Sign language

A sign language (also signed language) is a language which uses manual communication instead of sound to convey meaning - simultaneously combining handshapes, orientation and movement of the hands, arms or body, and facial expressions to fluidly express a speaker's thoughts. Sign languages develop in deaf communities, which can include interpreters and friends and families of deaf people as well as people who are deaf or hearing-impaired themselves.

When people using different signed languages meet communication is significantly easier than when people of different spoken languages meet. Sign language in this respect gives access to an international deaf community.

However, contrary to popular belief, sign language is not universal. Wherever communities of deaf people exist, sign languages develop, but as with spoken languages, these vary from region to region. They are not based on the spoken language in the country of origin; in fact their complex spatial grammars are markedly different. However, various signed "modes" of spoken languages have been developed, such as Signed English and Walpiri Sign Language. Hundreds of sign languages are in use around the world and are at the core of local Deaf cultures. Some sign languages have obtained some form of legal recognition, while others have no status at all.

Geographic distribution of Sign languages
In principle, and without too much error, one could state that each spoken language has a sign language counterpart in as much as each linguistic population will contain deaf members who will generate a sign language. In much the same way that geographical or cultural forces will isolate populations and lead to the generation of different and distinct spoken languages, the same forces operate on sign languages and so they tend to maintain their identities through time in roughly the same areas of influence as the local spoken tongues. This occurs even though sign languages have no relation to the spoken languages of the lands in which they arise. There are notable exceptions to this pattern, however, as some geographic regions sharing a spoken language have multiple, unrelated signed languages.

Variations within a 'national' sign language can usually be correlated to the geographic location of (residential) schools for the deaf.

An invented "international sign language" Gestuno is used for international Deaf events such as the Deaflympics and World Federation of the Deaf. It is analogous to its spoken language counterpart, Esperanto, which is also an invented language designed to be easy-to-learn and neutral.

Use of Signs in Hearing Communities
Gesture is a typical component of spoken languages. More elaborate systems of manual communication have developed in situations where speech is not practical or permitted, such as cloistered religious communities, scuba diving, television recording studios, loud workplaces, while hunting (see Kalahari bushmen) or in the game Charades. Recently, there has been a movement to teach and encourage the use of sign language with toddlers before they learn to talk and with non-hearing-impaired children with other causes of speech impairment or delay. This is typically referred to as Baby Sign.

On occasion, where the prevalence of deaf people is high enough, a deaf sign language has been taken up by an entire local community. Famous examples of this include Martha's Vineyard Sign Language in the USA, Kata Kolok in a village in Bali, Adamorobe Sign Language in Ghana and Yucatec Maya sign language in Mexico. In such communities deaf people are not socially disadvantaged.

Many Australian Aboriginal sign languages arose in a context of extensive speech taboos, such as during mourning and initiation rites. They are or were especially highly developed among the Warlpiri, Warumungu, Dieri, Kaytetye, Arrernte, Warlmanpa. However, these are manually coded versions of the spoken languages, and are not used by the deaf.

A pidgin sign language arose among tribes of American Indians in the Great Plains region of North America (see Plains Indians). It was used to communicate among tribes with different spoken languages. There are especially users today among the Crow, Cheyenne, and Arapaho. Unlike other sign languages developed by hearing people, it shares the spatial grammar of deaf sign languages.

Linguistics of sign
In linguistic terms, sign languages are as rich and complex as any oral language, despite the common misconception that they are not "real languages". Professional linguists have studied many sign languages and found them to have every linguistic component required to be classed as true languages.

Sign languages are not pantomime, and they are not a visual rendition of an oral language. They have rich, complex grammars of their own, and can be used to discuss any topic, from the simple and concrete to the lofty and abstract.

Sign languages, like oral languages, organize elementary, meaningless units (phonemes; once called cheremes in the case of sign languages) into meaningful semantic units. The elements of a sign are Handshape (or Handform), Orientation (or Palm Orientation), Location (or Place of Articulation), Movement, and Non-manual markers (or Facial Expression), summarised in the acronym HOLME.

Common linguistic features of deaf sign languages are extensive use of classifiers, a high degree of inflection, and a topic-comment syntax. Many unique linguistic features emerge from sign languages' ability to produce meaning in different parts of the visual field simultaneously. For example, the recipient of a signed message can read meanings carried by the hands, the facial expression and the body posture in the same moment. This is in contrast to oral languages, where the sounds that comprise words are mostly sequential (tone being an exception).

Sign languages' relationships with oral languages
A common misconception is that sign languages are somehow dependent on oral languages, that is, that they are oral language spelled out in gesture, or that they were invented by hearing people. Hearing teachers of deaf schools, such as Thomas Hopkins Gallaudet, are often incorrectly referred to as inventors of sign language.

Fingerspelling is used in sign languages, mostly for proper names. The use of fingerspelling was once taken as evidence that sign languages are simplified versions of oral languages, but in fact it is merely one tool among many. Fingerspelling can sometimes be a source of new signs, which are called lexicalized signs.

On the whole, deaf sign languages are independent of oral languages and follow their own paths of development. For example, British Sign Language and American Sign Language are quite different and mutually unintelligible, even though the hearing people of Britain and America share the same oral language.

Similarly, countries which use a single oral language throughout may have two or more sign languages; whereas an area that contains more than one oral language might use only one sign language.

Spatial grammar and Simultaneity
Sign languages exploit the unique features of the visual medium. Oral language is linear. Only one sound can be made or received at a time. Sign language, on the other hand, is visual; hence a whole scene can be taken in at once. Information can be loaded into several channels and expressed simultaneously. As an illustration, in English one could utter the phrase, "I drove here". To add information about the drive, one would have to make a longer phrase or even add a second, such as, "I drove here along a winding road," or "I drove here. It was a nice drive." However, in American Sign Language, information about the shape of the road or the pleasing nature of the drive can be conveyed simultaneously with the verb 'drive' by inflecting the motion of the hand, or by taking advantage of non-manual signals such as body posture and facial expression, at the same time that the verb 'drive' is being signed. Therefore, whereas in English the phrase "I drove here and it was very pleasant" is longer than "I drove here", in American Sign Language the two may be the same length.

Written forms of Sign Languages
Sign language differs from oral language in its relation to writing. The phonemic systems of oral languages are primarily sequential: that is, the majority of phonemes are produced in a sequence one after another, although many languages also have non-sequential aspects such as tone. As a consequence, traditional phonemic writing systems are also sequential, with at best diacritics for non-sequential aspects such as stress and tone.

Sign languages have a higher non-sequential component, with many phonemes produced simultaneously. For example, signs may involve fingers, hands, and face moving simultaneously, or the two hands moving in different directions. Traditional writing systems are not designed to deal with this level of complexity.

Partially because of this, sign languages are not often written. Most deaf signers read and write the oral language of their country. However, there have been several attempts at developing scripts for sign language. These have included both phonetic systems, such as HamNoSys (the Hamburg Notational System) and SignWriting, which can be used for any sign language, and phonemic systems such as the one used by William Stokoe in his 1965 Dictionary of American Sign Language, which are designed for a specific language. The only one of these writing systems that has been actually used by deaf people to write is SignWriting, which was devised by a dancer rather than a linguist.

These systems are based on iconic symbols. Some, such as SignWriting and HamNoSys, are pictographic, being conventionalized pictures of the hands, face, and body; others, such as the Stokoe notation, are more iconic. Stokoe used letters of the Latin alphabet and Hindu numerals to indicate the handshapes used in fingerspelling, such as 'A' for a closed fist, 'B' for a flat hand, and '5' for a spread hand; but non-alphabetic symbols for location and movement, such as '[]' for the trunk of the body, '×' for contact, and '^' for an upward movement. Lloyd Anderson has gone further and attempted to write ASL using only the Latin alphabet, but has not published his work.

SignWriting, being pictographic, is able to represent simultaneous elements in a single sign. The Stokoe notation, on the other hand, is sequential, with a conventionalized order of a symbol for the location of the sign, then one for the hand shape, and finally one (or more) for the movement. The orientation of the hand is indicated with an optional diacritic before the hand shape. When two movements occur simultaneously, they are written one atop the other; when sequential, they are written one after the other. Neither the Stokoe nor HamNoSys scripts are designed to represent facial expressions or non-manual movements, both of which SignWriting accommodates easily, although this is being gradually corrected in HamNoSys.

Home sign

 * See main article: Home sign

Sign systems are sometimes developed within a single family. For instance, when hearing parents with no sign language skills have a deaf child, an informal system of signs will naturally develop, unless repressed by the parents. The term for these mini-languages is home sign (sometimes homesign or kitchen sign).

Home sign arises due to the absence of any other way to communicate. Within the span of a single lifetime and without the support or feedback of a community, the child is forced to invent signals to facilitate the meeting of his or her communication needs. Although this kind of system is grossly inadequate for the intellectual development of a child and it comes nowhere near meeting the standards linguists use to describe a complete language, it is a common occurrence.