The mili and mola worldview
In the Baliem Valley of Indonesia's Papua region, the Dani people have traditionally described their world with two basic color terms. Their language classifies all cool and dark shades—such as blue, green, and black—as mili. All warm and light colors—like red, yellow, and white—are called mola. This linguistic structure posed a fascinating question for cognitive scientists: does the language you speak determine what you can see?
This question is important to the theory of linguistic relativity, also known as the Sapir-Whorf hypothesis. The strong version of this idea, linguistic determinism, suggests that language dictates the categories of our thought and perception. If this were true, a Dani speaker might not be able to readily distinguish between a blue and a green object, since both fall under the single category of mili. In the early 1970s, psychologist Eleanor Rosch (then Heider) traveled to the Baliem Valley to test this idea.
A test of perception
Rosch designed a series of ingenious experiments to see if the Dani's two-color language constrained their actual color perception. The studies did not investigate whether the Dani could physically see the same spectrum of light, but whether they could cognitively organize and remember colors they did not have names for.
One important experiment tested short-term memory. Rosch showed Dani participants a single color chip for five seconds. After a brief pause, she presented them with a large array of color chips and asked them to identify the one they had just seen. Some of the chips were "focal" colors—what English speakers would consider a pure, ideal example of a color like red or blue. Others were non-focal, in-between shades. The Dani, just like an American control group, remembered the focal colors far more accurately than the non-focal ones.
Another experiment tested learning. Rosch taught Dani volunteers new, made-up names for eight focal and eight non-focal colors. The participants learned the names for the perceptually distinct focal colors much more quickly and with fewer errors than the names for non-focal colors. The structure of their mili and mola system did not prevent acquiring a more complex, multi-hued vocabulary.
The results challenged the idea of linguistic determinism. The Dani could clearly see, remember, and learn about colors for which they had no words. Rosch's work showed that color perception has a universal component, likely tied to the physiology of the human visual system, that exists independently of language. While language can influence thought, it does not prevent around what we can perceive.