Social theories Code-switching relates to, and sometimes
indexes social-group membership in bilingual and multilingual communities. Some sociolinguists describe the relationships between code-switching behaviours and
class,
ethnicity, and other social positions. In addition, scholars in
interactional linguistics and
conversation analysis have studied code-switching as a means of structuring speech in interaction. Some discourse analysts, including conversation analyst
Peter Auer, suggest that code-switching does not simply reflect social situations, but that it is a means to create social situations.
Markedness model The Markedness model, developed by
Carol Myers-Scotton, is one of the more complete theories of code-switching motivations. It posits that language users are
rational and choose to speak a language that clearly marks their rights and obligations, relative to other speakers, in the conversation and its setting. When there is no clear,
unmarked language choice, speakers practice code-switching to explore possible language choices. Many sociolinguists, however, object to the Markedness Model's postulation that language-choice is entirely rational.
Sequential analysis Scholars of conversation analysis such as Peter Auer and
Li Wei argue that the social motivation behind code-switching lies in the way code-switching is structured and managed in conversational interaction; in other words, the question of why code-switching occurs cannot be answered without first addressing the question of how it occurs. Using conversation analysis (CA), these scholars focus their attention on the sequential implications of code-switching. That is, whatever language a speaker chooses to use for a conversational turn, or part of a turn, impacts the subsequent choices of language by the speaker as well as the hearer. Rather than focusing on the social values inherent in the languages the speaker chooses ("brought-along meaning"), the analysis concentrates on the meaning that the act of code-switching itself creates ("brought-about meaning").
Diglossia In a diglossic situation, some topics are better suited to the use of one language over another.
Joshua Fishman proposes a domain-specific code-switching model (later refined by Blom and
Gumperz) wherein bilingual speakers choose which code to speak depending on where they are and what they are discussing. For example, a child who is a bilingual Spanish-English speaker might speak Spanish at home and English in class, but Spanish at recess.
Linguistic theories In studying the syntactic and
morphological patterns of language alternation, linguists have postulated specific
grammatical rules and specific syntactic boundaries for where code-switching might occur.
Constraint-based model: Poplack (1980) Shana Poplack's model of code-switching is an influential theory of the grammar of code-switching. On the contrary, cases like the noun phrases
the casa white and
the blanca house are ruled out because the combinations are ungrammatical in at least one of the languages involved. Spanish noun phrases are made up of determiners, then nouns, then adjectives, while the adjectives come before the nouns in English noun phrases.
The casa white is ruled out by the equivalence constraint because it does not obey the syntactic rules of English, and
the blanca house is ruled out because it does not follow the syntactic rules of Spanish. The equivalence constraint would also rule out switches that occur commonly in languages, as when Hindi postpositional phrases are switched with English prepositional phrases like in the sentence: "John gave a book
ek larakii ko" ("John gave a book
to a girl"). The phrase
ek larakii ko is literally translated as
a girl to, making it ungrammatical in English, and yet this is a sentence that occurs in English-Hindi code-switching despite the requirements of the equivalence constraint. Although the model has been challenged with counter-examples collected by other researchers, there is a conclusion that most agree on. The conclusion is that the practice of code-switching demonstrates grammatical proficiency of an equivalent level as a monolingual speaker's speech competence, unlike the claims that code-switching reflects incompetence in either of the two languages of a bilingual speaker.
Matrix language-frame model Carol Myers-Scotton's Matrix Language-Frame (MLF) model is the dominant model of insertional code-switching. According to the
Blocking Hypothesis, in Matrix Language + Embedded Language constituents, a blocking filter blocks any Embedded Language content morpheme which is not congruent with the Matrix Language with respect to three levels of abstraction regarding subcategorization. "Congruence" is used in the sense that two entities, linguistic categories in this case, are congruent if they correspond in respect of relevant qualities. The three levels of abstraction are: • Even if the Embedded Language realizes a given grammatical category as a content morpheme, if it is realized as a system morpheme in the Matrix Language, the Matrix Language blocks the occurrence of the Embedded Language content morpheme. (A content morpheme is often called an "open-class" morpheme, because they belong to categories that are open to the invention of arbitrary new items. They can be made-up words like "smurf", "nuke", "byte", etc. and can be nouns, verbs, adjectives, and some prepositions. A system morpheme, e.g. function words and inflections, expresses the relation between content morphemes and does not assign or receive thematic roles.) • The Matrix Language also blocks an Embedded Language content morpheme in these constituents if it is not congruent with a Matrix Language content morpheme counterpart in terms of
theta role assignment. • Congruence between Embedded Language content morphemes and Matrix Language content morphemes is realized in terms of their discourse or
pragmatic functions.
Examples {{verse translation {{verse translation Example 1 is consistent with the Blocking Hypothesis and the system content morpheme criteria, so the prediction is that the Hindi or
Urdu equivalents are also content morphemes. Sometimes non-congruence between counterparts in the Matrix Language and Embedded Language can be circumvented by accessing bare forms. "Cell" is a bare form and so the thematic role of "cell" is assigned by the verb
-wek- 'put in/on'; this means that the verb is a content morpheme. The
Embedded Language Island Trigger Hypothesis states that when an Embedded Language morpheme appears which is not permitted under either the Matrix Language Hypothesis or Blocking Hypothesis, it triggers the inhibition of all Matrix Language accessing procedures and completes the current constituent as an Embedded Language island. Embedded Language islands consist only of Embedded Language morphemes and are well-formed by Embedded Language grammar, but they are inserted in the Matrix Language frame. Therefore, Embedded Language islands are under the constraint of Matrix Language grammar. • Swahili/English • Swahili/English Example 1 is ungrammatical (indicated by the leading asterisk) because "your" is accessed, so the Embedded Language Island Trigger Hypothesis predicts that it must be followed by an English head (e.g., "your letter") as an Embedded Language island. The reason is that possessive adjectives are system morphemes. We see the same thing happen in example 2, which is therefore ungrammatical. However, the correct way to finish the sentence is not "for wewe", switching back to Swahili; rather, it should end with "for you", which would be an Embedded Language island. The
Embedded Language Implicational Hierarchy Hypothesis can be stated as two sub-hypotheses: • The farther a constituent is from the main arguments of the sentence, the freer it is to appear as an Embedded Language island. • The more formulaic in structure a constituent is, the more likely it is to appear as an Embedded Language island. Stated more strongly, choice of any part of an idiomatic expression will result in an Embedded Language island. The approach focuses on the repudiation of any rule or principle which explicitly refers to code-switching itself. This approach does not recognize or accept terms such as "matrix language", "embedded language", or "language frame", which are typical in constraint-based approaches such as the MLF Model. Rather than posit constraints specific to language alternation, as in traditional work in the field, MacSwan advocates that mixed utterances be analyzed with a focus on the specific and unique linguistic contributions of each language found in a mixed utterance. Because these analyses draw on the full range of linguistic theory, and each data set presents its own unique challenges, a much broader understanding of linguistics is generally needed to understand and participate in this style of codeswitching research. For example, Cantone and MacSwan (2009) analyzed word order differences for nouns and adjectives in Italian-German codeswitching using a typological theory of Cinque that had been independently proposed in the syntax literature; their account derives the word order facts of Italian-German codeswitching from underlying differences between the two languages, according to Cinque's theory. Myers-Scotton and MacSwan debated the relative merits of their approaches in a series of exchanges published in 2005 in
Bilingualism: Language and Cognition, issues 8(1) and 8(2).
Other theories Much remains to be done before a more complete understanding of code-switching phenomena is achieved. Linguists continue to debate apparent counter-examples to proposed code-switching theories and constraints. The
Closed-class Constraint, developed by
Aravind Joshi, posits that
closed class items (pronouns, prepositions, conjunctions, etc.) cannot be switched. The
Functional Head Constraint developed by Belazi et al. holds that code-switching cannot occur between a
functional head (a
complementizer, a
determiner, an
inflection, etc.) and its complement (sentence, noun-phrase, verb-phrase). These constraints, among others like the Matrix Language-Frame model, are controversial among linguists positing alternative theories, as they are seen to claim universality and make general predictions based upon specific presumptions about the nature of syntax. == Neuroscience ==