Code Switching in Bilingual Speech: Grammar and Constraints

Introduction

Although it sounds like something straight from a James Bond thriller, the term code switching is actually used to describe cases in which a bilingual speaker speaks to another bilingual with the same linguistic background and shifts from one language to another in the course of conversation (Wei, 2000). Code switching is also employed because it can help convey more meaning than a single language provides, rather than reflecting the speakers' specific preferences for one language over the other (Veronosi, 2000). In an increasingly multicultural world, understanding how people acquire language and apply it in multilingual situations has assumed greater importance than ever, and linguists have contributed to a growing body of research in this area in recent years.

The purpose of this paper is to provide an overview of the grammar of code switching, some constraints associated with the concept, a description of the quantitative and qualitative differences that affect language acquisition and use, and the code-switching differences between children and adults. A critical review of the peer-reviewed and scholarly literature is followed by a summary of the research and salient findings in the conclusion.

Grammar of Code Switching

The occurrence of code switching — the alternation of two languages both between and within sentences — has been demonstrated to be controlled by extra-linguistic (social and situational) as well as intra-linguistic (structural) factors. For instance, Poplack (2000) proposes two grammatical constraints that appear to operate on code switching:

1. The free morpheme constraint, which states that codes may be switched after any constituent in discourse, provided that constituent is not a bound morpheme; and,

2. The equivalence constraint, which holds that code switching tends to occur at points in discourse where the juxtaposition of two languages does not violate a surface syntactic rule of either language (Wei, 2000, p. 216).

According to Bakker (1997), there is a clear typological dimension in code mixing, involving little or no word-internal mixing when two fusional languages are paired, and massive word-internal mixing when one language in the pair is agglutinative. Citing Myers-Scotton's (1993) proposed matrix language frame model to account for this type of code mixing, Bakker (1997) reports that: "Very briefly, this model states that there is one matrix language, in which foreign elements can be employed. That is, the matrix language provides the grammatical framework of the code-mixing utterance. The other language is called the embedded language. If the embedded elements are longer than one word, they should follow the grammatical system of the embedded language" (p. 180). Anything else should follow the grammatical system of the matrix language, including bound and free grammatical morphemes (termed "system morphemes" by Myers-Scotton, 1993). Bakker (1997) suggests that "this works neatly for many language pairs with different typological characteristics" (p. 180).

Subsequent research has identified three types of code switching and code mixing: (a) alternation, (b) insertion, and (c) congruent lexicalization, each associated with different social situations (Bakker, 1997):

1. Alternation. This type of switching occurs when bilinguals begin a sentence in one language and end it in another. Both languages retain their grammatical characteristics.

2. Insertion. In these cases, one language provides the grammatical framework into which elements from another language are placed; the embedded elements are restricted primarily to stems or phrases. Bakker notes that "this type can be associated with most of the language pairs that Myers-Scotton studied (1993)" (p. 180).

3. Congruent lexicalization. This is the most complex of the three types and shows an inextricable mixture of two languages in which one cannot identify a matrix language, and in which the grammatical systems do not remain separate but have considerably converged. According to Bakker (1997), "this type may be rarer than the other two types" (p. 180).

These components form the basis for the grammatical form of code switching: "In the composition of linguistic structures, content morphemes contribute whatever semantic and pragmatic messages the speaker wishes to convey and, in this initiating role, they project directions selecting the system morphemes which are the nuts and bolts — the grammatical system — which give the constituent its form" (Myers-Scotton, 1993, p. 255). There are also important informative clues that emerge during the code-switching process. For example, "code switching signals contextual information equivalent to what in monolingual settings is conveyed through prosody or other syntactic or lexical processes. It generates the presuppositions in terms of which the content of what is said is decoded" (Myers-Scotton, 1995, p. 54). By and large, code switching is an oral function and does not appear to lend itself easily to written form: "Code switching is seen less in prose, and within that framework surfaces very little in scholarly writing. It is used most often in dialogue, many times in forms meant to be representative of linguistic variation or stream-of-consciousness style utterances" (Callahan, 2003, p. 12).

Constraints of Code Switching

Notwithstanding the value of the frameworks described above for understanding what compels bilingual speakers to incorporate components of two or more languages during speech, researchers have also identified a number of constraints that must be taken into account. Three general approaches are apparent in past efforts to conceptualize these constraints:

1. Researchers articulated constraints on switching from the surface — largely using linear ordering, form class, or the size of switched material;

2. Some researchers proposed that constraints were driven by the same principles or rules formulated under current syntactic theories to explain syntactic structures within a single language;

3. Others suggested that a major linguistic constraint on code switching is related to clashes in subcategorization restrictions between the languages involved (Myers-Scotton, 1993).

A number of models have been proposed to resolve the grammatical constraints on intrasentential switching — that is, to determine whether the switch from one language to another tends to follow or violate the grammatical rules of either language (Myers-Scotton, 1993). Poplack (1980) and Sankoff and Poplack (1981) were the first to postulate linguistic constraints operating on intrasentential code switching. They defined two such constraints:

1. The free morpheme constraint predicts that a switch may not occur between a bound morpheme and a lexical form unless the latter has been phonologically integrated into the language of the bound morpheme (i.e., borrowing). For example, the Spanish-English code-switch flipeando is a well-formed Spanish form, whereas run-eando is not, because the phonology of run is unambiguously English and that of -eando is Spanish.

2. The equivalence constraint predicts that the order of sentence constituents immediately adjacent to and on both sides of the switch point must be grammatical with respect to both languages simultaneously.

The equivalence constraint is illustrated in Figure 1 below, where dotted lines indicate permissible switch points and arrows indicate the surface relationships of the two languages; switches can take place at, but not between, the dotted lines:

Figure 1. Equivalence constraint rule in bilingual code switching.
Source: Blanc & Hamers, 2000, p. 262.

The assumption behind the concept of equivalence is that it serves to facilitate the code-switching process. According to Blanc and Hamers, there can also be equivalence of categories (lexical elements, morphosyntactic features, and so forth) as well as of the relations between categories (for example, word order); however, the concept of equivalence is itself problematic. There is no precise match between categories in different languages (Blanc & Hamers, 2000). Furthermore, from a psycholinguistic point of view, a speech community may recognize categories from different languages as equivalent, whereas another community may not (Blanc & Hamers, 2000). In addition, the equivalence constraint assumes that the two switched languages share the same categories and makes no prediction about categorial mismatches: "If switches occur at sites where there is no structural equivalence between the two languages (when, for example, the two languages require a different word order), they sometimes involve omission or repetition of constituents" (Blanc & Hamers, 2000, p. 262).

Conclusion

Although the Human Genome Project has mapped the human DNA sequence in its entirety, much still remains unknown or unclear about how the brain functions in acquiring and processing speech. There has been an increasing amount of attention paid to these processes in recent years, providing researchers with new insights and directions for future studies. To date, the research shows that code switching is used to describe instances in which a bilingual speaker speaks to another bilingual with the same linguistic background and shifts from one language to another during the course of conversation (Wei, 2000). Code switching has been shown to be employed not only because of speakers' specific preferences for one language over the other, but also because it can help convey more meaning than a single language provides (Veronosi, 2000).

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