Signed and spoken language

What is "sign language"?

Signed languages are visual-spatial languages used as the primary means of communication by communities of deaf people in various parts of the world. The version used in the U.S. and in anglophone Canada is called ASL (American Sign Language).

ASL is completely different from British Sign Language, for historical reasons: ASL developed out of a system brought to the U.S. in the 19th century by a French teacher of the deaf. As a result, ASL has more lexical affinities with the sign language spoken in France (and francophone Canada) than it does with the sign language of Britain.

 The Ethnologue index lists 103 Deaf Sign Languages

As an illustration of lexical diversity, here is the word for "university" in French, Italian and American sign languages:

Sign languages also differ in their syntax and morphology.

American Sign Language (ASL) vs. signed English.

There are various systems for producing a more-or-less exact signed version of a spoken language like English. None of these are  much like true sign language, except that they may share vocabulary, and none of them are in very widespread use. Pidgin Signed English is said to be "what happens when (English-speaking) adults try to learn ASL." PSE has variable influences from English syntax, and lacks many of the grammatical and morphological features of ASL, as well as many of the grammatical and morphological features of English. However, children exposed to PSE are said to acquire ASL, or something very much like it.
ASL and other sign languages have only been studied carefully by linguists for about 30 years. In the beginning, one of the key issues was to overcome "oralist" prejudices against sign, and to demonstrate its status as a "real" language, as opposed to a form of mime or charades. As a result, much of the work focused on issues of phonology-like aspects of ASL (such as its usage of a fixed repertory of hand shapes and motion types), and on fairly direct ASL analogues to morphology and syntax. More recently, linguists have begun to explore some of the fascinating ways in which the visual-spatial medium of sign is used to express linguistic structure in ways not available in the auditory-acoustic medium of speech.

Here is a paper that explains how head tilt and eye gaze are used to mark various agreement-like phenomena in ASL. Along the way, this paper indicates some of the ways in which true ASL syntax differs from English. For instance, if the WH-word in an ASL question is displaced, it must be to the end of the clause rather than to the beginning: "John see yesterday who?"

To read the paper, you'll have to download an Adobe Acrobat viewer, if your browser does not already have a "plug-in" for it. If you also download (or already have installed) a QuickTime viewer, you'll be able to see the paper's embedded movies. This is worth the trouble, because it will give you a better idea of what ASL is like.

The development of sign language

For a hundred years or more, there has been a debate about deaf education between "oralists" and "manualists." As recently as 20 years ago, there were many oralist schools for the deaf where signing was prohibited (on the grounds that it lessened the motivation for deaf children to learn to speak and to lip-read). Nevertheless, children in these schools would communicate privately in signed languages, which often were largely invented by the children at each school. Today, the debate in the U.S. has swung so far back in the other direction that deaf activists or other medical intervention, arguing that the culture of the deaf community has progressed to the point where attempts to cure or even ameliorate the condition of deafness are a kind of cultural genocide. This lengthy New York Times article on the subject is well worth the time to read.

Like any other language, a sign language requires a language community to develop or to be maintained. In many traditional societies, where deaf people live out their lives in the small communities in which they are born, there is not the "critical mass" of signers needed to create a true sign language. Instead, each deaf person develops an ad hoc sort of pidgin sign language to use with his or her relatives and neighbors.

In Nicaragua, this was the situation in place until about fifteen years ago, when a residential school for the deaf was established in Managua. Within a few years of the establishment of this school, a full-fledged Nicaraguan sign language came into existence.

The experiment of Psammetichus

The spontaneous emergence of sign languages is reminiscent of the fabled experiments of cruel rulers:

From the History of Herodotus, Book II:

From the Chronicle of Salimbene, thirteenth-century Italian Franciscan, writing about Frederick II of Hohenstaufen: The spontaneous emergence of sign languages in communities of deaf children shows how robust the human instinct for language is, and how strongly it will fight to emerge even under difficult circumstances. Of course it is foolish as well as cruel to suppose that children deprived of linguistic contact would develop some "original" or "natural" language. All languages, whether ancient or modern, are partly arbitrary systems developed within a particular speech community.

In addition, early linguistic experience is essential for the development of linguistic -- and to some extent cognitive -- competence at all. Thus the results attributed to Frederick II are much more plausible than those attributed to Psammetichus. During the key period of language (and cognitive) development, between the ages of one and three or so, profoundly deaf children simply cannot learn any language other than sign. Even at much later stages, oral education is slow and painful at best, and does not give profoundly deaf children an adequate basis for either linguistic or general cognitive development. This has been one of the key arguments of the "manualist" position in deaf education, though with the development of cochlear implants, the force of the argument has shifted somewhat.

Aphasia in signers

Since the modality of input and output is so different in signed and spoken forms of language, it is especially interesting that the correlations of neural damage location and aphasic symptoms in speaking and signing patients seem to be essentially the same. Deaf-from-birth signers suffer from sign-language versions of Broca's and Wernicke's aphasia, as well as other sorts of aphasia, just as hearing people do.

Writing sign language

Attempts to devise writing systems for sign language have a long history, with modern efforts going back at least to the work of William Stokoe at Gallaudet in the 1960s. The goals of such systems include teaching, the compilation of sign dictionaries, and especially the provision of a detailed "phonetic" transcription for research purposes. These days, it seems that video (including digital video) is reducing the pressures to develop sign writing systems for education and dictionary-making. However, there are several on-going efforts to develop IPA-like notations for research purposes, including the  Hamnosys  notation system from the University of Hamburg in Germany, and the American SignStream project. The SignWriting project aims at use as a writing system by ordinary signers as well as researchers.

Here is a short video of a German sign (for "tiring") with its Hamnosys notation.

Some other links

 Gallaudet University
 Information on Cochlear Implants
 Oral Deaf Education home page
 ASL Dictionary Online
 SL Dictionary on Psychological Terms (German)