Peter Gordon of Columbia University spent years studying an isolated Amazon tribe called the Pirahã that has fewer than 200 members. Pirahã people use a counting system in which quantities beyond two are not differentiated but are instead referred to simply as many. In addition, the word for one can actually mean approximately one. To test whether this systems limits how the Pirahã perceive larger amounts, Gordon gave tribe members numerical tasks in which they were asked to match small groups of items based on how many objects were present. Although the adults performed well when there were one, two or three items, their accuracy declined when there were eight to 10 things. With larger groups, they always answered incorrectly.
The results indicate that language can define cognition, at least when it comes to numbers. Whether one language chooses to distinguish one thing versus another affects how an individual perceives reality, Gordon says. But he cautions that the situation may be unique, and that the linguistic determinism theory may not hold for all types of thought.