Nonvocal communication systems employing primarily the manual and brachial and, to some extent, facial musculature may coexist with a vocal language, or may develop in its absence. In the former case they are usually adjunct and fairly elementary systems, such as are employed by some hunting groups when they wish to communicate in silence, or by North American Indians in the past to communicate across tribes. The more elaborate development of manual systems of communication is found almost exclusively among the deaf, in whom it has flourished in practically every culture, despite past suppression by the hearing educators of the deaf. The readiness with which idiosyncratic manual communication systems develop when even a small number of deaf persons reside near each other indicates that a manual system is a very natural and readily available means of communication to human beings.
- Gardner RA, Gardner BT (1978): Comparative psychology and language acquisition. In: Psychology, the State of the Art, Salzinger K, Denmark FL, eds. Ann NY Acad Sci 309.Google Scholar
- Poizner H, Bellugi U, Iragui V (1984): Apraxia and aphasia for a visual-gestural language. Am J Physiol 15:R868–R883.Google Scholar
- Stokoe WC, Casterline DC, Cronebcrg GG (1976): A Dictionary of American Sign Language on Linguistic Principles, new ed. Silver Spring, Md: Linstok PressGoogle Scholar