What is Colour Blindness?

As mentioned in the summary of my previous project, I would like to research into the effects of colour blindness on colour differentiation in games. I need to learn more about this condition and how it can be considered when designing UI to be more inclusive.

What is Colour Blindness?

Dictionary.com defines colour blindness as: 
The 'inability to distinguish one or several chromatic colours, independent of the capacity for distinguishing light and shade'. ⁽¹⁾

Gamasutra states that 'colour is perceived by the brain as a result of light rays reflecting off objects and hitting the retina of the eye. However, different colours can have different biological effects and not all people see colour the same'. ⁽²⁾

How Does Colour Blindness Work?

'In the [eye's] retina, there are two types of cells that detect light. They are called rods and cones. Rods detect only light and dark and are very sensitive to low light levels. Cone cells detect colour and are concentrated near the centre of your vision. There are three types of cones that see colour: red, green and blue. The brain uses input from these cone cells to determine our colour perception.

Colour blindness can happen when one or more of the colour cone cells are absent, not working or detect a different colour than normal. Severe colour blindness occurs when all three cone cells are absent. Mild colour blindness happens when all three cone cells are present but one cone cell does not work right'. ⁽⁴⁾ 

Types of Colour Blindness

There are multiple types of colour blindness in which specific colour perceptions vary. 

Trichromacy is classed as 'normal vision [and] uses all three types of light cones correctly'. ⁽³⁾ 

Dichromacy is where 'only two types of light cones are able to perceive colour'. ⁽³⁾ 

The image below shows the comparison between trichromats (people with normal vision) and dichromats (people with colour blindness).

Deuteranopia

Deuteranopes are more likely to confuse:
1. mid reds with mid greens
2. blue greens with grey and mid pinks
3. bright greens with yellows
4. pale pinks with light grey
5. mid reds with mid browns
6. light blues with lilac

Protanopia

Protanopes are more likely to confuse:
1. black with many shades of red
2. dark brown with dark green, dark orange and dark red
3. some blues with some reds, purples and dark pinks
4. mid greens with some oranges

Tritanopia

Tritanopes are more likely to confuse:
1. light blues with greys
2. dark purples with black
3. mid greens with blues
4. oranges with reds

Monochromia

The image above shows an extremely rare condition known as Monochromacy (Achromatopsia), in which a person 'can see no colour at all and their world consists of different shades of grey ranging from black to white. Achromatopsia is extremely rare, occurring only in approximately 1 in 33,000 and its symptoms can make life very difficult. Usually someone with achromatopsia will need to wear dark glasses inside in normal light conditions'. ⁽³⁾

References 

(1) Dictionary. (2020). Colour Blindness. 
Available: https://www.dictionary.com/browse/color-blindness?s=t.
Last accessed 1st Nov 2020.

(2) Herman Tulleken. (2015). Color in Games: an in-depth look at one of game design's most useful tools. 
Available: https://www.gamasutra.com/blogs/HermanTulleken/20150729/249761/Color_in_games_An_indepth_look_at_one_of_game_designs_most_useful_tools.php#:~:text=The%20Function%20of%20Color%20in,them%20easier%20in%20the%20game.
Last accessed 1st Nov 2020.

(3) Colour Blind Awareness. (2020). Types of Colour Blindness. 
Available: https://www.colourblindawareness.org/colour-blindness/types-of-colour-blindness/.
Last accessed 1st Nov 2020.

(4) David Turbert. (2019). What Is Color Blindness?. 
Available: https://www.aao.org/eye-health/diseases/what-is-color-blindness#:~:text=Color%20blindness%20occurs%20when%20you,and%20reds%2C%20and%20occasionally%20blues. 
Last accessed 1st Nov 2020.