There's an interesting aspect of colour that this article doesn't cover, which is the psychological primaries (<a href="https://en.wikipedia.org/wiki/Primary_color#Psychological_primaries" rel="nofollow">https://en.wikipedia.org/wiki/Primary_color#Psychological_pr...</a>).<p>The eye gets colour information from the three types of cone, but it then processes this information into three new dimensions. Black against white, red against green, yellow against blue. So from a psychological point of view there are four primary colours: RYGB.<p>These are arranged like the points on a compassb so it's impossible to experience a mix of red and green or yellow and blue, just like it's impossible to be both north and south.<p>I think this is why these colours tend to be used more often in logos and board game pieces. The brain views them as more simple, and the psychological secodary colours (orange, chartreuse, turquoise and purple) as more complex.