Recently, I learned that signed languages don't necessarily have anything to do with the language spoken by the hearing people who live in the same country. American Sign Language isn't just English done with your hands. In fact, it's a completely different language from British Sign Language—a deaf American and a deaf Briton wouldn't be able to converse any better than an English speaker could with someone who speaks Japanese.
Sign languages tend to spontaneously emerge when the deaf people of a country or region first start coming together to form a community, usually based around a school. It's happening right now in Nicaragua, where special education schools opened in the 1970s. Over the past 30 years, Nicaraguan Sign Language has evolved from simple gestures between friends, to a full and complete language. That recent evolution makes Nicaraguan Sign Language the enticing blue bug zapper to linguists' and cognitive scientists' curious moths. Case in point: The study of the way language and learning interact. The structure and composition of the language you speak has a big impact on how you think and perceive the world.
In the first version [of Nicaraguan Sign Language] developed in the 1970s, the children hadn't settled on a consistent way of indicating left and right, and the locations of objects in their conversations are fairly ambiguous. The second group of children to expand NSL in the 1980s had more specific conventions for position.
Pyers compared the abilities of people from both groups, now fully grown adults, in two spatial tests. First, she led them into a small room with a single red wall. She hid a token in one corner of the room, blindfolded the children and spun them around until they lost their bearings. When she removed the blindfold, the children had to say where the token was. The second test, like the first, involved hiding a token in the corner of a room, but this time the room was a tabletop model that was rotated while the children were blindfolded.
In both tests, the second group of adults (who learned the more advanced form of NSL) outperformed the first group. Even though their memories and ability to understand the tasks were just as good, the expanded vocabulary of geographical gestures that they learned as children also gave them better spatial abilities well into adulthood.
Not Exactly Rocket Science: New Nicaraguan Sign Language Shows How Language Affects Thought