Black American sign language and American sign language are different languages:
Some differences result from a familiar history of privation in black education. Schools for black deaf children — the first of them opened some 50 years after the Hartford school was founded, and most resisted integration until well after the Brown v. Board of Education decision of 1954— tended to have fewer resources. Students were encouraged to focus on vocational careers — repairing shoes or working in laundries — rather than pursuing academic subjects, Lucas says, and some teachers had poor signing skills.But a late-19th-century development in the theory of how to teach deaf children led, ironically, to black students’ having a more consistent education in signing. The so-called oralism movement, based on the now controversial notion that spoken language is inherently superior to sign language, placed emphasis on teaching deaf children how to lip-read and speak.
The cultural differences in sign language extend to other English speakers too. As the article points out, “[American Sign Language] is about 60 percent the same as French, and unintelligible to users of British sign language.”