely on colour alone.

Because good design shouldn't depend on everyone seeing exactly the same thing.