How colours get their names

Ever wondered why colours are always named in a specific order worldwide? It may be due to how our eyes work, says a new study.

These findings, appeared in the journal Proceedings of the National Academy of Sciences, suggest that wavelengths of colour that are easier to see also get names earlier in the evolution of a culture.

Whether we all see the world the same way has long been a common question in philosophy. One strategy for investigating the question is to see what colours get names in different cultures. 

It’s also been found that colour names always seem to appear in a specific order of importance across cultures — black, white, red, green, yellow and blue. “For example, if a population has a name for red, it also has a name for black and for white; or, if it has a name for green, it also has a name for red,” said researcher Francesca Tria, a physicist at the ISI Foundation in Turin, Italy.

But if a population has a name for black and white, that doesn’t necessarily mean they have a name for red, she was quoted as saying by LiveScience.

To solve the puzzle of color-name hierarchy, Tria and her team developed a computer simulation with pairs of virtual people or “agents” who lacked the knowledge of colours.

One agent, the speaker, is shown two or more objects, invents a name for a colour to describe one of the objects, and refers to the item by that colour. The other agent, the hearer, then has to guess which item, and thus colour, the speaker referred to.

Scientists repeated this until all the agents came to a consensus on colour names.

A key feature of this simulation was its adherence to the limits of human vision. Our eyes are more sensitive to some wavelengths of light, or colours, than others. The agents in the simulation were not required to distinguish between hues that a human eye could not tell apart.

“Roughly speaking, human eyes can tell apart two colours only if their wavelengths differ at least by a certain amount — the just noticeable difference,” Tria said.

The researchers found the time agents needed to reach consensus on a colour name fell into a distinct hierarchy — red, magenta-red, violet, green-yellow, blue, orange and cyan, in that order.

This hierarchy approximately matches the colour name order seen in real cultures. This hierarchy of colours also matches the limits of human vision, with the human eye being more sensitive to red wavelengths than those for blue, and so on.

“Our approach suggests a possible route to the emergence of hierarchical colour categories,” Tria said.