In introducing this special issue of Bilingualism: Language and Cognition, we feel it is critical to clarify what we understand ‘linguistic convergence’ to mean in the context of bilingualism, since ‘convergence’ is a technical term more readily associated with the field of language contact than with the field of bilingualism (for recent discussions of the role of convergence in contact see Thomason and Kaufman, 1988; Thomason, 2001; Myers-Scotton, 2002; Clyne, 2003; Winford, 2003). Within the language contact literature, the term invites a variety of uses. Some researchers adopt a definition of convergence that requires that all languages in a contact situation change, sometimes to the extent that the source of a given linguistic feature cannot be determined (see April McMahon's commentary in this issue). For others, convergence may be more broadly defined to also apply to situations in which one language has undergone structural incursions of various sorts from contact with another.

Most work investigating the role of convergence in situations of language attrition has focused on the morpho-syntactic restructuring of the dying language variety. A central concern of such research has been untangling the factors driving the restructuring with an eye towards establishing whether the changes observed are best viewed as externally driven or, by contrast, as internally motivated. A second and equally important concern of this research attempts to define the domains of the linguistic system that may be the most permeable to external influence. The present study provides a contribution to this line of research and sheds light on its two leading concerns from the domain of phonology and phonetics. Specifically, we present the results of an instrumental study of the phonological vowel system of Frenchville French and argue that this linguistic variety is undergoing a perceptually striking process of phonetic convergence with English that is motivated by the auditory and acoustic similarity between a subset of vowels in the contact languages. An interesting consequence of our analysis is that bilingual phonologies may become particularly permeable to inter-linguistic influence precisely where they are acoustically and perceptually unstable, and where they are already congruent to some degree.

Bullock and Gerfen show that two of the last speakers of French in Frenchville, Pennsylvania, systematically replace the French front mid round vowel (in words like deux, neuf) with the rhoticized schwa of American English, their dominant language. As the authors argue, it is unlikely that this sound change would have arisen in the speech of French speakers who were not bilingual in English.

In this paper we present experimental evidence showing that Buenos Aires Spanish differs from other Spanish varieties in the realization of pre-nuclear pitch accents and in the final fall in broad focus declarative utterances. Whereas other Spanish varieties have been described consistently as showing late peak alignments, Buenos Aires Spanish displays early peak alignments. The alignment pattern found in Buenos Aires broad focus declarative utterances is not totally foreign to Spanish: it is attested in a quite different function, i.e. to signal contrastive focus. In addition, Buenos Aires Spanish also seems to differ from other Spanish varieties in the realization of the intonation contour in utterance-final intonational phrases, where a pronounced tendency for down-stepped peaks is observed. We argue that these patterns, which emerged at the turn of the twentieth century, and coincided with the peak of Italian immigration, are due to a combination of direct and indirect transfer from Italian. As a result, two intonational systems that were typologically similar before contact took place (Hualde, 2002) became more similar after contact, in what can be interpreted as a case of convergence.

Using evidence from first-hand experimental work and existing studies, Colantoni and Gurlekian take a tentative but encouraging step towards exploring the role of contact in explaining intonational change. Their central question is whether Buenos Aires Spanish intonation is distinctive relative to other varieties of Spanish; and if so, whether that distinctiveness is due to contact with Italian.

Many simultaneous bilinguals exhibit loss or incomplete acquisition of their heritage language under conditions of exposure and use of the majority language (Silva-Corvalán, 1994, 2003; Polinsky, 1997; Toribio, 2001; Montrul, 2002). Recent work within discourse-functional (Silva-Corvalán 1994) and generative perspectives (Sorace, 2000; Montrul; 2002; Tsimpli, Sorace, Heycock, Filaci and Bouba, 2003, in press) suggests that while syntax proper is impervious to language loss or attrition, syntax-related interfaces like lexical-semantics and discourse-pragmatics are not. This study investigates argument expression in adult simultaneous bilinguals who are heritage speakers of Spanish, because in this language subjects, direct, and indirect objects are regulated by syntactic, pragmatic and semantic factors. It was hypothesized that if language loss affects interface areas of competence more than the purely syntactic domains, then Spanish heritage speakers should display robust knowledge of null subjects as well as object clitics, but variable behavior in the pragmatic distribution of null vs. overt subjects, the a preposition with animate direct objects, and cases of semantically based dative clitic-doubling. Results of an oral production task administered to 24 intermediate and advanced heritage speakers and 20 monolinguals confirmed the hypotheses. With the erosion of pragmatic and semantic features, the grammars of the intermediate proficiency Spanish heritage speakers appear to display morphosyntactic convergence with English in the expression of subject and object arguments.

Montrul's study is an important contribution to a recently emerged research approach to the study of bilingualism and languages in contact, characterized by its sound theoretical basis and its reliance on data from different – and traditionally non-integrated – domains of language development: bilingual first language acquisition (Müller and Hulk, 2001; Paradis and Navarro, 2003; Serratrice, 2004; Serratrice, Sorace and Paoli, in press), adult second language acquisition (Filiaci, 2003; Sorace, 2003), and native language attrition (Gurel, 2002; Tsimpli, Sorace, Heycock and Filiaci, in press). The generalization that is emerging from this approach is that interfaces between syntax and other cognitive systems (i.e. discourse pragmatics, lexical-semantics) exhibit more developmental instability than narrow syntax. For L1 attrition, which is the specific focus of the paper, this means that aspects of grammar at the syntax–discourse interface are more vulnerable to attrition than purely syntactic aspects. The identification of restrictions on the domain of occurrence of attrition is consistent with much previous descriptive research on this topic (e.g. Seliger and Vago, 1991). More recently, the same conclusion has been reached by a study on individual language attrition by Tsimpli et al. (in press), who investigated knowledge of the referential pronominal system in Greek and Italian in very advanced speakers of English. In this paper, Montrul tests the generalization on second-generation speakers of Spanish – or “heritage speakers” – a bilingual group that presents different characteristics from the adult L2 speakers investigated in Tsimpli et al.'s study. In addition to referential subjects, she also focuses on a different interface area of grammar – direct objects – that had not been investigated before. In these respects, Montrul's study is a welcome development. In other respects, however, the data are less than convincing and do not allow a straightforward interpretation. My commentary focuses on three fundamental questions raised not only by this study, but also by this type of research in general. The main focus will be the expression of referential subjects since this aspect of grammar has been investigated in other studies and therefore offers the possibility of direct comparison among results.

In this paper, I present an exploratory study on cross-linguistic interference among Quechua-Spanish bilingual children living in a language contact situation. The study focuses on convergence in the tense, aspectual and evidentiality systems of the two languages. While in Quechua past tense features are strongly linked to evidentiality in the matrix of features associated with the functional category Tense, in Spanish, past tense features are linked to aspectual features. The study presents evidence that supports the Functional Convergence Hypothesis according to which syntactic convergence among bilingual speakers is favored when the matrix of features associated with a functional category is partially divergent, as is the case for Tense in Spanish and Quechua. The Spanish results indicate that among bilinguals past tense is associated with evidentiality features and contrast sharply with the results of the monolingual comparison group. Bilingual Quechua results exhibit an incipient emergence of discourse-oriented background and foreground distinctions, similar to those found in Spanish in association with aspectual morphology.

Liliana Sánchez' paper is a welcome contribution to the growing body of literature on Andean Spanish (cf. a recent survey in Muysken, 2004a), welcome both because a well-motivated and clearly described methodology is used and because it is embedded in an explicit theoretical framework. I do not have reservations about the overall conclusions of the study, but would like to draw attention to three issues: grammatical encoding versus pragmatic inference, the completeness of the analysis, and the issue of form learning versus meaning construction.

The present article examines one property of bilingual speech – convergence – and strives towards explanatory depth by attending to the insights of the antecedent research in formal linguistics, psycholinguistics, and sociolinguistics. In particular, the paper adopts as a point of departure (and further substantiates) the argument that convergence will be evidenced in the syntax–pragmatic interface (Hulk and Müller, 2000) and the assertion that convergence is a ‘bilingual optimization strategy’ (Muysken, 2002), in advancing the claim that convergence (cum congruent lexicalization) in bilingual speech may be amplified or attenuated in tandem with the language mode (bilingual versus monolingual) of the bilingual (Grosjean, 1998). Specifically, it will be demonstrated through an analysis of two individual bilinguals' productions in both monolingual and bilingual modes that the convergence that is already manifested to some degree in these individuals' Spanish is enhanced in Spanish-English code-switching when their languages are simultaneously activated and deployed.

In an important theoretical contribution to our understanding of language contact, Toribio elaborates on the familiar generalization, best known from the work of Silva-Corvalán, that contact varieties resemble monolingual lects of the same language in overall grammar, but differ with regard to (a) the selection of structures and (b) the semantic-pragmatic constraints on the use of structures. In Toribio's valuable elaboration of this basic idea, these peculiar patterns of selection and constraint in the contact variety are not the same in all contexts of use, but differ depending on whether the bilingual is in the single-language mode, or in the codeswitching mode where stretches of speech in the contact variety alternate, rapidly and relatively seamlessly, with stretches in the acrolect. The insight is that the same type of process that distinguishes the contact variety from its monolingual reference lects also distinguishes, within the contact variety, the codeswitching mode from its single-language reference mode.

This issue of Bilingualism: Language and Cognition is about convergence, a type of language change that is contact-induced and results in greater similarity between two languages that are in contact with each other. In Backus (forthcoming), I have attempted an overview of contact-induced language change, focusing on causal factors, on mechanisms of change, and on the actual changes. In this conclusion, I will try to give convergence its rightful place in this general typology, referencing the contributions to this volume where appropriate.