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Fifty Shades of Grue

The intimate relationship between language and color perception

When you look at a rainbow, you see colored bands of light. In grade school, you probably learned the acronym ROY G. BIV—red, orange, yellow, green, blue, indigo, and violet. The first five and the last are, of course, familiar colors. But if you’re like me, you’ve never, ever, named the color of any other object as “indigo.”

The visible light spectrum is continuous and doesn’t naturally break up into distinct color bands. Nevertheless, we see distinct regions of different colors, suggesting that our perception of color is categorical. This observation raises the question: Are the distinct colors we see and can name with words like “red” and “blue” a product of innate perceptual processes or of learned linguistic categories?

Colours of the visible light spectrum
Colors of the visible light spectrum
Meganbeckett27 - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons

In a survey of color terms in languages around the world, anthropologist Brent Berlin and linguist Paul Kay found that different languages have different numbers of basic color terms. In fact, some languages only distinguish two color categories, corresponding to what we would call the “warm colors” of the red-yellow region of the spectrum and the “cool colors” of the blue-green region.

Although the colors of the visible light spectrum vary along a continuum, our visual system is maximally sensitive to four specific regions—red, green, yellow, and blue—which we then perceive as the four focal colors. Languages around the world tend to organize their color systems around these four focal colors. That is, languages will have names for these four colors before they’ll have basic terms for colors like orange or purple. This four-color distinction is an important element of Westernized global color schemes, as for example in the four suits of an Uno deck or in the logos for Microsoft and Google.

Diagram of the opponent process
Light coming into the eye is first sorted as red, green, or blue, and then as red-green and blue-yellow opponent colors.
Googolplexbyte - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons

Not all languages distinguish all four focal colors. In fact, it’s not uncommon among languages to have a single basic color term that includes both blue and green, a color category that researchers call grue.

The Japanese word ao is a good example of grue because it can refer to the color of grass or the color of the sky. And since the Japanese words for “leaf” and “tooth” are homophones, the word aoba can mean either “Greenleaf” or “Bluetooth,” depending on the context.1

You may wonder how Japanese speakers can use the same word to refer to both green and blue. However, Russian speakers are equally surprised to learn that English uses the same color term, blue, to refer to what they regard as two separate color categories. Russian distinguishes between goluboy, or “light blue,” and siniy, or “dark blue.” Native speakers of Russian are quite consistent about which shades of blue go in each category. Greek and Turkish make a similar light blue-dark blue distinction.

Four shades of grue
Four shades of grue, in three different languages.
Author created

When people are asked to sort color swatches, they tend to do so according to the color terms of their language. But even speakers of a grue language can sort swatches into blue and green piles when given focal green and blue swatches as models. In other words, they can clearly see the difference—after all, this distinction is made at a very early stage in color perception. It’s just that they don’t pay attention to the difference unless they need to.

The color terms of our language also influence our memory for color. Let’s say you show people a color swatch near the green-blue boundary. Later, you ask them to pick out the color they had seen from a set of similar swatches. Speakers of a green-blue language will be more accurate at this task compared with grue language speakers. This is because the words of our language provide memory “hooks” that aid in later recall.

In the spirit of the Fifty Shades of Grey mania currently sweeping the country, let me conclude with the following remark: Cross-linguistic research on color perception shows us that the language we speak doesn’t bind us to a particular world view, but it does dominate the way we perceive and think about our experiences. As for the S&M, I don’t even want to go there.


1If you know Japanese, you’re no doubt shouting: “But what about midori?” Japanese does have a color term that covers the standard range of green on the visible spectrum. In other words, midori means “green, not blue.” However, Japanese doesn’t have a complimentary term meaning “blue, not green.” Meanwhile, ao covers the whole green-blue range of the spectrum. Messy data such as these attest to the fact that languages are evolved structures and definitely not intelligently designed.


Berlin, B. & Kay, P. (1969). Basic color terms: Their universality and evolution. Berkeley: University of California Press.

Da Pos, O., & Albertazzi, L. (2010). It is in the nature of colors. Seeing and Perceiving, 23, 39–73.

Delgado, A. R. (2004). Order in Spanish colour words: Evidence against linguistic relativity. British Journal of Psychology, 95, 81–90.

Kay, P. & Maffi, L. (1999). Color appearance and the emergence and evolution of basic color lexicons. American Anthropologist, 101, 743-760.

Regier, T., Kay, P., & Cook, R. S. (2005). Focal colors are universal after all. Proceedings of the National Academy of Sciences USA, 102, 8386–8391.

Wright, O. (2012). Categorical influences on chromatic search asymmetries. Visual Cognition, 20, 947–987.

Zhou, K., Mo, L., Kay, P., Kwok, V. P. Y., Ip, T. N. M., & Tan, L. H. (2010). Newly trained lexical categories produce lateralized categorical perception of color. Proceedings of the National Academy of Sciences USA, 107, 9974–9978.

David Ludden is the author of The Psychology of Language: An Integrated Approach (SAGE Publications).