The online journal American Scientist says: “Toddlers manage to acquire language even when their parents don’t talk to them directly; deaf children will go so far as to invent their own sign languages if they are not exposed to sign at home. ”
تا جایی که اگر به کودکان ناشنوا زبان اشاره‌ای آموخته نشود زبان اشاره‌ای مختص به خود اختراع می‌کنند .‏ »‏