Editing Sign language (section)

== Linguistics ==
Sign languages have capability and complexity equal to spoken languages; their study as part of the field of [[linguistics]] has demonstrated that they exhibit the fundamental properties that exist in all languages.<ref name=klima>[[Edward Klima|Klima, Edward S.]]; & [[Ursula Bellugi|Bellugi, Ursula]]. (1979). ''The signs of language''. Cambridge, MA: Harvard University Press. {{ISBN|0-674-80795-2}}.</ref><ref name="SLM">Sandler, Wendy; & Lillo-Martin, Diane. (2006). Sign Language and Linguistic Universals. Cambridge: Cambridge University Press.</ref><ref>{{cite book|last1=Baker|first1=Anne|last2=Bogaerde|first2=Beppie van den|last3=Pfau|first3=Roland|first4=G. M.|last4=Schermer|title=The Linguistics of Sign Languages: An Introduction|url=https://books.google.com/books?id=kC01jwEACAAJ|year=2016|publisher=John Benjamins Publishing Company|isbn=978-90-272-1230-6|page=2|access-date=2021-04-15|archive-date=2023-01-14|archive-url=https://web.archive.org/web/20230114125750/https://books.google.com/books?id=kC01jwEACAAJ|url-status=live}}</ref> Such fundamental properties include [[duality of patterning]]<ref>Stokoe, William C. 1960. [http://saveourdeafschools.org/stokoe_1960.pdf Sign Language Structure: An Outline of the Visual Communication Systems of the American Deaf] {{Webarchive|url=https://web.archive.org/web/20131202224634/http://saveourdeafschools.org/stokoe_1960.pdf |date=2013-12-02 }}, ''Studies in linguistics: Occasional papers (No. 8)''. Buffalo: Dept. of Anthropology and Linguistics, University of Buffalo.</ref> and [[Recursion#In language|recursion]].<ref>Bross, Fabian (2020). The clausal syntax of German Sign Language. A cartographic approach. Berlin: Language Science Press. Page 37-38.</ref> Duality of patterning means that languages are composed of smaller, meaningless units which can be combined into larger units with meaning (see below). The term recursion means that languages exhibit grammatical rules and the output of such a rule can be the input of the same rule. It is, for example, possible in sign languages to create [[subordinate clause]]s and a subordinate clause may contain another subordinate clause.

Sign languages are not [[mime]]—in other words, signs are conventional, often arbitrary and do not necessarily have a visual relationship to their referent, much as most spoken language is not [[onomatopoeic]]. While [[iconicity]] is more systematic and widespread in sign languages than in spoken ones, the difference is not categorical.<ref>[[Trevor Johnston|Johnston, Trevor]] A. (1989). [https://web.archive.org/web/20080726084538/http://homepage.mac.com/trevor.a.johnston/dissertation.htm  ''Auslan: The Sign Language of the Australian Deaf community'']. The University of Sydney: unpublished Ph.D. dissertation.</ref> The visual modality allows the human preference for close connections between form and meaning,  to be more fully expressive, where as this is more suppressed  in spoken language.,<ref name="Taub 2001"/>

Sign languages, like spoken languages, organize elementary, meaningless units into meaningful [[semantic]] units. This type of organization in natural language is often called [[duality of patterning]]. As in spoken languages, these meaningless units are represented as (combinations of) [[Feature (linguistics)|features]], although coarser descriptions are often also made in terms of five "parameters": [[handshape]] (or ''handform''), [[Orientation (sign language)|orientation]], [[Location (sign language)|location]] (or ''place of articulation''), [[Movement (sign language)|movement]], and non-manual [[Expression (sign language)|expression]]. These meaningless units in sign languages were initially called [[chereme]]s,<ref>Fabian Bross (2016). [https://www.researchgate.net/publication/317336147_Chereme_In_Hall_T_A_Pompino-Marschall_B_ed_Dictionaries_of_Linguistics_and_Communication_Science_Worterbucher_zur_Sprach-_und_Kommunikationswissenschaft_WSK_Volume_Phonetics_and_Phonology_Berlin_New_Y "Chereme"] {{webarchive |url=https://web.archive.org/web/20180317231914/https://www.researchgate.net/publication/317336147_Chereme_In_Hall_T_A_Pompino-Marschall_B_ed_Dictionaries_of_Linguistics_and_Communication_Science_Worterbucher_zur_Sprach-_und_Kommunikationswissenschaft_WSK_Volume_Phonetics_and_Phonology_Berlin_New_Y |date=2018-03-17 }}. In: Hall, T. A. Pompino-Marschall, B. (ed.): Dictionaries of Linguistics and Communication Science. Volume: Phonetics and Phonology. Berlin, New York: Mouton de Gruyter.</ref> from the Greek word for ''hand'', by analogy to the [[phoneme]]s, from Greek for ''voice'', of spoken languages. Now they are sometimes called phonemes when describing sign languages too, since the function is essentially the same, but more commonly discussed in terms of "features"<ref name="SLM" /> or "parameters".<ref>{{cite web |last1=Vicars |first1=Bill |title=American Sign Language: "parameters" |url=https://www.lifeprint.com/asl101/pages-layout/parameters.htm#:~:text=Note%20if%20you%20are%20taking,%2C%20movement%2C%20and%20palm%20orientation. |website=ASL University |publisher=Bill Vicars |access-date=2021-08-13 |archive-date=2021-11-29 |archive-url=https://web.archive.org/web/20211129115338/https://www.lifeprint.com/asl101/pages-layout/parameters.htm#:~:text=Note%20if%20you%20are%20taking,%2C%20movement%2C%20and%20palm%20orientation. |url-status=live }}</ref> More generally, both sign and spoken languages share the [[Hockett's design features|characteristics]] that linguists have found in all natural human languages, such as transitoriness, [[semanticity]], [[arbitrariness]], [[Productivity (linguistics)|productivity]], and [[Traditional transmission|cultural transmission]].{{Clarify|reason=further explanation of what is meant by these terms is needed|date=June 2019}}

Common linguistic features of many sign languages are the occurrence of [[Classifier constructions in sign languages|classifier constructions]], a high degree of [[inflection]] by means of changes of movement, and a [[Topic-comment language|topic-comment]] [[syntax]]. More than spoken languages, sign languages can convey meaning by simultaneous means, e.g. by the use of [[Signing space|space]], two manual articulators, and the signer's face and body. Though there is still much discussion on the topic of iconicity in sign languages, classifiers are generally considered to be highly iconic, as these complex constructions "function as predicates that may express any or all of the following: motion, position, stative-descriptive, or handling information".<ref>Emmorey, K. (2002). ''Language, cognition and the brain: Insights from sign language research''. Mahwah, NJ: Lawrence Erlbaum Associates.</ref> The term classifier is not used by everyone working on these constructions. Across the field of sign language linguistics the same constructions are also referred with other terms such as depictive signs.{{citation needed|date=October 2024}}

Today, linguists study sign languages as true languages, part of the field of linguistics. However, the category "sign languages" was not added to the [[Linguistic Bibliography|''Linguistic Bibliography/Bibliographie Linguistique'']] until the 1988 volume,<ref>{{cite book |pages=970–972 |title=Linguistic Bibliography for the Year 1988 |year=1990 |isbn=978-07-92-30936-9 |place=Leiden, Netherlands |publisher=Brill |editor1=Janse, Mark |editor2=Borkent, Hans |editor3=Tol, Sijmen}}</ref> when it appeared with 39 entries.

=== Relationships with spoken languages ===
[[Image:Holečkova, nápis ve znakové řeči.jpg|thumb| Sign language relief sculpture on a stone wall: "Life is beautiful, be happy and love each other", by Czech sculptor [[Zuzana Čížková]] on Holečkova Street in [[Prague]]-[[Smíchov]], by a school for the deaf]]

There is a common misconception<ref>{{Cite journal |last1=Pirot |first1=Khunaw Sulaiman |last2=Ali |first2=Wrya Izaddin |date=2021-09-29 |title=The Common Misconceptions about Sign Language |url=http://journal.uor.edu.krd/index.php/JUR/article/view/629 |journal=Journal of University of Raparin |volume=8 |issue=3 |pages=110–132 |doi=10.26750/Vol(8).No(3).Paper6 |s2cid=244246983 |issn=2522-7130 |doi-access=free |access-date=2022-09-26 |archive-date=2022-12-04 |archive-url=https://web.archive.org/web/20221204075309/http://journal.uor.edu.krd/index.php/JUR/article/view/629 |url-status=live }}</ref> that sign languages are [[manually coded language|spoken language expressed in signs]], or that they were invented by hearing people.<ref>{{cite web|last=Perlmutter|first=David M.|title=What is Sign Language?|url=http://www.linguisticsociety.org/files/Sign_Language.pdf|work=LSA|access-date=4 November 2013|url-status=live|archive-url=https://web.archive.org/web/20140412004710/http://www.linguisticsociety.org/files/Sign_Language.pdf|archive-date=12 April 2014}}</ref> Similarities in [[Sign language in the brain|language processing in the brain]] between signed and spoken languages further perpetuated this misconception. Hearing teachers in deaf schools, such as Charles-Michel de l'Épée or Thomas Hopkins Gallaudet, are often incorrectly referred to as "inventors" of sign language. Instead, sign languages, like all natural languages, are developed by the people who use them, in this case, deaf people, who may have little or no knowledge of any spoken language.

As a sign language develops, it sometimes borrows elements from spoken languages, just as all languages borrow from other languages that they are in contact with. Sign languages vary in how much they borrow from spoken languages. In many sign languages, a manual alphabet ("fingerspelling") may be used in signed communication to borrow a word from a spoken language. This is most commonly used for proper names of people and places; it is also used in some languages for concepts for which no sign is available at that moment, particularly if the people involved are to some extent bilingual in the spoken language. Fingerspelling can sometimes be a source of new signs, such as initialized signs, in which the handshape represents the first letter of a spoken word with the same meaning.
[[File:Keep Wales Safe This Winter- British Sign Language (BSL).webm|thumb|A January 2021 [[Welsh Government]] video informing viewers of their new [[COVID-19 pandemic in Wales|COVID-19]] regulations]]

On the whole, though, sign languages are independent of spoken languages and follow their own paths of development. For example, [[British Sign Language]] (BSL) and [[American Sign Language]] (ASL) are quite different and mutually unintelligible, even though the hearing people of the United Kingdom and the United States share the same spoken language. The grammars of sign languages do not usually resemble those of spoken languages used in the same geographical area; in fact, in terms of syntax, ASL shares more with spoken [[Japanese grammar|Japanese]] than it does with English.<ref>[[Karen Nakamura|Nakamura, Karen]]. (1995). "About American Sign Language." Deaf Resource Library, Yale University. [http://www.deaflibrary.org/asl.html] {{Webarchive|url=https://web.archive.org/web/20130519230633/http://www.deaflibrary.org/asl.html|date=2013-05-19}}</ref>

Similarly, countries which use a single spoken language throughout may have two or more sign languages, or an area that contains more than one spoken language might use only one sign language. [[South Africa]], which has 11 official spoken languages and a similar number of other widely used spoken languages, is a good example of this. It has only one sign language with two variants due to its history of having two major educational institutions for the deaf which have served different geographic areas of the country.

=== Spatial grammar and simultaneity ===
[[File:Hello1.ogv|thumb|''Hello'' in ASL (American Sign Language)]]
[[File:Hello2.ogv|thumb|Another variation of ''hello'' in ASL (American Sign Language)]]
Sign languages exploit the unique features of the visual medium (sight), but may also exploit tactile features ([[Tactile signing|tactile sign languages]]). Spoken language is by and large linear; only one sound can be made or received at a time. Sign language, on the other hand, is visual and, hence, can use a simultaneous expression, although this is limited articulatorily and linguistically. Visual perception allows processing of simultaneous information.

One way in which many sign languages take advantage of the spatial nature of the language is through the use of classifiers. [[Classifier constructions in sign languages|Classifiers]] allow a signer to spatially show a referent's type, size, shape, movement, or extent.

The possible simultaneity of sign languages in contrast to spoken languages is sometimes exaggerated. The use of two manual articulators is subject to motor constraints, resulting in a large extent of symmetry<ref>Battison, Robbin (1978). ''Lexical Borrowing in American Sign Language.'' Silver Spring, MD: Linstok Press.</ref> or signing with one articulator only. Further, sign languages, just like spoken languages, depend on linear sequencing of signs to form sentences; the greater use of simultaneity is mostly seen in the [[Morphology (linguistics)|morphology]] (internal structure of individual signs).

=== Non-manual elements ===
{{main|Nonmanual feature}}
Sign languages convey much of their [[prosody (linguistics)|prosody]] through non-manual elements. Postures or movements of the body, head, eyebrows, eyes, cheeks, and mouth are used in various combinations to show several categories of information, including [[lexical item|lexical]] distinction, [[grammar|grammatical]] structure, [[adjective|adjectival]] or [[adverb]]ial content, and [[discourse]] functions.

At the lexical level, signs can be lexically specified for non-manual elements in addition to the manual articulation. For instance, facial expressions may accompany verbs of emotion, as in the sign for ''angry'' in [[Czech Sign Language]]. Non-manual elements may also be lexically contrastive. For example, in ASL (American Sign Language), facial components distinguish some signs from other signs. An example is the sign translated as ''not yet'', which requires that the tongue touch the lower lip and that the head rotate from side to side, in addition to the manual part of the sign. Without these features the sign would be interpreted as ''late''.<ref>Liddell, Scott K. (2003). ''Grammar, Gesture, and Meaning in American Sign Language.'' Cambridge: Cambridge University Press.</ref> [[Mouthing]]s, which are (parts of) spoken words accompanying lexical signs, can also be contrastive, as in the manually identical signs for ''doctor'' and ''battery'' in [[Dutch Sign Language|Sign Language of the Netherlands]].<ref>{{Cite book |title=SignGram blueprint: A guide to sign language grammar writing |publisher=De Gruyter Mouton |editor1=Josep Quer i Carbonell |editor2=Carlo Cecchetto |editor3=Rannveig Sverrisd Ãttir |year=2017 |isbn=9781501511806 |oclc=1012688117}}</ref>

While the content of a signed sentence is produced manually, many grammatical functions are produced non-manually (i.e., with the face and the torso).<ref>{{cite journal | last1 = Bross | first1 = Fabian | last2 = Hole | first2 = Daniel | title = Scope-taking strategies in German Sign Language | journal = Glossa | volume = 2 | issue = 1| pages = 1–30 | doi = 10.5334/gjgl.106 | doi-access = free }}</ref> Such functions include questions, negation, relative clauses and topicalization.<ref>{{cite journal|last=Boudreault|first=Patrick|author2=Mayberry, Rachel I.|year=2006|title=Grammatical processing in American Sign Language: Age of first-language acquisition effects in relation to syntactic structure|journal=Language and Cognitive Processes|volume=21|issue=5|pages=608–635|doi=10.1080/01690960500139363|s2cid=13572435}}</ref> ASL and BSL use similar non-manual marking for yes/no questions, for example. They are shown through raised eyebrows and a forward head tilt.<ref name="Baker&Cokely">Baker, Charlotte, and Dennis Cokely (1980). ''American Sign Language: A teacher's resource text on grammar and culture.'' Silver Spring, MD: T.J. Publishers.</ref><ref name="Sutton-Spence&Woll">Sutton-Spence, Rachel, and Bencie Woll (1998). ''The linguistics of British Sign Language.'' Cambridge: Cambridge University Press.</ref>

Some adjectival and adverbial information is conveyed through non-manual elements, but what these elements are varies from language to language. For instance, in ASL a slightly open mouth with the tongue relaxed and visible in the corner of the mouth means "carelessly", but a similar non-manual in BSL means "boring" or "unpleasant".<ref name=Sutton-Spence&Woll />

Discourse functions such as [[conversation analysis|turn taking]] are largely regulated through head movement and eye gaze. Since the addressee in a signed conversation must be watching the signer, a signer can avoid letting the other person have a turn by not looking at them, or can indicate that the other person may have a turn by making eye contact.<ref>Baker, Charlotte (1977). Regulators and turn-taking in American Sign Language discourse, in Lynn Friedman, ''On the other hand: New perspectives on American Sign Language.'' New York: Academic Press. {{ISBN|9780122678509}}</ref>

=== Iconicity ===
[[Iconicity]] is similarity or analogy between the form of a sign (linguistic or otherwise) and its meaning, as opposed to [[Arbitrariness#Linguistics|arbitrariness]].<ref>{{cite journal |last1=Bross|first1=F. |year=2024 |title=What is iconicity? |journal=Sign Language & Linguistics |volume=27 |issue=1 |pages=73–102 |doi=10.1075/sll.22003.bro |url=https://lingbuzz.net/lingbuzz/008405|url-access=subscription }}</ref> The first studies on iconicity in ASL were published in the late 1970s and early 1980s.  Many early sign language linguists rejected the notion that iconicity was an important aspect of sign languages, considering most perceived iconicity to be extralinguistic.<ref name=":2"/><ref name=klima/> However, mimetic aspects of sign language (signs that imitate, mimic, or represent) are found in abundance across a wide variety of sign languages. For example, when deaf children learning sign language try to express something but do not know the associated sign, they will often invent an iconic sign that displays mimetic properties.<ref>{{cite journal|author1=Klima, Edward|author2= Bellugi, Ursula|title=The Signs of Language|journal= Sign Language Studies|volume= 1062|issue=1|year= 1989|pages=  11}}</ref> Though it never disappears from a particular sign language, iconicity is gradually weakened as forms of sign languages become more customary and are subsequently grammaticized. As a form becomes more conventional, it becomes disseminated in a methodical way phonologically to the rest of the sign language community.<ref>Brentari, Diane. "Introduction." Sign Languages, 2011, pp. 12.</ref> Nancy Frishberg concluded that though originally present in many signs, iconicity is degraded over time through the application of natural grammatical processes.<ref name=":2" />

In 1978, psychologist [[Roger Brown (psychologist)|Roger Brown]] was one of the first to suggest that the properties of ASL give it a clear advantage in terms of learning and memory.<ref>{{cite journal | last1 = Brown | first1 = R | year = 1978 | title = Why Are Signed Languages Easier to Learn than Spoken Languages? Part Two | journal = Bulletin of the American Academy of Arts and Sciences | volume = 32 | issue = 3| pages = 25–44 | doi = 10.2307/3823113 | jstor = 3823113 }}</ref>  In his study, Brown found that when a group of six hearing children were taught signs that had high levels of iconic mapping they were significantly more likely to recall the signs in a later memory task than another group of six children that were taught signs that had little or no iconic properties. In contrast to Brown, linguists [[Elissa L. Newport|Elissa Newport]] and Richard Meier found that iconicity "appears to have virtually no impact on the acquisition of American Sign Language".<ref>{{Cite book|title=The crosslinguistic study of language acquisition|last1=Newport|first1=Elissa|last2=Meier|first2=Richard|publisher=Lawrence Erlbaum Associates|year=1985|isbn=0898593670|pages=[https://archive.org/details/crosslinguistics0001unse/page/881 881–938]|url=https://archive.org/details/crosslinguistics0001unse/page/881}}</ref>

A central task for the pioneers of sign language linguistics was trying to prove that ASL was a real language and not merely a collection of gestures or "English on the hands." One of the prevailing beliefs at this time was that "real languages" must consist of an arbitrary relationship between form and meaning. Thus, if ASL consisted of signs that had iconic form-meaning relationship, it could not be considered a real language. As a result, iconicity as a whole was largely neglected in research of sign languages for a long time. However, iconicity also plays a role in many spoken languages. Spoken [[Japanese language|Japanese]] for example exhibits many words mimicking the sounds of their potential referents (see [[Japanese sound symbolism]]). Later researchers, thus, acknowledged that natural languages do not need to consist of an arbitrary relationship between form and meaning.<ref>For the history of research on iconicity in sign languages see, for example: Vermeerbergen, Myriam (2006): Past and current trends in sign language research. In: Language & Communication, 26(2). 168-192.</ref> The visual nature of sign language simply allows for a greater degree of iconicity compared to spoken languages as most real-world objects can be described by a prototypical shape (e.g., a table usually has a flat surface), but most real-world objects do not make prototypical sounds that can be mimicked by spoken languages (e.g., tables do not make prototypical sounds). However, sign languages are not fully iconic. On the one hand, there are also many arbitrary signs in sign languages and, on the other hand, the grammar of a sign language puts limits to the degree of iconicity: All known sign languages, for example, express lexical concepts via manual signs. From a truly iconic language one would expect that a concept like smiling would be expressed by mimicking a smile (i.e., by performing a smiling face). All known sign languages, however, do not express the concept of smiling by a smiling face, but by a manual sign.<ref>Bross, Fabian (2020). The clausal syntax of German Sign Language. A cartographic approach. Berlin: Language Science Press. Page 25.</ref>

The [[cognitive linguistics]] perspective rejects a more traditional definition of iconicity as a relationship between linguistic form and a concrete, real-world referent. Rather it is a set of selected correspondences between the form and meaning of a sign.<ref name="Taub 2001">Taub, S. (2001). ''Language from the body''. New York : Cambridge University Press.</ref> In this view, iconicity is grounded in a language user's mental representation ("[[construal]]" in [[cognitive grammar]]). It is defined as a fully grammatical and central aspect of a sign language rather than a peripheral phenomenon.<ref name="Wilcox 2004"/>

The cognitive linguistics perspective allows for some signs to be fully iconic or partially iconic given the number of correspondences between the possible parameters of form and meaning.<ref name="Wilcox 2000"/> In this way, the [[Israeli Sign Language]] (ISL) sign for ''ask'' has parts of its form that are iconic ("movement away from the mouth" means "something coming from the mouth"), and parts that are arbitrary (the handshape, and the orientation).<ref name="Meir 2010"/>

Many signs have [[metaphoric]] mappings as well as iconic or metonymic ones. For these signs there are three-way correspondences between a form, a concrete source and an abstract target meaning. The ASL sign LEARN has this three-way correspondence. The abstract target meaning is "learning". The concrete source is putting objects into the head from books. The form is a grasping hand moving from an open palm to the forehead. The iconic correspondence is between form and concrete source. The metaphorical correspondence is between concrete source and abstract target meaning. Because the concrete source is connected to two correspondences linguistics refer to metaphorical signs as "double mapped".<ref name="Taub 2001"/><ref name="Wilcox 2000"/><ref name="Meir 2010"/>
{{Clear}}

=== Classification ===
{{See also|List of sign languages}}
[[File:Sign language families.svg|thumb|300px|alt=Sign language families I|'''The classification of Sign Language families'''
{{Legend|#5d6a8f|[[French Sign Language family]]}}
{{Legend|#1e2f5d|→[[American Sign Language]] (ASL) cluster}}
{{Legend|#93a1c7|→[[Russian Sign Language]] cluster}}
{{Legend|#a8d3db|→[[Czech Sign Language]] cluster}}
{{Legend|#9c6cd0|[[Danish Sign Language]] family}}
{{Legend|#a596d8|[[Swedish Sign Language family]]}}
{{Legend|#b08660|[[German Sign Language family]]}}
{{Legend|#660066|[[Vietnamese sign languages]] & some Thai and Lao SLs}}
{{Legend|#383834|[[Arab sign-language family]]}}
{{Legend|#99ff00|[[Indo-Pakistani Sign Language]]}}
{{Legend|#ff9691|[[Chinese Sign Language]]}}
{{Legend|#bd4b31|[[Japanese Sign Language family]]}}
{{Legend|#4b874b|[[BANZSL]] family (British, Australian and New Zealand Sign Language)}}
{{Legend|#1c5e31|[[South African Sign Language]] (within the BANZSL family)}}
{{Legend|#fff200|Isolated languages}}
{{Legend|#e6e6e6|No data}}]]Sign languages may be classified by how they arise.

In non-signing communities, [[home sign]] is not a full language, but closer to a [[pidgin]]. Home sign is amorphous and generally idiosyncratic to a particular family, where a deaf child does not have contact with other deaf children and is not educated in sign. Such systems are not generally passed on from one generation to the next. Where they are passed on, [[creole genesis|creolization]] would be expected to occur, resulting in a full language.  However, home sign may also be closer to full language in communities where the hearing population has a gestural mode of language; examples include various [[Australian Aboriginal sign languages]] and gestural systems across West Africa, such as [[Mofu-Gudur Sign Language|Mofu-Gudur]] in Cameroon.

A [[village sign language]] is a local indigenous language that typically arises over several generations in a relatively insular community with a high incidence of deafness, and is used both by the deaf and by a significant portion of the hearing community, who have deaf family and friends.<ref>{{cite book |last1= Meir |first1= Irit |last2= Sandler |first2= Wendy |last3= Padden |first3= Carol |author-link3= Carol Padden |last4= Aronoff |first4= Mark |author-link4= Mark Aronoff |year= 2010 |chapter= Chapter 18: Emerging sign languages |chapter-url= http://sandlersignlab.haifa.ac.il/html/html_eng/pdf/EMERGING_SIGN_LANGUAGES.pdf |editor1-last= Marschark |editor1-first= Marc |editor2-last= Spencer |editor2-first= Patricia Elizabeth |title= Oxford Handbook of Deaf Studies, Language, and Education |url= https://books.google.com/books?id=0mmJAgAAQBAJ |volume= 2 |location= New York |publisher= [[Oxford University Press]] |isbn= 978-0-19-539003-2 |oclc= 779907637 |access-date= 2016-11-05 |archive-date= 2023-01-14 |archive-url= https://web.archive.org/web/20230114125751/https://books.google.com/books?id=0mmJAgAAQBAJ |url-status= live }}</ref> The most famous of these is probably the extinct [[Martha's Vineyard Sign Language]] of the U.S., but there are also numerous village languages scattered throughout Africa, Asia, and America.

[[Deaf-community sign language]]s, on the other hand, arise where deaf people come together to form their own communities. These include school sign, such as [[Nicaraguan Sign Language]], which develop in the student bodies of deaf schools which do not use sign as a language of instruction, as well as community languages such as [[Bamako Sign Language]], which arise where generally uneducated deaf people congregate in urban centers for employment. At first, Deaf-community sign languages are not generally known by the hearing population, in many cases not even by close family members. However, they may grow, in some cases becoming a language of instruction and receiving official recognition, as in the case of ASL.

Both contrast with [[speech taboo|speech-taboo]] languages such as the various [[Aboriginal Australian sign languages]], which are developed by the hearing community and only used secondarily by the deaf. It is doubtful whether most of these are languages in their own right, rather than manual codes of spoken languages, though a few such as [[Yolngu Sign Language]] are independent of any particular spoken language. Hearing people may also develop sign to communicate with users of other languages, as in [[Plains Indian Sign Language]]; this was a contact signing system or [[pidgin]] that was evidently not used by deaf people in the Plains nations, though it presumably influenced home sign.

[[Language contact]] and creolization is common in the development of sign languages, making clear family classifications difficult– it is often unclear whether lexical similarity is due to borrowing or a common parent language, or whether there was one or several parent languages, such as several village languages merging into a Deaf-community language. Contact occurs between sign languages, between sign and spoken languages ([[contact sign]], a kind of pidgin), and between sign languages and [[gesture|gestural systems]] used by the broader community. For example, [[Adamorobe Sign Language]], a village sign language of Ghana, may be related to the "gestural trade jargon used in the markets throughout West Africa", in vocabulary and [[areal feature]]s including prosody and phonetics.<ref>Frishberg, Nancy (1987). "Ghanaian Sign Language." In: Cleve, J. Van (ed.), ''Gallaudet encyclopaedia of deaf people and deafness''. New York: McGraw-Hill Book Company. {{ISBN|9780070792296}}</ref><ref name="Wittmann, H. 1991">Wittmann, H. (1991). Classification linguistique des langues signées non vocalement. ''Revue québécoise de linguistique théorique et appliquée'', 10(1), 88.</ref>

[[File:Lao sign language 025.jpg|thumb|Young students learn some words of [[Lao sign language]] from Suliphone, a deaf artist. This was one of several activities at a school book party sponsored by Big Brother Mouse, a literacy project in [[Laos]] where Suliphone works.]]
* [[British Sign Language|BSL]], [[Auslan]] and [[NZSL]] are usually considered to be a language known as [[BANZSL]]. [[Maritime Sign Language]] and [[South African Sign Language]] are also related to BSL.<ref>See Gordon (2008), under nsr {{cite web |url=http://www.ethnologue.com/show_language.asp?code=nsr |title=Maritime Sign Language |access-date=2011-06-01 |url-status=live |archive-url=https://web.archive.org/web/20110604014547/http://www.ethnologue.com/show_language.asp?code=nsr |archive-date=2011-06-04 }} and sfs {{cite web |url=http://www.ethnologue.com/show_language.asp?code=sfs |title=South African Sign Language |access-date=2008-09-19 |url-status=live |archive-url=https://web.archive.org/web/20080921104537/http://www.ethnologue.com/show_language.asp?code=sfs |archive-date=2008-09-21 }}.</ref>
* [[Danish Sign Language]] and its descendants [[Norwegian Sign Language]] and [[Icelandic Sign Language]] are largely mutually intelligible with [[Swedish Sign Language]]. [[Finnish Sign Language]] and [[Portuguese Sign Language]] derive from Swedish SL, though with local admixture in the case of mutually unintelligible Finnish SL.{{clarify|date=September 2014}} Danish SL has French SL influence and Wittmann (1991) places them in that family,<ref name="Wittmann, H. 1991"/> though he proposes that Swedish, Finnish, and Portuguese SL are instead related to [[British Sign Language]].
* [[Swedish Sign Language family|Swedish Sign Language Family]] includes the following languages: [[Swedish Sign Language]], [[Finnish Sign Language]], [[Finland-Swedish Sign Language]], [[Portuguese Sign Language]], [[Eritrean Sign Language]] and the [[Cape Verdian Sign Language]],<ref>{{Cite web |title=State of Eritrea |url=https://africansignlanguagesresourcecenter.com/eritrea/ |access-date=2024-05-13 |website=African Sign Languages Resource Center |language=en-US |archive-date=2024-05-13 |archive-url=https://web.archive.org/web/20240513205208/https://africansignlanguagesresourcecenter.com/eritrea/ |url-status=live }}</ref><ref>{{Cite book |last=Jepsen |first=Julie |title=Sign Languages of the World: a Comparative Handbook |publisher=De Gruyter |year=2015}}</ref><ref name=":0">{{Cite web |title=Cape Verde |url=https://africansignlanguagesresourcecenter.com/cape-verde/ |access-date=2024-05-13 |website=African Sign Languages Resource Center |language=en-US |archive-date=2024-05-13 |archive-url=https://web.archive.org/web/20240513193111/https://africansignlanguagesresourcecenter.com/cape-verde/ |url-status=live }}</ref><ref>{{Cite web |last=Pinto |first=Mariana Correia |date=2017-11-14 |title=O que todos devíamos saber sobre língua gestual (em dez pontos) |url=https://www.publico.pt/2017/11/14/p3/noticia/o-que-todos-deviamos-saber-sobre-lingua-gestual-em-dez-pontos-1828846 |access-date=2024-05-13 |website=PÚBLICO |language=pt |archive-date=2024-05-13 |archive-url=https://web.archive.org/web/20240513195919/https://www.publico.pt/2017/11/14/p3/noticia/o-que-todos-deviamos-saber-sobre-lingua-gestual-em-dez-pontos-1828846 |url-status=live }}</ref> although some reports also say that the [[São Tomé and Príncipe Sign Language]] is largely intelligible with Portuguese Sign.<ref name=":02">{{Cite web |title=Democratic Republic of São Tomé and Príncipe |url=https://africansignlanguagesresourcecenter.com/sao-tome-and-principe/ |access-date=2024-05-13 |website=African Sign Languages Resource Center |language=en-US |archive-date=2024-05-13 |archive-url=https://web.archive.org/web/20240513201434/https://africansignlanguagesresourcecenter.com/sao-tome-and-principe/ |url-status=live }}</ref>
* [[Indian Sign Language]] (ISL) is similar to [[Pakistani Sign Language]].
* [[Japanese Sign Language]], [[Taiwanese Sign Language]] and [[Korean Sign Language]] are thought to be members of a [[Japanese Sign Language family]].<ref>Fischer, Susan D. ''et al.'' (2010). "Variation in East Asian Sign Language Structures" in {{Google books|xI0uqGyrsN8C|''Sign Languages,''|page=499}}</ref>
* [[French Sign Language family]]. There are a number of sign languages that emerged from [[French Sign Language]] (LSF), or are the result of language contact between local community sign languages and LSF. These include: [[French Sign Language]], [[Italian Sign Language]], [[Quebec Sign Language]] (LSQ), [[American Sign Language]], [[Irish Sign Language]], [[Russian Sign Language]], [[Dutch Sign Language]] (NGT), [[Spanish Sign Language]], [[Mexican Sign Language]], [[Brazilian Sign Language|Brazilian Sign Language (LIBRAS)]], [[Catalan Sign Language]], [[Ukrainian Sign Language]], [[Austrian Sign Language]] (along with its twin [[Hungarian Sign Language]] and its offspring [[Czech Sign Language]]) and others.
** A subset of this group includes languages that have been heavily influenced by American Sign Language (ASL), or are regional varieties of ASL. [[Bolivian Sign Language]] is sometimes considered a dialect of ASL. [[Thai Sign Language]] is a [[mixed language]] derived from ASL and the native sign languages of Bangkok and Chiang Mai, and may be considered part of the ASL family. Others possibly influenced by ASL include [[Ugandan Sign Language]], [[Kenyan Sign Language]], [[Philippine Sign Language]] and [[Malaysian Sign Language]].
** According to an SIL report,<ref>{{Cite web|date=2012-01-14|title=SIL Electronic Survey Reports: The signed languages of Eastern Europe|url=http://www.sil.org/silesr/abstract.asp?ref=2005-026|url-status=live|access-date=2021-08-23|archive-url=https://web.archive.org/web/20120114060622/http://www.sil.org/silesr/abstract.asp?ref=2005-026|archive-date=2012-01-14}}</ref> the sign languages of Russia, Moldova and Ukraine share a high degree of lexical similarity and may be dialects of one language, or distinct related languages. The same report suggested a "cluster" of sign languages centered around [[Czech Sign Language]], [[Hungarian Sign Language]] and [[Slovak Sign Language]]. This group may also include [[Romanian Sign Language|Romanian]], [[Bulgarian Sign Language|Bulgarian]], and [[Polish Sign Language|Polish]] sign languages.
* [[German Sign Language]] (DGS) gave rise to [[Polish Sign Language]]; it also at least strongly influenced [[Israeli Sign Language]], though it is unclear whether the latter derives from DGS or from [[Austrian Sign Language]], which is in the French family.
* The southern dialect of [[Chinese Sign Language]] gave rise to [[Hong Kong Sign Language]], used in Hong Kong and Macau
* [[Lyons Sign Language]] may be the source of [[Flemish Sign Language]] (VGT) though this is unclear.
* Sign languages of [[Jordanian Sign Language|Jordan]], Lebanon, Syria, Palestine, and Iraq (and possibly [[Saudi Sign Language|Saudi Arabia]]) may be part of a [[sprachbund]], or may be one dialect of a larger [[Eastern Arabic Sign Language]].
* Known [[Language isolate#Sign language isolates|isolates]] include [[Nicaraguan Sign Language]], [[Turkish Sign Language]], [[Armenian Sign Language]], [[Kata Kolok]], [[Al-Sayyid Bedouin Sign Language]] and [[Providence Island Sign Language]].

The only comprehensive classification along these lines going beyond a simple listing of languages dates back to 1991.<ref>Henri Wittmann (1991). The classification is said to be typological satisfying Jakobson's condition of genetic interpretability.</ref> The classification is based on the 69 sign languages from the 1988 edition of [[Ethnologue]] that were known at the time of the 1989 conference on sign languages in Montreal and 11 more languages the author added after the conference.{{refn |Wittmann's classification went into Ethnologue's database where it is still cited.<ref>{{cite web |editor1=Simons, Gary F. |editor2=Charles D. Fennig |year=2018 |title=Bibliography of Ethnologue Data Sources |work=Ethnologue: Languages of the World |edition=21st |publisher=SIL International |url=http://www.ethnologue.com/ethno_docs/bibliography.asp |access-date=2008-09-19 |url-status=live |archive-url=https://web.archive.org/web/20080725072840/http://www.ethnologue.com/ethno_docs/bibliography.asp |archive-date=2008-07-25 }}</ref> The subsequent edition of Ethnologue in 1992 went up to 81 sign languages, ultimately adopting Wittmann's distinction between primary and alternate sign languages (going back ultimately to Stokoe 1974) and, more vaguely, some other traits from his analysis. The 2013 version (17th edition) of [[Ethnologue]] is now up to 137 sign languages.}}

{| class = "wikitable"
|+ Wittmann classification of sign languages
!
! Primary<br />language
! Primary<br />group
! Auxiliary<br />language
! Auxiliary<br />group
|-
| Prototype-A<ref name=pro-A/>
|5<!--not 7: the other two are Chinese and Egyptian logograms, not sign languages at all-->
|1
|7
|2
|-
| Prototype-R<ref name=pro-R/>
|18
|1
|1
|–
|-
| [[BANZSL|BSL-derived]]
|8
|–
|–
|–
|-
| [[German Sign Language family|DGS-derived]]
|1 or 2
|–
|–
|–
|-
| [[Japanese Sign Language family|JSL-derived]]
|2
|
–
|–
|–
|-
| [[French Sign Language family|LSF-derived]]
|30
|–
|–
|–
|-
| [[Lyons Sign Language|LSG]]-derived
|
[[Flemish Sign Language|1?]]
|–
|–
|–
|}

In his classification, the author distinguishes between primary and auxiliary sign languages<ref>Wittmann adds that this taxonomic criterion is not really applicable with any scientific rigor: Auxiliary sign languages, to the extent that they are full-fledged natural languages (and therefore included in his survey) at all, are mostly used by the deaf as well, and some primary sign languages (such as ASL and [[Adamorobe Sign Language]]) have acquired auxiliary usages.</ref> as well as between single languages and names that are thought to refer to more than one language.<ref>Wittmann includes in this class [[Australian Aboriginal sign languages]] (at least 14 different languages), [[Monastic sign language]], Thai Hill-Country sign languages (possibly including languages in Vietnam and Laos), and [[Sri Lankan sign languages]] (14 deaf schools with different sign languages).</ref> The prototype-A class of languages includes all those sign languages that seemingly cannot be derived from any other language.<ref name="pro-A">These are [[Adamorobe Sign Language]], [[Armenian Sign Language]], [[Australian Aboriginal sign languages]], Hindu [[mudra]], the [[Monastic sign languages]], [[Martha's Vineyard Sign Language]], [[Plains Indian Sign Language]], [[Urubú-Kaapor Sign Language]], [[Chinese Sign Language]], [[Indo-Pakistani Sign Language]] (Pakistani SL is said to be R, but Indian SL to be A, though they are the same language), [[Japanese Sign Language]], and maybe the various [[Thai Hill-Country sign languages]], [[French Sign Language]], [[Lyons Sign Language]], and [[Mayan sign languages|Nohya Maya Sign Language]]. Wittmann also includes, bizarrely, Chinese characters and Egyptian hieroglyphs.</ref> Prototype-R languages are languages that are remotely modelled on a prototype-A language (in many cases thought to have been French Sign Language) by a process Kroeber (1940) called "[[stimulus diffusion]]".<ref name=pro-R>These are [[Providencia Island Sign Language|Providencia Island]], [[Kod Tangan Bahasa Malaysia]] (manually signed Malay), [[German Sign Language|German]], [[Ecuadorian Sign Language|Ecuadoran]], [[Salvadoran Sign Language|Salvadoran]], [[Gestuno]], [[Indo-Pakistani Sign Language|Indo-Pakistani]] (Pakistani SL is said to be R, but Indian SL to be A, though they are the same language), [[Kenyan Sign Language|Kenyan]], [[Brazilian Sign Language|Brazilian]], [[Spanish Sign Language|Spanish]], [[Nepali Sign Language|Nepali]] (with possible admixture), [[Penang Sign Language|Penang]], [[Rennellese Sign Language|Rennellese]], [[Saudi Sign Language|Saudi]], the various [[Sri Lankan sign languages]], and perhaps BSL, [[Peruvian Sign Language|Peruvian]], [[Tijuana Sign Language|Tijuana]] (spurious), [[Venezuelan Sign Language|Venezuelan]], and [[Nicaraguan Sign Language|Nicaraguan]] sign languages.</ref> The families of [[BANZSL|BSL]], [[German Sign Language|DGS]], [[Japanese Sign Language|JSL]], [[French Sign Language|LSF]] (and possibly [[Lyons Sign Language|LSG]]) were the products of [[creolization]] and [[relexification]] of prototype languages.<ref>Wittmann's references on the subject, besides his own work on [[creolization]] and [[relexification]] in spoken languages, include papers such as Fischer (1974, 1978), Deuchar (1987) and Judy Kegl's pre-1991 work on creolization in sign languages.</ref> Creolization is seen as enriching overt morphology in sign languages, as compared to reducing overt morphology in spoken languages.<ref>Wittmann's explanation for this is that models of acquisition and transmission for sign languages are not based on any typical parent-child relation model of direct transmission which is inducive to variation and change to a greater extent. He notes that sign creoles are much more common than vocal creoles and that we can't know on how many successive creolizations prototype-A sign languages are based prior to their historicity.{{Clarify|date=February 2011}}</ref>

=== Typology ===
{{See also|Linguistic typology}}

Linguistic typology (going back to [[Edward Sapir]]) is based on word structure and distinguishes [[Morphology (linguistics)|morphological]] classes such as [[Agglutination|agglutinating]]/concatenating, [[Inflexion|inflectional]], polysynthetic, incorporating, and isolating ones.

Sign languages vary in word-order typology. For example, Austrian Sign Language, Japanese Sign Language and [[Indo-Pakistani Sign Language]] are [[Subject-object-verb]] while ASL is [[Subject-verb-object]]. Influence from the surrounding spoken languages is not improbable.

Sign languages tend to be incorporating classifier languages, where a classifier handshape representing the object is incorporated into those transitive verbs which allow such modification. For a similar group of intransitive verbs (especially motion verbs), it is the subject which is incorporated. Only in a very few sign languages (for instance Japanese Sign Language) are agents ever incorporated. In this way, since subjects of intransitives are treated similarly to objects of transitives, incorporation in sign languages can be said to follow an ergative pattern.

Brentari<ref name="Brentari1998">Brentari, Diane (1998) ''A prosodic model of sign language phonology''. Cambridge, Massachusetts: MIT Press</ref><ref>{{cite book |last1=Brentari |first1=Diane |title=Modality and Structure in Signed and Spoken Languages |isbn=9780511486777 |chapter=Modality differences in sign language phonology and morphophonemics |year=2002 |pages=35–36 |doi=10.1017/CBO9780511486777.003 |editor1=P. Meier |editor2=Kearsy Cormier |editor3=David Quinto-Pozos}}</ref> classifies sign languages as a whole group determined by the medium of communication (visual instead of auditory) as one group with the features monosyllabic and polymorphemic. That means, that one syllable (i.e. one word, one sign) can express several morphemes, e.g., subject and object of a verb determine the direction of the verb's movement (inflection).

Another aspect of typology that has been studied in sign languages is their systems for [[Cardinal number (linguistics)|cardinal numbers]].<ref>{{cite journal|last1=Ulrike|first1=Zeshan|last2=Escobedo Delgado|first2=Cesar Ernesto|last3=Dikyuva|first3=Hasan|last4=Panda|first4=Sibaji|last5=de Vos|first5=Connie|title=Cardinal numerals in rural sign languages: Approaching cross-modal typology|journal=Linguistic Typology|volume=17|issue=3|year=2013|url=https://www.researchgate.net/publication/261473038|doi=10.1515/lity-2013-0019|hdl=11858/00-001M-0000-0013-B2E1-B|s2cid=145616039|hdl-access=free}}</ref> Typologically significant differences have been found between sign languages.

=== Acquisition ===
{{See also|Language acquisition}}

Children who are exposed to a sign language from birth will acquire it, just as hearing children acquire their native spoken language.<ref>{{cite book|last=Emmorey|first=Karen|title=Language, Cognition, and the Brain|year=2002|publisher=Lawrence Erlbaum Associates|location=Mahwah, NJ}}</ref> In a study done at McGill University, they found that American Sign Language users who acquired the language natively (from birth) performed better when asked to copy videos of ASL sentences than ASL users who acquired the language later in life. They also found that there are differences in the grammatical morphology of ASL sentences between the two groups, all suggesting that there is a very important critical period in learning signed languages.<ref>{{Cite web|url=http://www.acfos.org/publication/ourarticles/pdf/acfos1/mayberry.pdf|title=The Critical Period for Language Acquisition and The Deaf Child's Language Comprehension: A Psycholinguistic Approach|last=Mayberry|first=Rachel|website=ACFOS|url-status=live|archive-url=https://web.archive.org/web/20171201072124/http://www.acfos.org/publication/ourarticles/pdf/acfos1/mayberry.pdf|archive-date=2017-12-01}}</ref>

The acquisition of non-manual features follows an interesting pattern: When a word that always has a particular non-manual feature associated with it (such as a [[Wh question|wh-question]] word) is learned, the non-manual aspects are attached to the word but do not have the flexibility associated with adult use. At a certain point, the non-manual features are dropped and the word is produced with no facial expression. After a few months, the non-manuals reappear, this time being used the way adult signers would use them.<ref>{{cite book|title=Advances in the Sign Language Development of Deaf Children|year=2005|publisher=Oxford University Press|location=Cary, NC|isbn=978-0-19-803996-9|pages=262–290|author=Reilly, Judy|editor1=Brenda Schick |editor2=Marc Marschack |editor3=Patricia Elizabeth Spencer |chapter=How Faces Come to Serve Grammar: The Development of Nonmanual Morphology in American Sign Language}}</ref>

=== Written forms ===
{{anchor|Notation}}<!-- [[Sign language notation]] redirects here -->
Sign languages do not have a traditional or formal written form. Many deaf people do not see a need to write their own language.<ref>{{cite journal | last1 = Hopkins | first1 = Jason | year = 2008 | title = Choosing how to write sign language: a sociolinguistic perspective | journal = [[International Journal of the Sociology of Language]] | volume = 2008 | issue = 192| pages = 75–90 | doi=10.1515/ijsl.2008.036| s2cid = 145429638 }}</ref>

Several ways to represent sign languages in written form have been developed.

* [[Stokoe notation]], devised by Dr. [[William Stokoe]] for his 1965 ''Dictionary of American Sign Language'',<ref name="StokoeWilliam">[[William Stokoe|Stokoe, William C.]]; [[Dorothy C. Casterline]]; [[Carl G. Croneberg]]. 1965. ''A dictionary of American sign language on linguistic principles''. Washington, D.C.: Gallaudet College Press</ref> is an abstract [[phonemic]] notation system. Designed specifically for representing the use of the hands, it has no way of expressing facial expression or other non-manual features of sign languages. However, it was designed for research, particularly in a dictionary, not for general use.
* The [[Hamburg Notation System]] (HamNoSys), developed in the early 1990s, is a detailed phonetic system, not designed for any one sign language, and intended as a transcription system for researchers rather than as a practical script.
* [[David J. Peterson]] has attempted to create a phonetic transcription system for signing that is [[ASCII]]-friendly known as the [https://dedalvs.com/slipa.html Sign Language International Phonetic Alphabet (SLIPA)].
* [[SignWriting]], developed by Valerie Sutton in 1974, is a system for representing sign languages phonetically (including [[mouthing]], facial expression and dynamics of movement). The script is sometimes used for detailed research, language documentation, as well as publishing texts and works in sign languages.
* [[si5s]] is another orthography which is largely phonemic. However, a few signs are [[logogram|logographs]] and/or [[ideograph]]s due to regional variation in sign languages.
* [[ASL-phabet]] is a system designed primarily for education of deaf children by Dr. [[Samuel James Supalla|Sam Supalla]] which uses a minimalist collection of symbols in the order of Handshape-Location-Movement. Many signs can be written the same way ([[homograph]]).
*The Alphabetic Writing System for sign languages ({{Lang|es|Sistema de escritura alfabética}}, SEA, by its Spanish name and acronym), developed by linguist Ángel Herrero Blanco and two deaf researchers, Juan José Alfaro and Inmacualada Cascales, was published as a book in 2003<ref>{{Cite book|title=Escritura alfabética de la Lengua de Signos Española : once lecciones|last=Herrero Blanco, Ángel L.|date=2003|publisher=Publicaciones de la Universidad de Alicante|others=Alfaro, Juan José,, Cascales, Inmaculada|isbn=9781282574960|location=San Vicente del Raspeig [Alicante]|oclc=643124997}}</ref> and made accessible in [[Spanish Sign Language]] on-line.<ref>{{Cite web|url=http://www.cervantesvirtual.com/seccion/signos/psegundonivel.jsp?seccion=signos&conten=materiales&pagina=cat_materiales1&tit3=Lecciones+de+escritura+alfab%25E9tica+de+LSE|title=Biblioteca de signos – Materiales|website=www.cervantesvirtual.com|access-date=2019-07-07|archive-date=2020-09-06|archive-url=https://web.archive.org/web/20200906213725/http://www.cervantesvirtual.com/seccion/signos/psegundonivel.jsp?seccion=signos&conten=materiales&pagina=cat_materiales1&tit3=Lecciones+de+escritura+alfab%E9tica+de+LSE|url-status=dead}}</ref> This system makes use of the letters of the Latin alphabet with a few diacritics to represent sign through the morphemic sequence S L C Q D F (bimanual sign, place, contact, handshape, direction and internal form). The resulting words are meant to be read by signing. The system is designed to be applicable to any sign language with minimal modification and to be usable through any medium without special equipment or software. Non-manual elements can be encoded to some extent, but the authors argue that the system does not need to represent all elements of a sign to be practical, the same way written oral language does not. The system has seen some updates which are kept publicly on a wiki page.<ref>{{Cite web|url=http://wiki.apertium.org/wiki/Traductor_de_espa%C3%B1ol_a_LSE|title=Traductor de español a LSE – Apertium|website=wiki.apertium.org|access-date=2019-07-07|archive-date=2019-07-03|archive-url=https://web.archive.org/web/20190703071935/http://wiki.apertium.org/wiki/Traductor_de_espa%C3%B1ol_a_LSE|url-status=live}}</ref> The Center for Linguistic Normalization of Spanish Sign Language has made use of SEA to transcribe all signs on its dictionary.<ref>{{Cite web|url=http://sid.usal.es/libros/discapacidad/20740/8-7-2/diccionario-normativo-de-la-lengua-de-signos-espanola-dvd.aspx|title=Diccionario normativo de la lengua de signos española ... (SID)|website=sid.usal.es|language=es|access-date=2019-07-07|archive-date=2019-07-07|archive-url=https://web.archive.org/web/20190707142030/http://sid.usal.es/libros/discapacidad/20740/8-7-2/diccionario-normativo-de-la-lengua-de-signos-espanola-dvd.aspx|url-status=dead}}</ref>

So far, there is no consensus regarding the written form of sign language.  Except for SignWriting, none are widely used. Maria Galea writes that SignWriting "is becoming widespread, uncontainable and untraceable. In the same way that works written in and about a well developed writing system such as the Latin script, the time has arrived where SW is so widespread, that it is impossible in the same way to list all works that have been produced using this writing system and that have been written about this writing system."<ref name="GaleaLinguistic">{{cite book
 |last        = Galea
 |first       = Maria
 |title       = SignWriting (SW) of Maltese Sign Language (LSM) and its development into an orthography: Linguistic considerations
 |year        = 2014
 |type        = Ph.D. dissertation
 |publisher   = University of Malta
 |location    = Malta
 |url         = https://www.academia.edu/10451785
 |access-date  = 4 February 2015
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20180513202709/http://www.academia.edu/10451785/SignWriting_SW_of_Maltese_Sign_Language_LSM_and_its_development_into_an_orthography_Linguistic_considerations
 |archive-date = 13 May 2018
}}</ref> For example, in 2015 at the [[Federal University of Santa Catarina]], João Paulo Ampessan wrote his linguistics master's dissertation in Brazilian Sign Language using Sutton SignWriting. In his dissertation, "The Writing of Grammatical Non-Manual Expressions in Sentences in LIBRAS Using the SignWriting System," Ampessan states that "the data indicate the need for [non-manual expressions] usage in writing sign language".<ref>Ampessan, João Paulo. "The Writing of Grammatical Non-Manual Expressions in Sentences in LIBRAS Using the SignWriting System." ''Universidade Federal de Santa Catarina'', 2015. [https://web.archive.org/web/20210129185100/https://repositorio.ufsc.br/bitstream/handle/123456789/180688/351070.pdf Archived] from [https://repositorio.ufsc.br/bitstream/handle/123456789/180688/351070.pdf the original] on 29 January 2021.</ref>

=== Sign perception ===
For a native signer, sign [[Categorical perception|perception]] influences how the mind makes sense of their visual language experience. For example, a handshape may vary based on the other signs made before or after it, but these variations are arranged in perceptual categories during its development.  The mind detects handshape contrasts but groups similar handshapes together in one category.<ref>{{cite journal |author1=Morford, Jill P. |author2=Staley, Joshua |author3=Burns, Brian |date=Fall 2010 |url=http://dsdj.gallaudet.edu/assets/section/section2/entry94/DSDJ_entry94.pdf |title=Seeing Signs: Language Experience and Handshape Perception |others=Videography by Jo Santiago and Brian Burns |journal=Deaf Studies Digital Journal |issue=2 |access-date=2011-12-14 |url-status=live |archive-url=https://web.archive.org/web/20120111142013/http://dsdj.gallaudet.edu/assets/section/section2/entry94/DSDJ_entry94.pdf |archive-date=2012-01-11 }}</ref><ref>{{cite journal | last1 = Kuhl | first1 = P | year = 1991 | title = Human adults and human infants show a 'perceptual magnet effect' for the prototypes of speech categories, monkeys do not | journal = Perception and Psychophysics | volume = 50 | issue = 2| pages = 93–107 | doi=10.3758/bf03212211| pmid = 1945741 | doi-access = free }}</ref><ref>{{cite journal | last1 = Morford | first1 = J. P. | last2 = Grieve-Smith | first2 = A. B. | last3 = MacFarlane | first3 = J. | last4 = Staley | first4 = J. | last5 = Waters | first5 = G. S. | year = 2008| title = Effects of language experience on the perception of American Sign Language | journal = Cognition | volume = 109 | issue = 41–53| pages = 41–53 | doi=10.1016/j.cognition.2008.07.016| pmid = 18834975 | pmc = 2639215 }}</ref> Different handshapes are stored in other categories.  The mind ignores some of the similarities between different perceptual categories, at the same time preserving the visual information within each perceptual category of handshape variation.