While Pinker and others say that logically there must be a universal grammar, finding proof of such a structure is a different matter. Much as physicists will never actually see gravity but still study the force's effects on other objects, linguists must use an indirect approach in their research. These cognitive scientists look for places where the instinct of language still shows, places untouched by the more complicated language of the everyday world. They compare languages, looking for universal rules. They study children learning languages.
Linguists compare languages, looking for universal rules.
Others translate one language to another, allowing the various components of our species to understand each other and work together. In an NSF-funded project, the psychologist from the University of Chicago studied ten deaf children in Chicago and Philadelphia. The children were born to hearing parents and, due to the parent's convictions of the importance of oral language, did not learn sign language. But after many hours of watching video taped sessions, Goldin-Meadow concludes that they used a more sophisticated system. The children, ages 14 months to four years, developed internally consistent sign languages.