User:LaShubbySheeks/sandbox

Constraint-based model: Poplack (1980)
Shana Poplack's model of code-switching is an influential theory of the grammar of code-switching. In this model, code-switching is subject to two constraints. The free-morpheme constraint stipulates that code-switching cannot occur between a lexical stem and bound morphemes. Essentially, this constraint distinguishes code-switching from borrowing. Generally, borrowing occurs in the lexicon, while code-switching occurs at either the syntax level or the utterance-construction level. The equivalence constraint predicts that switches occur only at points where the surface structures of the languages coincide, or between sentence elements that are normally ordered in the same way by each individual grammar. For example, the sentence: "I like you porque eres simpático" ("I like you because you are friendly") is allowed because it obeys the syntactic rules of both Spanish and English. 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.

Moreover, some observations on Sankoff and Poplack's model were later pointed out by outside researchers. The observations regard the free-morpheme and equivalence constraints that are insufficiently restrictive, meaning there are numerous exceptions that occur. For example, the free morpheme constraint does not account for why switching is impossible between certain free morphemes. The sentence: "The students had visto la película italiana" ("The students had seen the Italian movie") does not occur in Spanish-English code-switching, yet the free-morpheme constraint would seem to posit that it can. 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. Sankoff and Poplack's model focuses on the instances where code-switching does not interfere with the syntactic rule of the speaker's primary or second language. 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.