Short Summaries of the Uniform Structure Principle, the MLF Model and the 4-M Model

The Uniform Structure Principle (USP)

• Although the USP is introduced only in Myers-Scotton, 2002 (Contact Linguistics), it is obvious that it offers an explanation for the distributions of morpheme types in many types of bilingual speech discussed in earlier works (including classic CS under the MLF model).
• Even though the USP clearly operates in monolingual linguistic data (i.e., uniform structure is maintained in a given constituent type), how uniform structure applies in bilingual data is not so obvious. Thus, there is a need to recognize the USP when dealing with bilingual data:
• Here is the USP: A given constituent type in any language has a uniform structure and requirements of well-formedness for this constituent type must be observed whenever that constituent appears. In bilingual speech, the structures of the Matrix Language (ML) are always preferred; that is, following the ML's structures satisfies the Uniform Structure Principle.

Embedded Language (EL) islands, phrases from other varieties participating in the clause, are allowed if they meet EL well-formedness conditions, but also ML conditions applying to the clause as a whole (e.g. phrase placement).

See curriculum vitae for information about Myers-Scotton, 2002; 2005c for evidence that the USP applies in classic CS.

The Matrix Language Frame (MLF) Model Summarized

• The key word characterizing the MLF model is asymmetry.
• Asymmetry is obvious in (a) the roles of the participating varieties (languages) and (b) in differences in distribution of morpheme types.
• One participating language dominates in the sense that it supplies the morpho-syntactic frame for the bilingual clause. This language is identified as the Matrix Language (ML). The ML is identified by the empirical support for the Morpheme Order Principle and the System Morpheme Principle (see below).
• Having only one language supplying the frame for the bilingual clause is the feature that differentiates classic CS from composite CS.
• The MLF model only applies unconditionally to classic CS.
• In composite CS, more than one language can contribute abstract structure that affects the surface structure of the morpho-syntactic frame. (See Myers-Scotton, 2002 for some details.)
• Asymmetry also differentiates morpheme types under the MLF model as either content morphemes or system morphemes.
• In classic CS (under the MLF model), the role of the non-ML, which is called the Embedded Language (EL), largely is limited to supplying content morphemes in mixed constituents, or EL phrase-level constituents (called EL islands), or both.
• (Note: In some data sets, early system morphemes or even an occasional bridge system morpheme do come from the EL, but these are not counter-examples to any provisions of the model.)
• Content morphemes are defined as assigning or receiving thematic roles; for example, nouns receive such roles and most verbs assign them.
• System morphemes do not assign or receive thematic roles. Under the 4-M model system morphemes are further divided into three types.
• The MLF model contains two principles that operate as hypotheses about the participation of the different languages involved in CS:
• The Morpheme Order Principle states that morpheme order within the bilingual clause comes from only one language and this language is identified as the ML.
• (Note that within EL islands, which may occur in the bilingual clause, EL morpheme order is present.)
• The System Morpheme Principle states that one type of system morpheme must come from only one of the participating language and this language is identified as the ML.
• Note that the newer 4-M model names this type of morpheme as an outsider late system morpheme .

The 4-M Model Summarized

• The 4-M model is not a revision of the MLF model—even though its features help explain why the MLF model is supported. Instead, the 4-M model is a model of morpheme classification that should apply to language in general (cf. Myers-Scotton & Jake, 2000; Myers-Scotton, 2002; Myers-Scotton and Jake forthcoming).
• Under the 4-M model, morphemes are classified in terms of their empirically-evident syntactic roles, as well as hypotheses about how they are activated in language production.
• There are four types of morphemes: content morphemes, and three types of system morphemes: early SMs and two types of late SMs, bridges and outsiders.
• As in the MLF model, content morphemes assign and receive thematic roles; in this feature, they continue to differ from all system morphemes.
• But the 4-M model emphasizes a further division: Content morphemes and early SMs group together as conceptually-activated, as opposed to late system morphemes, which are structurally-assigned.
• Conceptually-activated means that speaker pre-linguistic intentions activate the language-specific semantic-pragmatic feature bundles that become lemmas in the mental lexicon. (Lemmas are abstract features that underlie surface level morphemes.) In this sense, content morphemes are "directly elected" and early SMs that may accompany them on the surface are "indirectly elected" (cf. Levelt, 1989 and Bock and Levelt, 1994). See Myers-Scotton, 2002 for details.
• Structurally-assigned means that late SMs are not salient until the level of the formulator (in language production). It is at this level that larger phrases and clauses are assembled; late SMs do this work. See Myers-Scotton, 2002 for details.
• What do early SMs do? They occur with content morphemes (their heads) and they flesh out the meaning of their heads. Examples: plural affixes, determiners.
• In CS corpora, most early SMs come from the ML, but note that the System Morpheme Priciple does not apply to early SMs or bridge SMs; it only specifies that outsiders must come from the ML.
• How do bridges differ from outsiders?
• Bridges are, in effect, "bridges" between elements that make up larger constituents. Bridges depend on their form from information within the maximal projection in which they occur; that is, they occur to satisfy well-formedness conditions within that projection. Examples include elements that join together two NPs, with an associative, equivalent or partitive meaning (e.g. "of" in English in bone of Bora or Bora's bone . Most bridges come from the ML in CS.
• Outsiders depend on information outsider the elements with which they occur; this information can come from an element in another constituent in the clause, or from the discourse. Outsiders are the primary way that argument structure is indicated and agreement relations are maintained in any clause . Examples of outsiders: morphemes marking subject or object-verb agreement; case affixes in some languages.
• Observations of how different types of morpheme have different distributions in actual surface level constructions give rise to The Differential Access Hypothesis . This hypothesis suggests that the different types of morphemes under the 4-M model are differentially accessed in the abstract levels of the production process. Content morphemes and early SMs are salient at the level of the mental lexicon, but late SMs do not become salient under the level of the formulator (cf. Myers-Scotton, 2002:78; Myers-Scotton, 2005b).
• This hypothesis is an attempt to explain differences in distributions of morpheme types. Data from codeswitching, but also other language phenomena, support the hypothesis.