Sign Language Sign language, used by hearing-impaired people, meets all the formal requirements for language, including syntax, displacement, and generativity. The similarities between spoken language and sign language have been confirmed by brain-imaging studies. The same brain regions are activated in hearing people when they speak as in deaf people when they use sign language (Hickok & others, 2001; Lubbadeh, 2005).

AP Photo/Al Behrman