According to New Scientist, an experiment in Brazil may offer evidence for linguistic determinism—"the controversial hypothesis that the language available to humans defines our thoughts."
Hunter-gatherers from the Pirahã tribe, whose language only contains words for the numbers one and two, were unable to reliably tell the difference between four objects placed in a row and five in the same configuration, revealed the study….
In order to test if this prevented members of the tribe from perceiving higher numbers, Gordon set seven Pirahã a variety of tasks. In the simplest, he sat opposite an individual and laid out a random number of familiar objects, including batteries, sticks and nuts, in a row. The Pirahã were supposed to respond by laying out the same number of objects from their own pile.
For one, two and three objects, members of the tribe consistently matched Gordon's pile correctly. But for four and five and up to ten, they could only match it approximately, deviating more from the correct number as the row got longer….
Gordon says this is the first convincing evidence that a language lacking words for certain concepts could actually prevent speakers of the language from understanding those concepts.
The article acknowledges that there could be other reasons for the Indians' poor results, "including not being used to dealing with large numbers." There is also the possibility, left unexplored, that tribal people simply enjoy screwing with researchers' heads.