Our colour vision results from the fact that our eyes contain three types of light-sensitive cells or cones that have different wavelength sensitivity. Some people (called anomalous trichromats) are colour blind and this is usually because one of their cones is mutated and has a different wavelength sensitivity compared with those in so-called normal observers. Colour-blind is a misnomer really because anomalous trichromats can still see colour; they just have less ability to discriminate between colours than normals. Some people are missing one of the cone classes altogether and are referred to as dichromats; they have even poorer colour discrimination but can still see colour. Only monochromats are really colour blind and they are extremely rare.
For a long time I have known that some females have four cones classes (this makes them tetrachromats). Dr Gabriele Jordan, a researcher at the Institute of Neuroscience (Newcastle University) has spent the last 20 years working on human colour vision. She has discovered that tetrachromatic females exist and that although this gives them the potential for colour discrimination much better than normal trichromats in practice most have normal colour discrimination. However, in a recent report she has found a tetrachromat who really does have enhanced colour discrimination. This is really exciting news!
The report in the Daily Mail suggest that a functional tetrachromat could be able to see 99 million more hues than the average person. Personally I am skeptical of this claim even if, as I suspect, it means 99 million more hues than the average person. The number of colours that an average person can see is debatable but I think may be about 10 million (see my previous blog post).
Last year a student, Kaori, from Japan spent some time with me at Leeds and we spoke a lot about how to use colour effectively in maps and in urban design generally. One of the issues we were looking at was whether the maps’ features would be discriminable to colour-blind observers (of which, of course, there are many). So I was interested to come across an interesting article today relating to this very issue.
Apparently the following image appeared in the Guardian newspaper:
It’s a colour-coded map of London. It shows areas of deprivation with red being the most deprived. It met with much criticism, however, and many people said they had difficulty in discriminating between the colours. Of course, colour-blind observers most commonly have difficulty discriminating in the red-green region of colour space. The company who made the map engaged in a debate with users on twitter and created variously different coloured versions of the map, subjecting each to the public vote via twitter. The map below is one of the later versions.
For further details please refer to the story at The Guardian here.
About 8% of men are colour blind. In the past I have written about how designers may not adequately take this into account effectively ignoring 4% of the population. I also wrote about how in Korea the problem of traffic lights for colour blind people was being addressed by using different shapes for the different colours.
Now I am interested to hear about a development from Japan – Professor Ochiai at Kyushu Sangyo University has developed a clever modification that is not noticed by people with normal colour vision but helps those who are colour blind. Before the introduction of LED lights people often could tell red from green by the difference in brightness. But LED lights are so bright that they look rather similar in brightness, and for someone with red-green colour blindness they may look identical. Professor Ochiai has added a blue cross to the red light which is very visible to colour-blind observers but can hardly be noticed by the rest of us. Very clever!!
The new lights are being tested in Fukuoka and are due to go on test in Tokyo soon.
Colour blindness is mainly a male affliction. Something like 8% of all men in the world are colour blind though, as I have mentioned before, this doesn’t mean that they cannot see colour but, rather, means that their colour discrimination is not as good as that of so-called normal observers (the rest of us, in common vernacular). See my earlier post. So we normally think of colour blindness as being something undesirable, something that ideally we would like to be able to cure.
Interesting then that new research at Anglia Ruskin University has suggested that colour blindness may even be an advantage. The study was led by Dr Andrew Smith and showed that colour-blind monkeys (tamarins, to be exact) were better than their ‘normal’ counter-parts at catching camouflaged insects (such as crickets). I guess what this means is that the camouflage is designed (I guess I should say, has evolved) to be effective when viewed by normal tamarins. So the colour-blind tamarins may be better off in some sense.
Dr Smith is also quoted as saying that there is some evidence that, in humans, dichromats (who have two classes of cone rather than three) may see better in dim light than trichromats. For further information see http://www.businessweekly.co.uk/academia-a-research/13403-colour-blind-monkeys-have-advantage-in-catching-camouflaged-prey.
I was recently writing about colour blindness in the context of design and noted that most colour blind people see colour – it’s just they have poor discrimination and some colours look the same to them whereas to a so-called normal observers they would look different.
People who don’t see colour at all are rare. But I was just reading about one, Neil Harbisson, a classically trained pianist who has been colour blind since birth. He suffers from a condition called Achromatopsia which means he can only see the world in grey. However, he has recently being used a piece of technology that allows him to hear variations in colours. The eyeborg helps translate colours into sound and transforms the colour information picked up by the built-in camera into sound frequencies. For example, when he looks at a red, for example, he hears an F (= 349.23Hz); if he sees a yellow he hears a G. For more information see http://www.techeye.net/science/technology-helps-man-hear-colours.
I wonder what this would feel like. Of course, synesthesia sometimes occurs naturally. That is, some people can hear colours, see sounds, taste numbers etc. I sometimes think that Kandinsky (the artist who worked at the Bauhaus) may have been synesthesic because of his interest in the relationship between colour and shape. Quite possibly, sensing the world in a way that is different to how most people perceive it may me an advantage to an artist.
Is colour blindness a problem in design? Colour blind is rare amongst females but is very common amongst males. Approximately 8% of all the men in the world have some form of colour blindness. Colour blindness is a bit of a misnomer of colour; most colour-blind people can see colour but confuse colours that so-called normal observers can easily distinguish between. The most common case is red-green colour blindness and such sufferers find it hard to tell reds and greens apart.
But does design take this into account sufficiently? One area where there may be a problem is in the gaming industry. I came across the following comment today where someone is reporting a problem using Call of Duty (a game I don;t play but which I understand is quite popular) on the Xbox. Apparently, the Gamertags of all the players are either green if they are on your team, or red if they are an enemy. Oops!! I wonder how much of a problem this is. The problem is probably greatest when colour is used to convey information (as in this case, friend or enemy) rather just for aesthetics (where the information may be conveyed by contrast alone).
Colour blindness afflicts about 1 in 12 men in the world. Women are far less affected because they have two X chromosomes. Men only have one X chromosome and therefore there is no backup if the gene for good colour vision is damaged or changed. Of course, colour blindness is a misnomer. Very few people indeed are really colour blind and the term colour defective is scientifically more correct. So-called colour blind people have trouble discriminating between colours that the rest of us see as different. Most commonly the difficult is in telling reds and greens apart which is where the term red-green colour blind derives from. Though people need to be able to pass colour-vision test before they can be employed in certain professions (such as being an aeroplane pilot) where colour decisions are critical, everyone is allowed to drive a car. Even though traffic lights are red and green!!
The argument for allowing colour blind people to drive has always been, I think, that drivers quickly learn the positions of lights. Red, is on top, amber in the middle and green on the bottom. However, is that red-amber-green order used everywhere in the world. It is used in the UK where I live. But elsewhere?
Whether to do with the order of the lights or not, several studies have shown that colour blindness is a risk factor in driving. Hence the development of the UniSignal (Universal Signal Light). Developed in South Korea the UniSignal uses different shapes for different colours so that drivers can recognise which light is on whatever the order in the particular city in which they find themselves.
Kandinsky would approve!