Shakespeare once wrote that which we call a rose, by any other name would smell as sweet. But does the fact that it's called a rose actually affect how people perceive the flower? That's a question that has been puzzling scientists since the 1930s, when Benjamin Lee Whorf proposed his linguistic theory that language can influence the nature and content of thought. Findings published online today by the journal Science support the Whorfian hypothesis and indicate that the language of numbers shapes how members of a small South American tribe count.

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.