asl idioms alexander graham bell alice cogswell american school for the deaf american sign language grammar anglophone benin british sign language burkina faso canada central african republic chad child development democratic republic of the congo dominican republic el salvador filipino sign language fingerspelling founder effect french sign language gabon gallaudet university ghana grammar haiti harvard university press home sign hong kong indigenous peoples of the americas initial interlanguage italy kenya language family laurent clerc legal recognition of sign languages lexicon list of sign languages madagascar malaysia manualism massachusetts mauritania mexico natural language nigeria north america old french sign language paris philippines phoneme phonology plains indian sign language pragmatics puerto rico registry of interpreters for the deaf semantics signwriting sign language signing exact english singapore spoken language stokoe notation syntax texas thomas hopkins gallaudet togo united states wikibooks wiktionary william stokoe zimbabwe