John Carter, the big-budget Disney movie that opened last Friday, has been billed as "Indiana Jones on Mars." But the film boasts more than a rakish hero battling giant green aliens. It also features an invented language, Thark, devised by Paul Frommer, a linguist at the University of Southern California. Such fabricated tongues have become a standard accoutrement of Hollywood movies set in fantastical places: Frommer also created Na’vi, the language spoken by the inhabitants of Pandora in the 2009 smash Avatar. What devotees of Na’vi—and the Klingon of Star Trek and the Elvish of Lord of the Rings—may not realize is that linguists and other social scientists employ invented words to explore how we use language here on planet Earth.
Perhaps the most famous experiment involving invented words was conducted in the late 1950s by Jean Berko, then a graduate student in linguistics at Harvard. Berko showed children a drawing of a cute creature, telling them, “This is a wug.” Then she showed them a picture of a second creature just like the first, commenting: “Now there are two of them. There are two…?” Very young children, Berko reported, would look baffled, or reply “Two wug.” But kids aged four and five would usually respond, “Two wugs!” These children had mastered the principle stipulating that a noun in English is (usually) made plural by adding an “s” on the end, and they had applied the principle to a word they had never encountered before—evidence that even preschoolers could extract general rules about language from the speech they heard around them.
The virtue of invented words as they’re used in the laboratory is that they eliminate the possibility that the terms will be familiar to some participants and not to others. Creating new languages also allows scientists to tailor the words to the needs of their studies. When researchers at Northwestern University were investigating how bilingual individuals learn additional languages, for example, they needed to observe them learning a language that was completely different from the tongues they already spoke. To do so, they came up with words unlike any found in English, Spanish, or Mandarin Chinese, the languages spoken by the study’s participants. Although the made-up words incorporated sounds that were absent from the languages they already knew, the bilingual subjects still managed to learn twice as many of the words as subjects who spoke only English—evidence, the researchers concluded, that bilingualism confers an advantage in vocabulary learning.
Researchers have even used invented language to investigate whether the words we use shape the way we think. In 1955, a sociologist named James Cooke Brown set out to create a language that made logic the guiding principle of its design. “Brown wanted to test the idea that speaking in logic would make people more logical,” explains linguist Arika Okrent, author of the book In the Land of Invented Languages. It didn’t work out quite that way. Although Brown devoted several decades to developing the language, called Loglan, he never carried out any studies of its effects on thinking, and it never caught on beyond a small circle of devotees. But perhaps that’s only fitting: Brown was also a writer of science fiction. If he were still around today (Brown died in 2000), he would probably be fluent in Thark.
This article originally appeared in Time.com