Nancy Mae Antrim
email: nantrim@sulross.edu

Sul Ross

A survey of SLA doctoral programs in Canada and the USA

The increasing interest in second language acquisition (SLA) has sharpened the focus on SLA research. While most university linguistic programs and departments offer at least a course in SLA, not all offer the opportunity to concentrate on SLA research. This article provides an overview of the programs/departments offering opportunities for SLA research. These programs range from ones offering a PhD. in Second Language Acquisition to those which provide a strong research basis while concentrating primarily on teaching. The programs are reviewed with respect to their key features as well as pertinent student centred information.

I Introduction

The European Union is considering a common language; English has become a global language; endangered languages are being taught as second languages in an attempt to revive them. In the USA, along with the recent political response to bilingual education and the increasing militancy of English Only movements, there has been a renewed interest in second language acquisition (SLA). While considerable focus has been placed on the field of second language (L2) learning and teaching with the development of new or revised certification programs and changes in public school programs, there has also been a resulting increased awareness of the need for research into second language acquisition. This increased interest in language learning raises the question of where a prospective student could pursue a doctoral program in SLA. What programs are currently available to provide graduate training in the foundations for SLA research? Second language acquisition by its very nature is a highly interdisciplinary field having its own research agenda while closely tied with linguistics, psychology, anthropology and education. This field of inquiry can be divided into two branches, those same two branches that traditionally have been applied to the field of linguistics in general: theoretical and applied.

Theoretical research focuses on the general principles and processes that comprise an individual's knowledge of a second language, while applied research is concerned with the learning and teaching of second languages. Second language acquisition research, whether theoretical or applied, contributes to our understanding of cognition, as well as language and the relationships between language, society, culture and the individual. However, there appears to be a lack of consensus as to where SLA belongs. Clearly second language learning and teaching is an area under applied linguistics and would be found in an applied program or department, or within a school of education. However, SLA research has implications for second language teaching that may be more apparent than other so-called theoretical areas. While this survey of graduate education in SLA is not an exposition on the place of the discipline in linguistics, it is interesting to note that several institutions draw a strict line between theoretical and applied fields, locating SLA in applied. They advise prospective students interested in SLA to see programs under applied linguistics or education/TESOL.

In the USA and Canada -the geographical area covered in this survey -institutions that offer training at the doctoral level in SLA can be roughly divided into four main categories. There are programs that are strongly focused on SLA research and, in fact, offer a PhD in SLA; ones that offer PhDs in Linguistics with an SLA focus or concentration; ones that provide a theoretical foundation but emphasize second language teaching methodology rather than theoretical research; and, finally, ones that focus on TESOL but do include some theory. Programs whose concern is narrowly with second language learning and teaching are not considered in this survey.

In evaluating graduate education in SLA there are several factors that should be considered. First, and I feel foremost, there is the degree to which the program draws upon faculty and resources outside of the department that houses the program. It may be difficult for a single department to encompass the range of expertise inherent to a truly interdisciplinary field, unless it specifically identified itself as a department of second language acquisition, of which there are several. Another factor that is important to consider is the number of faculty involved, because a program with a small faculty limits students' exposure to different approaches, theoretical orientations, and research areas. In addition, one would ideally want a program with a strong theoretical foundation, since original research in the acquisition of second language (L2) phonology, syntax, semantics, or language use requires depth of training in phonology, syntax, semantics, and sociolinguistics.

Moreover, while a student may not need access to language learners of the languages he or she is interested in researching, having that resource available would be advantageous in the absence of funding for fieldwork away from the university. Finally, location becomes an important consideration from two perspectives: first because of access to second language learners and, secondly, because of access to faculty and facilities at neighbouring institutions.

In selecting programs to consider for this article, several guides and directories on graduate programs were consulted to determine the schools offering graduate degrees in linguistics and/or second language acquisition. 1 After compiling a list of these programs, each program was checked to see if the program offered a doctorate. Programs offering only master's degrees were not considered. After narrowing down the field to only those schools offering doctoral degrees, each school's website was consulted to determine whether the program had second language acquisition as a possible focus. This left 31 programs to be considered.

Appendices 1 and 2 summarize key features of 31 American and Canadian doctoral programs offering a concentration in SLA. In addition to these 31 programs, there are several (not listed in the appendices) that have a strong first language acquisition focus as well as faculty interested in SLA. Among them is the City University of New 1 There are a number of guides and directories available including Peterson's Graduate Schools in the US, Princeton Review's Complete Guide of Graduate Programs in the Arts and Sciences, and the Independent Publishing Group's Directory of Graduate Programs in Arts and Humanities. These are updated yearly. There is also a website GradSchools.com that lists programs and schools. Finally, the Linguist List (http://linguistlist.org) maintains a list of linguistics programs.

York (CUNY). With respect to SLA, CUNY's stated interest is in language teaching, but the university has a number of faculty working on first language acquisition and several who list SLA as a research interest. The University of Minnesota is also primarily focused on first language acquisition, but has faculty who work on SLA, as well as language teaching. Their resources include the Center for Advanced Research on Language Acquisition (CARLA), which currently is focused on research related to second language teaching, learning, and assessment. In addition, there are several schools where SLA is not a major research area but which offer a strong theoretical foundation and have at least one faculty member with SLA as a research interest. Notable schools in this category include Rutgers, the University of California at San Diego, Harvard, Purdue, and the University of Southern California. All have strong linguistics programs.

No survey of linguistics programs would be complete without mention of Massachusetts Institute of Technology. MIT's 16-member department has had a phenomenal impact on the way we view linguistics today. Focused on generative grammar, the department's primary research involves the development of formal models of language. Their program includes the traditional core areas of theoretical linguistics, notably phonology, morphology, syntax, and semantics. They also offer an interdisciplinary psycholinguistics track with the Department of Brain and Cognitive Sciences. In addition to providing a strong theoretical foundation, MIT has two faculty members working on second language acquisition.

The information presented in Appendices 1 and 2 was culled from on-line sources. It is therefore limited by the accuracy and currency of program-sponsored websites. Websites vary in the information they provide, their manner of organization, and in how up-to-date they are kept. A few of the 31 programs are discussed individually below, either because they are representative of their classification or because of some noteworthy feature. In particular, programs offering PhDs in SLA are discussed in greatest detail. In an effort to ensure the currency and accuracy of each of the individual programs discussed, each program discussed below was contacted via email. Follow-up emails were sent to those programs not replying to the initial request.

II Programs offering a PhD in second language acquisition

Among programs with a strong emphasis on SLA research are several that offer PhDs in SLA rather than in Linguistics in general. These include Carnegie Mellon, the University of Hawaii, the University of Iowa and the University of Arizona. Michigan State University has announced a new doctoral program in Second Language Studies that includes an SLA tract. While these programs address SLA research, they all have a strong L2 teaching component.

The PhD Program in SLA at Carnegie Mellon is based in the Department of Modern Languages. It has a strong interdisciplinary orientation, drawing on faculty from Modern Languages, Psychology, English and Philosophy. The 33 faculty members currently involved in the program represent seven languages in addition to English: German, Spanish, French, Italian, Russian, Chinese and Japanese. Students at Carnegie Mellon also have access to the faculty and resources at the University of Pittsburgh. Research initiatives at Carnegie Mellon focus on two major areas: second language literacy and contexts of learning. The former addresses cross-linguistic variation in lexical processing, the development of kanji among learners of Japanese, teacher feedback to L2 writing and the analysis of Japanese scientific research genres in academic settings. Current research at Carnegie Mellon in classroombased learning in different contexts includes oral and written fluency in French, reading processes in Japanese and acquisition of Japanese and Spanish in elementary schools.

Applicants are expected to bring to the program a level of proficiency sufficient for research in a language other than English. A unique requirement at Carnegie Mellon is that every student in the program teaches one language course per semester.

The University of Hawaii's PhD in SLA is offered through the Department of Second Language Studies. Previously this was a department of English as a Second Language, but the name was changed in 2000 to reflect the department's boarder focus. The department itself has 14 full-time faculty whose specializations directly involve second language acquisition. In addition to the departmental faculty, the 28 member graduate program's faculty include specialists from Anthropology, East Asian Languages, Hawaiian and Indo-Pacific Languages, Linguistics, Educational Psychology, Teacher Education, and Curriculum Studies. The program offers four areas of specialization: second language analysis, second language learning, second language use and second language pedagogy. While the PhD program is focused on research, they also offer an MA in ESL, which focuses on teaching. In addition to these graduate degrees, the department administers an Advanced Graduate Certificate in Second Language Studies, which is aimed at those who have an MA or PhD or those who are working on post-graduate degrees in related fields. There are externally funded centres associated with the department that help provide financial support for graduate students. These include: the National Foreign Language Resource Center, the Center for Second Language Research and the Center for Advanced Language Study.

The University of Iowa also offers a PhD in SLA, an interdisciplinary degree under the aegis of FLARE (Foreign Language Acquisition Research and Education). Students take courses depending on their interests from the departments of Asian Languages, Curriculum and Instruction, French and Italian, German, Linguistics, Psychological and Quantitative Foundations, Rhetoric, Spanish and Portuguese, and Speech Pathology and Audiology. Of the over 20 associated faculty members connected with FLARE, nine of them are in linguistics. There are also linguists in the departments of French, Spanish and Portuguese and East Asian languages working on SLA. The program building on a theoretical core of phonology and syntax offers three areas of specialization: SLA-linguistics, SLA-programmatic (designed for students interested in language program direction) and SLA-technology.

The University of Arizona offers a PhD in Second Language Acquisition and Teaching (SLAT). This is a large interdisciplinary program of over 60 faculty members with appointments in 15 departments from the College of Humanities, the College of Science, the College of Social and Behavioral Science, and the College of Education. The departments involved include Anthropology, Classics, East Asian Studies, English, French and Italian, German Studies, Linguistics, Near Eastern Studies, Psychology, Russian and Slavic Languages, Spanish and Portuguese, Special Education and Rehabilitation, Speech and Hearing Sciences, Teaching and Teacher Education, and Language, Reading and Culture. There are four areas of specialization: L2 analysis focuses on phonology, morphology and syntax and the development of theory and the formal analysis of SLA; L2 use and discourse analysis addresses socio-cultural factors and includes language variation and language planning; L2 processes and learning deals with the cognitive, linguistic and social process of SLA; and L2 pedagogical theory and program administration is the fourth area of specialization. The University of Arizona also publishes the Arizona Working Papers in SLA and Teaching. The criteria for admission includes evidence of successful prior experience in language teaching.

The newest doctoral program under this heading is a PhD in Second Language Studies (SLS) offered by Michigan State University. This new PhD program in SLS has two possible tracts: (1) SLA and (2) SLA and Language Teaching. They have a core faculty of eight with 23 affiliated faculty from the Departments of Communication, Psychology, Spanish and Portuguese, English, Counseling, Educational Psychology and Special Education, as well as Linguistics and Germanic, Slavic, Asian and African Languages. For the SLS program, a proficiency in the language of specialization is required. For the second tract in SLA and Language Teaching preference is given to prior second/foreign language teaching experience. This new program is admitting students from Fall 2005 onwards.

Michigan State University continues to offer a PhD in linguistics from their Department of Linguistics and Germanic, Slavic, Asian and African Languages. Among the languages studied are Amharic, Arabic, Hebrew, Chinese, Japanese, German, Hausa, Kiswahili, Vietnamese, Korean, Tagalog, Hindi, Kazakh and Russian. There are 24 members of the department with an additional 10-12 affiliated faculty. Their program focuses on SLA, theoretical linguistics, cognitive science, literary studies, cultural studies and language pedagogy. They also offer an MA in TESOL. Student research is supported by the Center for the Enhancement of Linguistic Student Research.

III Programs offering PhDs in Linguistics with an SLA focus/concentration

While many of the programs that train students in the field of SLA include pedagogy, some programs either exclude pedagogy or offer language teaching as a separate area of study within a different department.

Four such schools in the USA are Boston University, Indiana University, the University of Illinois at Urbana-Champaign and the University of Washington, while in Canada McGill University and the University of Toronto would fall within this category.

Indiana University has one of the oldest linguistics programs in the USA, granting degrees since around 1948, and becoming established as a department in 1960. The department has 14 faculty members with adjunct faculty in the Departments of Speech and Hearing, Psychology, Mathematics, Spanish, East Asian Languages, French, Germanic Studies and Slavic Languages. In addition to SLA, the department's strengths include African linguistics, computational linguistics, phonetics, phonology, cognitive science, semantics, syntax, applied and field linguistics. There is an additional program in TESOL (Teaching English to Speakers of Other Languages) and applied linguistics. The curriculum at Indiana University provides a broad foundation in linguistic theory, requiring graduate students regardless of specialization to take a course in language acquisition. Currently most of the SLA research is being carried out by the Program in TESOL and Applied Linguistics.

The Department of Linguistics at McGill University in Montreal offers a PhD in Linguistics. Specialization in generative SLA is possible both at the course level and for thesis supervision. In addition, the department is involved with a cross-disciplinary language acquisition program. There are 12 faculty members involved in the Language Acquisition Program. These include faculty from linguistics, psychology, education, and communication sciences and disorders. Faculty members currently are working within the following language families: Amerindian, Austronesian, Celtic, Chukotko-Kamchatkan, East Asian, Germanic, Romance and Slavic. McGill specifically indicates that it does not offer training or supervision in language teaching. Prospective students interested in Applied Linguistics or TESL are referred to the school of education.

The University of Illinois at Urbana-Champaign offers a PhD in Linguistics with six possible sub-specializations: computational linguistics, historical linguistics, phonology/phonetics, psycholinguistics/ neurolinguistics, sociolinguistics and syntax. Although SLA is not specifically mentioned as a sub-specialization, it is subsumed within psycholinguistics/neurolinguistics. There is the additional opportunity to work in second language acquisition through the university's Second Language Acquisition and Teacher Education program (SLATE). SLATE is a multidisciplinary, nondegree granting body with faculty from both the College of Education and the College of Liberal Arts and Sciences including five faculty members from Linguistics. Other scholars involved in SLATE are in the departments of East Asian Languages and Culture, French, Germanic Languages and Literature, Slavic Languages and Literature, and Spanish, Italian and Portuguese. Students receive a doctorate from their home Department but can earn a Certificate of Advanced Study in Second Language Acquisition and Teacher Education. In addition to sponsoring departmental course work, SLATE invites well-known guest lectures in the field to come to campus.

The University of Illinois at Urbana-Champaign also offers an excellent opportunity to work with less commonly taught languages. Currently the department supports classes in the African languages of Bamana, Lingala, Swahili, Kiswahili, Wolof and Zulu. This is in addition to the Department's offerings in Arabic, Hebrew, Hindi and Sanskrit.

The remainder of the programs offering an SLA focus/concentration include language teaching pedagogy in their programs, including four Canadian schools: Simon Fraser University, the University of Ottawa, the l'Université du Québec à Montéal (UQAM) and the University of Victoria.

The University of California at Los Angeles (UCLA) has an interdepartmental program in Applied Linguistics, which includes SLA, discourse and language teaching. Their strong theoretical orientation with an emphasis on field methods, as well as, African and American Indian languages is supported by 29 faculty members. Four faculty have regular appointments in Applied Linguistics/TESL while the remainder are drawn from Anthropology, East Asian Languages and Cultures, Education, Linguistics, Neuroanatomy, Psychology, and Sociology, among others. There are also a number of faculty holding joint appointments with Linguistics and Applied Linguistics/TESL. While the program is administered by the Department of Applied Linguistics and TESL, its focus is on preparing students for research rather than training language teachers. Language acquisition courses are offered under Linguistics, Education and Psychology as well as Applied Linguistics/TESL. Students have access to several language labs including the phonetics lab, the psycholinguistics/neurolinguistics lab and the computational linguistics lab. The department houses the Forum for Language Acquisition Exchange (FLARE), which is a student-run group providing discussions and presentations. This group promotes networking between the students and faculty interested in SLA, as well as, supporting conferences for graduate students.

The University of Georgia has an interdisciplinary program that is drawn from nine departments in the College of Arts and Sciences and three departments in the College of Education. There are separate PhD degrees in TESOL and Foreign Language Education offered through the Department of Language Education in the College of Education. They cite four specializations in applied areas, which include historical linguistics, cognitive linguistics, language variation and SLA. They are particularly interested in training college-level language teachers, although the focus of the SLA concentration is declared to be on linguistic theories and practices. The SLA specialization requires coursework done in French, Spanish, German or in an African or Asian language offered at the University of Georgia. English may also be used to satisfy the language coursework requirement. In addition to the 31 faculty members involved in the program, there are several language labs available. The University of Georgia also houses the Linguistics Atlas Projects, which contain one of the largest collections of linguistic data in the USA.

The Department of Linguistics at the University of Pittsburgh has as its strengths Native American languages, Descriptive linguistics, Hispanic linguistics and applied linguistics. The applied area has a TESOL orientation. Faculty teaching SLA courses have a background in educational psychology and/or theoretical linguistics as well as language teaching experience. Resources include the English Language Institute and the Less-Commonly-Taught Languages Center, which offers courses in languages such as Swahili, Arabic, Irish and Quechua. The department's Language Processing and Acquisition Lab is currently researching the acquisition of English or Hebrew by Russian immigrants. In addition to 10 faculty members in linguistics and nine affiliated professors, students at the University of Pittsburgh have access to the faculty and resources at Carnegie Mellon.

The Departments of Linguistics at both the University of Oregon and Rice University focus on language description and functionalist approaches to grammar. The University of Oregon offers three areas of specialization. These are descriptive linguistics and fieldwork, language and cognition and second language acquisition. Research has involved Native American languages, Tibeto-Burman, Austronesian and Slavic languages, as well as languages of Southeast Asia, South Asia and Africa. There are eight faculty members who are currently pursuing six SLA research projects. While SLA is not one of Rice University's primary foci, three of the 15 faculty members include SLA (along with applied linguistics) as an additional research area. Their primary areas involve cognitive linguistics, usage-based approach to grammar, and field linguistics on the languages of North and South America, Austronesia, Australia, Africa, Europe and East Asia, typology, phonetics and phonology, discourse analysis, sociolinguistics, language change, and language and the mind.

Simon Fraser University's Department of Linguistics offers seven major research areas. Their applied linguistics specialization is directed towards research into language learning and teaching. Both courses and research focus on second language acquisition, second language pedagogy, applied phonetics, quantitative research methods as well as computer assisted language leaning. In addition to applied linguistics, students at Simon Fraser may specialize in computational linguistics and cognitive science, discourse analysis and pragmatics, First Nations languages, morphology, phonetics and phonology, and syntax and semantics. The program provides a good theoretical foundation for work in SLA research. Six of the 18 faculty members work within the applied linguistics specialization. With their current staff, the department is not admitting students interested in specializing in first language acquisition or sociolinguistics.

IV SLA programs with a primary concentration on teaching

Although Pennsylvania State University, and the University of Michigan in the USA and l'Université Laval and the University of Toronto/Ontario Institute for studies in Education (OISE) in Canada have their primary SLA emphasis on language teaching, they do also offer opportunities for SLA research. The Department of Languages, Linguistics and Translation at l'Université Laval offers concentrations in theoretical and descriptive linguistics, language and society, translation, and language teaching methodology (didactique des langues). The language teaching concentration includes both theoretical and applied aspects of SLA, focusing on the acquisition of French and English. Their work in SLA draws on several perspectives: generative grammar, sociocultural, and psycholinguistic. Their faculty of 37 includes eight in SLA.

The University of Toronto's department of Linguistics offers a theoretical foundation in linguistics and has several faculty members working on SLA. What is unique about Toronto is the merger between the OISE and the faculty of the University of Toronto (UT) in 1966. OISE/UT offers a number of graduate degrees including a PhD in Second Language Education. Studies in Second Language Education (SLE), offered under the Department of Curriculum, Teaching and Learning at OISE/UT, focuses on curriculum, instruction, learning and policies for education in second or foreign languages. The program is linked with the resources and research of the Modern Language Center from which it draws most of its faculty. While primarily concerned with teaching, the program allows students to take course work in a limited number of departments at the University of Toronto including linguistics. It would be possible to design a program drawing on UT's theoretical foundation and OISE's second language focus. Admission is to OISE/UT and requires an MA thesis or strong research paper as well as two years professional experience.

V Student information

Appendix 2 summarizes admissions requirements and funding sources for each of the 31 programs. While all programs would prefer students to have a background in linguistics, most will accept students with degrees in other fields. A notable exception to this is Simon Fraser in regards to their applied concentration. Simon Fraser will only admit students for the applied linguistics concentration if they have a strong background in general linguistics. In other departments, entering students who lack a strong foundation in linguistics are required to take a number of entry-level courses to provide them with sufficient background. Several programs require a Master's degree. Those schools that allow students into their programs with a Bachelor's degree usually award a Master's upon completion of required coursework, even though most do not accept students into their programs who seek a terminal Master's degree. The MA is seen as one step on the way to a PhD, not an end in itself. Programs requiring an MA as a prerequisite ask for a thesis as evidence of research ability. Programs not requiring an MA ask for a writing sample, an article in linguistics if possible.

All PhD programs surveyed here require a knowledge/proficiency in at least one language other than English. The University of Florida, the University of Iowa, Carnegie-Mellon, and Michigan State University (for track 2: SLA and Language Teaching) require that language proficiency be established before admission into their programs. As Canada is an officially bilingual nation, it is expected that their universities will use either or both English and French. L'Université Laval requires proficiency in French for admission; whereas, UQAM requires a reading and speaking knowledge of French in addition to a reading and oral comprehension knowledge of English. The University of Arizona is unusual in expecting applicants to have prior language teaching experience, but TESL experience could satisfy this requirement. Michigan State University also prefers applicants with second/foreign language teaching experience for their SLA and Language Teaching tract.

Programs vary as to funding from full support for all admitted students to funding primarily for continuing students. There are various forms of fellowships and merit-based support from various levels within a university ranging from departmental to university-wide. The opportunity for funding increases if a student is able to teach beginning language classes, since most programs have Teaching Assistantships (TAs) available in connection with the language programs offered by their institution. Other funding sources include Research Assistantships (RAs), which involve working with faculty on specific research projects; fellowships, which generally do not require work outside of graduate study; and tuition waivers. Most fellowships and assistantships also include tuition remission. In addition to internal funding sources, the opportunities for external funding also exist. The individual universities maintain financial offices that are able to provide external funding sources available to students, including international students. All the departments make an effort to provide some form of funding for their students, although funding may be limited for first year students.

VI Conclusion

There exist a number of schools in the USA and Canada offering opportunities for students interested in SLA. This list is by no means exhaustive, as many schools offering PhDs in linguistics may have at least a member of the faculty working in this area. This survey provides an overview of programs and suggests possible criteria for evaluating them. While there is no one perfect program for developing SLA research, each of the schools in this survey has made a significant contribution to the field. Anyone of these programs will provide a perspective student with the foundation necessary for research into SLA.

Table on

 on

	English Language	Center; Center for	Language	Education and	Research; Less	Commonly Taught	Languages Program	Center for Language	Acquisition					Languages	and Linguistics	(annual conference)			Publishes Arizona	Language Variation Working Papers in SLA Lab Speech	Physiology and FLARE (Forum for	Acoustics Lab Language	Acquisition	Research	Exchange);	Phonetics Lab;	Psycholinguistics	lab	Publishes MIT	Working Papers in	Linguistics (continued)
	PhD in SLS Eight core Language and the	faculty; 23 brain; language	affiliated transfer; Adult	language	acquisition			PhD in Applied 21; seven Second language	Linguistics; MA affiliated processing; L2	in TESL pragmatics	PhD in Linguistics 15; seven in Cognitive linguistics	related and foreign	areas language teaching;	Tense and aspect	in SLA; Input, PhD in Linguistics; 18 with six Phonetics; Computer-	interaction and SLA MA in Linguistics in applied assisted language	PhD in Linguistics; 14 Connectionist models; learning; First Nations languages MA in Linguistics Language aptitude;	L2 writing; Pragmatics PhD in SLA Over 60 from L2 analysis; L2 use;	PhD in Linguistics; 16; five Psycholinguistics; 15 depart-ments MA in Linguistics affiliated Applied French and L2 processing; L2 pedagogical theory	Spanish linguistics PhD in Linguistics; 20 in Cross-linguistic first	PhD in Applied linguistics; and second	PhD in Linguistics; 12 in Language impairment Linguistics; MA in Linguistics MA in Linguistics acquisition in bilinguals; four in applied; 17 associated option with Acquisition of language acquisition; Cognition in second language four in derivational acquisition; Social linguistics morphology; and psychological Acquisition of factors in second phonology; language	PhD in Linguistics 16 Universal Grammar acquisition
	Michigan State Second Language Studies	University						Pennsylvania Linguistics and Applied	State Language Studies Program	University (interdisciplinary)	Rice Linguistics				Simon Fraser Linguistics	University	Indiana University Linguistics;Additional	programs in TESOL	University of and Applied Second Language Acquisition	Louisiana State Arizona Linguistics (interdepartmental and Teaching	University across seven departments)	UCLA Linguistics	Applied Linguistics	McGill Linguistics; PhD Language	Acquisition Program	MIT Linguistics and Philosophy

(continued)

Acknowledgements

I would like to thank the following people for their assistance with information for this article: Robert Bley-Vroman, Craig Chaudron, Stuart Davis, Robert DeKeyser, Scott Delancey, Trude Heift, Alex Marantz, David Prestel, Lyn Repath-Martos, Rod Selby, Matt Shibatani, Margaret Thomas, G. Richard Tucker, Linda Waugh, Lydia White, Kate Wolfe-Quintero, and an anonymous reviewer.


Claudia Felser
email: felsec@essex.ac.uk

Experimental psycholinguistic approaches to second language acquisition

Experimental psycholinguistic approaches to second language acquisition

Claudia Felser University of Essex While interest in issues relating to language processing has been a feature of second language acquisition (SLA) research for some time (see, for example, [START_REF] Mclaughlin | Theories of second language learning[END_REF][START_REF] Vanpatten | Input processing and grammar instruction in second language acquisition[END_REF][START_REF] Pienemann | Language processing and second language development: processability theory[END_REF][START_REF] Carroll | Input and evidence: the raw material of second language acquisition[END_REF], it is only comparatively recently that researchers have begun using experimental psycholinguistic methods to examine the way second language learners process the target language in real time. The aims of this thematic issue are to provide Second Language Research readers with a selective overview of current research in the area of second language (L2) processing, and to demonstrate how the use of on-line psycholinguistic methods can help advance our understanding of certain aspects of SLA.

The use of on-line techniques borrowed from the related disciplines of psychology or neuroscience provides SLA researchers with the opportunity to study aspects of L2 performance that are not otherwise open to direct observation (for overviews of on-line psycholinguistic methods suitable for SLA research see [START_REF] Juffs | Psycholinguistically oriented second language research[END_REF][START_REF] Heredia | On-line methods in bilingual spoken language research[END_REF][START_REF] Marinis | Psycholinguistic techniques in second language acquisition research[END_REF]. Specifically, the experimental psycholinguistic study of L2 processing may help provide answers to the following questions:

• What are the architectures, mechanisms and representations that underlie L2 processing, and how do they differ from those that underlie first language (L1) processing?

• To what extent are learners able to access and integrate different information sources when processing the L2 input?

• What is the time-course of L2 processing, and how does it differ from that of L1 processing? • Do learners transfer processing strategies from their native language to the L2? • How do individual differences in L1 background, age of acquisition, L2 proficiency or working memory capacity influence L2 processing? • Do L2 processing skills develop in conjunction with, or separately from, the L2 grammar?

The four contributions to this issue focus on three of the most commonly used on-line techniques in L2 processing research: self-paced reading (Papadopoulou, Juffs), event-related brain potentials (Mueller) and eye-tracking (Frenck-Mestre). Papadopoulou's article provides an overview of reading-time studies that have investigated ambiguity resolution in the L2. Results from these studies suggest that while L2 learners-like native speakers-are sensitive to lexical-semantic information during L2 processing, even highly proficient learners do not necessarily process ambiguous sentences in a native-like fashion. Papadopoulou also addresses the issues of processing transfer and the role of exposure for L2 sentence processing, both of which, she argues, require further systematic investigation.

In his article, Juffs presents the results from a self-paced reading study on L2 learners' processing of wh-movement structures, comparing learners from different L1 backgrounds and investigating the possible influence of working memory differences on L2 processing. Juffs' findings that all learner groups show subject-object asymmetries in processing wh-extractions, and that learners have difficulty with subject extractions from finite but not from nonfinite clauses, lead him to revise [START_REF] Juffs | Parsing effects in L2 sentence processing: subject and object asymmetries in wh-extraction[END_REF] earlier hypothesis that the absence of overt wh-movement in the L1 may cause difficulties processing wh-subject extractions in the L2.

In her contribution, Mueller reviews the findings from studies that have used event-related brain potentials (ERPs) to investigate lexical, morphosyntactic and phonological processing in the L2. Results from these studies have revealed both similarities and differences between L1 and L2 processing. While lexical-semantic processing appears to be similar in the L1 and the L2, ERP components that are thought to reflect early automatic structure-building processes tend to be absent in late L2 learners. Mueller suggests that the extent to which L2 learners can develop native-like processing patterns may depend crucially on factors such as age of acquisition and L2 proficiency.

In the final contribution to this issue, Frenck-Mestre discusses the results from eye-tracking studies of L2 sentence processing, which, on the whole, point towards similarities rather than differences between L1 and L2 sentence processing. Frenck-Mestre shows how the eye-tracking method compares with the self-paced reading technique, on the one hand, and with ERPs on the other, and emphasizes the need for methodological diversity in the study of L2 processing.

Taken together, the articles in this special issue illustrate how SLA research might benefit from applying on-line methods familiar from the L1 processing literature to the study of L2 processing, and how findings from L2 processing studies might be interpreted in the context of existing psycholinguistic models of language processing.


Jutta L Mueller
email: muellerj@cbs.mpg.de

Electrophysiological correlates of second language processing

The aim of this article is to provide a selective review of eventrelated potential (ERP) research on second language processing. As ERPs have been used in the investigation of a variety of linguistic domains, the reported studies cover different paradigms assessing processing mechanisms in the second language at various levels, ranging from phoneme discrimination to complex sentence processing. Differences between ERP patterns of first language (L1) and second language (L2) speakers can help to specify and to test predictions derived from models of L2 processing or hypotheses concerning critical periods for some aspects of second language acquisition. The studies currently available suggest that ERPs are indeed sensitive to qualitative and quantitative differences in L2 speakers with regard to on-line processing.

I Introduction

Research on language processing has provided interesting insights into the human capacity to decode and integrate different types of linguistic information -such as prosodic, phonemic, semantic, syntactic and pragmatic information -needed in order to comprehend and produce an uncountable variety of meanings. While the nature and time course of the interplay of the different subsystems underlying language processing have not been clarified beyond dispute in first language (L1) processing, even less is known about how second language (L2) speakers process their first and second language. A basic question in second language research is how two or more languages are processed with respect to each other. It could be the case that the L2 forms a completely separate system, relying on completely different processing mechanisms. However, it is equally conceivable that both L1 and L2 have access to either partially overlapping or identical processes. The study of similarities and dissimilarities of first and second language processing has yielded much evidence regarding possible intermediate and end-states in L2 acquisition and the influence of proficiency, as well as other factors on access and use of the L2. Many studies have reported persisting difficulties even in very advanced L2 speakers in the syntactic [START_REF] Johnson | Critical period effects in second language learning: The influence of maturational state on the acquisition of English as a second language[END_REF][START_REF] Weber-Fox | Maturational constraints on functional specializations for language processing: ERP and behavioral evidence in bilingual speakers[END_REF] and phonological domain [START_REF] Flege | Age constraints on second language acquisition[END_REF]. Yet, there are several studies on ultimate attainment in L2 acquisition that report cases of L2 speakers who are indistinguishable from L1 speakers on the basis of their linguistic behaviour in the above mentioned domains, and therefore seem to have reached native-like linguistic skills [START_REF] Birdsong | Ultimate attainment in second language acquisition[END_REF][START_REF] Bongaerts | Ultimate attainment in L2 pronunciation: The case of very advanced late L2 learners[END_REF]. In the lexical domain the most extensively studied question concerns the degree of second language autonomy in lexical access and representation, depending on language context and proficiency level. A number of studies have shown that at least the initial stages of lexical processing in bilinguals are not driven by any one language, but there is also considerable evidence that this might be modified by linguistic and nonlinguistic context and proficiency level (for more detailed information, see [START_REF] Schreuder | The bilingual lexicon[END_REF].

Nonetheless it is important to bear in mind that the absence of differences in behavioural measures taken from L1 and L2 speakers does not necessarily mean that the underlying neural processing mechanisms are the same. Similarly, differences in behavioural measures, such as reaction times, are not necessarily the result of the involvement of different neuronal structures, even if they show qualitatively different patterns. Neurophysiological measures can add valuable information about timing and degree of activation of neural networks and therefore provide physiological correlates of behavioural differences. Therefore the question of convergence or divergence of L1 and L2 processing mechanisms is difficult to solve solely on the basis of behavioural data. Neurophysiological methods directly (Electroencephalography (EEG), Magnetoencephalography (MEG)) or indirectly (Positron Emmission Tomography (PET), functional Magnetic Resonance Imaging (fMRI)) measuring neural activity in the brain during language processing offer a new window into the underlying structures and mechanisms of L2 processing. While methods tied to haemodynamic response such as PET or fMRI provide reliable information about the spatial location of the activated brain region with poor temporal resolution, electrophysiological measures (EEG, MEG) give a very precise real-time measure in the range of milliseconds with poor spatial accuracy. Depending on the research question each methodology can be fruitful in the study of language.

This article is restricted to the specific contributions of event-related potentials (ERPs) for research on L2 processing. Due to methodological constraints in the application of ERPs to the study of language production,1 the studies reported in this review focus on L2 comprehension. After a short introduction to ERP methodology, selected studies of different domains of L2 processing research are reviewed and some possible future directions of research are pointed out.

II ERPs as a measure of language comprehension mechanisms

Language comprehension is characterized by its remarkable speed, despite the high complexity of the input. With a time resolution in the millisecond range, ERPs are a well-suited tool for the investigation of the nature and timing of processes in the short period between encoding of the acoustic signal and comprehension of the utterance. ERPs are small scalp-recorded voltage changes in the continuously measured electroencephalogram (EEG). They are precisely time-locked to an external event that is assumed to be related to the processing mechanism under study. In language research the external event usually comprises the presentation of a visual or auditory speech stimulus. As the signal-to-noise ratio in a single trial event is very small it is necessary to average EEG samples over many trials. The averaging procedure leads to an increase of the event related part of the signal and to a decrease of the part of the signal which is due to random variation (noise). The positive and negative deflections in the ERP, which are typically observed in relation to specific experimental conditions, are referred to as ERP components. ERP components can vary in amplitude, topography, latency, and polarity. Qualitative variations in ERPs of different experimental conditions (i.e., with distinct polarity and/or topography) can either stem from different neural generators or from differences with regard to the relative contribution of the generators [START_REF] Rugg | Functional neuroimaging in cognitive neuroscience[END_REF]. ERPs can therefore help dissociate cognitive operations involved in different conditions on the neural level. However, it is important to keep in mind that similar ERP components do not allow for the conclusion that neural processes are identical. Similarities could also be due to the relative insensitivity of the EEG to a large part of brain activity. In order to produce measurable electrical fields on the scalp surface, nerve cells have to fire synchronously in very large groups and they must be configured in parallel in order to produce a so-called 'open-field'. Due to these restrictions, most of the activity measured by ERPs stems from apical dendrites of pyramidal cells in the cortex. Activity from differently structured neuronal assemblies, as for example from many subcortical brain structures, therefore remains undetected (for more detailed information on ERPs, see [START_REF] Rugg | Electrophysiology of mind: event-related brain potentials and cognition[END_REF] for methodological issues, see [START_REF] Picton | Guidelines for using human event-related potentials to study cognition: recording standards and publication criteria[END_REF]. In the following, ERPs related to specific domains of language processing are introduced and L2 processing studies are reviewed in more detail. As ERP components have proven to be sensitive to different types of linguistic information, they provide information that can help disentangle different subprocesses in language comprehension. As stimuli were presented visually in the majority of studies, modality is mentioned only if it was auditory.

III ERPs in L2 lexical-semantic processing

The most extensively studied ERP component directly linked to language processing is the N400 (see Figure 1a). The N400 was first reported by [START_REF] Kutas | Reading senseless sentences: brain potentials reflect semantic incongruity[END_REF] who visually presented normal sentences ('He spread the warm bread with butter'), sentences containing a semantic anomaly ('He spread the warm bread with socks') and sentences ending with a semantically congruent but physically deviating word, written in capitalized letters ('He spread the warm bread with BUTTER'). They found an enhanced negativity peaking at around 400ms post-stimulus onset time-locked to the semantically incongruent word. The negativity was not present for the physical deviation. Here, a positivity (P300) was observed, a component which has been reported in many other studies in the case of infrequent and task-relevant attended stimuli (Donchin, 1981). The discovery of the N400 stimulated much experimental research regarding the specific nature of its underlying processes. Outright semantic violations are neither necessary nor sufficient for the occurrence of an N400. On the one hand it has been shown that the N400 decreases in amplitude or even vanishes when the same semantic violation is presented repeatedly [START_REF] Besson | An event-related potential (ERP) analysis of semantic congruity and repetition effects in sentences[END_REF]; on the other hand it is observed also for semantically correct words with a low 'cloze probability' that quantifies the expectancy of a specific word at a certain position in a sentence (Kutas and Hillyard, 1984). Moreover, presentation of nonwords leads to an increased N400 [START_REF] Holcomb | Semantic priming in visual and auditory lexical decision: a between modality comparison[END_REF]. In general it can be said that the N400 increases as a function of predictability of a word within its semantic context, which can range from a single word to general world knowledge (for review, see [START_REF] Kutas | Electrophysiology reveals semantic memory use in language comprehension[END_REF]. The N400 has therefore been appreciated as a marker of the difficulty of semantic integration processes. In a series of studies the N400 has been used as a tool for investigating the nature of semantic processing mechanisms in second language learners with different ages of acquistion and proficiency levels. The studies referred to in this section make use of the violation paradigm or the semantic priming paradigm. The violation paradigm tests for semantic integration processes at the sentence level while the semantic priming paradigm tests for lexical processes at the single word level.

First, some studies using semantic violation conditions are summarized. Ardal et al. (1990) visually presented normal and semantically anomalous sentences to fluent bilinguals in their L1 (French) and L2 (English) and to English monolinguals. An N400 was present in all cases, but it was delayed for the bilinguals' L2. [START_REF] Kutas | What is who violating? A reconsideration of linguistic violations in the light of event-related potentials[END_REF] reported similar results, namely a delayed N400 with a reduced amplitude for the less fluent language of bilingual participants. Weber-Fox and [START_REF] Weber-Fox | Maturational constraints on functional specializations for language processing: ERP and behavioral evidence in bilingual speakers[END_REF] investigated the processing of semantic anomalies within sentences as well as syntactic violations in L2 learners who had acquired their L2 (English) at different ages (1-3, 4-6, 7-10, 11-13, Ͼ16 years). The N400 was found for monolinguals and all second language learner groups. However, bilinguals who learned their L2 after the age of 11 showed a delay of the peak latency of approximately 20 ms. [START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF] found an N400 for semantically anomalous words in Russian late L2 learners of German, however, with a reduced amplitude (cf. Figure 1b). [START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF] attributes the difference in the N400 violation effect to an inreased and delayed N400 for semantically normal words in the L2 speakers as she did not find any significant differences in the N400 for anomalous words between L1 and L2 speakers. In a parallel study with native Japanese late learners of German with a comparatively lower proficiency level, Hahne and Friederici (2001) found no significant difference with regard to the N400 between the Japanese L2 speakers of German and native speakers of German.

A paradigm that has been used in a variety of studies to uncover the nature of word-level lexical-semantic processes in the bilingual mental lexicon is the semantic priming paradigm. Semantic priming is described as the facilitation of a response to a target that is semantically related to a preceding prime. Numerous studies have reported semantic priming effects as indicated by response-time (RT) differences within languages in L1 (for review, see [START_REF] Neely | Semantic priming effects in visual word recognition: a selective review of current findings and theories[END_REF] and L2 (e.g., Frenck-Mestre and Prince, 1997), as well as across languages from L1 to L2 and from L2 to L1 (for review, see [START_REF] Kroll | Accessing conceptual representations for words in a second language[END_REF]. In native speakers semantic priming has also been observed to correlate with the N400 component. Semantically unrelated words give rise to an enhanced N400 compared to related words (e.g., [START_REF] Bentin | Event-related potentials associated with semantic priming[END_REF]. Although it is a matter of debate whether the N400 observed in this context represents solely processes of post-lexical integration or also pre-lexical processes such as automatic spreading activation (for review, see [START_REF] Osterhout | Event-related potentials and language comprenension[END_REF] it is interesting to investigate to what degree findings from L1 studies generalize to L2 studies. Furthermore, the priming paradigm also makes the examination of cross-linguistic lexical-semantic effects possible and can therefore be used to test hypotheses of language specifity with regard to lexical and conceptual processing. [START_REF] Kotz | Neurolinguistic evidence for bilingual language representation: a comparison of reaction times and event-related brain potentials[END_REF] and [START_REF] Kotz | The role of proficiency on processing categorical and associative information in the L2 as revealed by reaction times and event-related brain potentials[END_REF] used categorical and associative semantic priming in L2 speakers to test predictions of the revised hierarchical model of the bilingual lexicon [START_REF] Kroll | Category interference in translation and picture naming: evidence for asymmetric connection between bilingual memory representations[END_REF]. This model assumes a weaker conceptual link for L2 words than for L1 words and thus predicts weaker categorical priming effects for L2 speakers as compared to L1 speakers. [START_REF] Kotz | Neurolinguistic evidence for bilingual language representation: a comparison of reaction times and event-related brain potentials[END_REF] tested proficient early L2 learners (age of acquisition Ͻ4 years) of English, while [START_REF] Kotz | The role of proficiency on processing categorical and associative information in the L2 as revealed by reaction times and event-related brain potentials[END_REF] tested late L2 learners of English (age of acquisition Ͼ11 years) with a high or low level of proficiency. Both categorical (heart-liver) and associative priming (heart-love) are known to influence the N400 component in L1 speakers. [START_REF] Kotz | Neurolinguistic evidence for bilingual language representation: a comparison of reaction times and event-related brain potentials[END_REF] reported native-like N400 patterns for categorical and associative priming in early proficient bilinguals, which indicates that word-word and word-concept links in L2 were equally strong in the group of L2 speakers as in natives. Kotz could therefore not confirm the predictions of the revised hierarchical model. [START_REF] Kotz | The role of proficiency on processing categorical and associative information in the L2 as revealed by reaction times and event-related brain potentials[END_REF] found differences between natives and L2 speakers with a high vs. low level of proficiency. L2 speakers showed an N400 effect for associative priming irrespective of proficiency level but no N400 effect for categorical priming. Associative priming led to a longer lasting negativity in the high proficiency group compared to the low proficiency group. The authors interpret this pattern of results as suggesting that the development of a direct link to the conceptual level in L2 is strongly influenced by age of acquisition. Associative priming, on the other hand, was influenced by proficiency level, which is also indicated by an enhanced and longer lasting N400 effect for the high proficiency group [START_REF] Kotz | The role of proficiency on processing categorical and associative information in the L2 as revealed by reaction times and event-related brain potentials[END_REF]. These two studies demonstrate how ERPs can be used to track down subtle differences in semantic processing of an L2 that otherwise might have remained undetected, since the reaction times in the above experiments did not yield any evidence for categorical priming effects for either L1 or L2 speakers.

Besides the investigation of lexical processing mechanisms within L2 or L1 the ERP priming paradigm has been used to investigate language-selective access and degree of top-down control of bilingual lexical processing when two languages possibly compete with each other. The study of interlingual homographs (orthographically identical word forms that have a different meaning in the L1 and L2) can provide information about the influence of a nontarget language on the target language. De Bruijn et al. (2001) tested effects of language context on semantic priming in the L2 (English) of Dutch native speakers. De Bruijn et al. visually presented triplets of words with the first word serving as language context (Dutch vs. English). The following two items functioned as prime and target, and could be semantically related or unrelated in the L2 (house-angel-heaven vs. house-angel-bush). As all primes were interlingual homographs (angel means 'sting' in Dutch) the possible influence of language context -set by the language activated by the first word on the relatedness effect -was put to test. Although semantic relatedness reduced the amplitude of the N400, no influence of the language context could be shown. The authors therefore argue in favour of language nonselective lexical access, as immediate Dutch language context did not inhibit the English meaning of the interlingual homograph. While nonselective access might account for the abovementioned findings within a bilingual language setting, a generalization to other language contexts seems premature. Taking Grosjean's theory of 'language mode' into consideration [START_REF] Grosjean | Processing mixed language: issues, findings, and models[END_REF], one might assume that selectivity of lexical access should vary depending on individual and situational factors.

In summary, the results from ERP studies in the lexical-semantic domain point to similarities between L1 and L2 speakers rather than to differences. The frequent observation of a latency delay or a reduced amplitude of the N400 effect (Ardal et al., 1990;[START_REF] Kutas | What is who violating? A reconsideration of linguistic violations in the light of event-related potentials[END_REF][START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF] suggests that differences between L1 and L2 processing are more quantitative than qualitative in nature. Differences might consist mainly in a slowdown or decrease in efficiency of semantic processing mechanisms. The most striking difference in the N400 between L1 and L2 processing is seen in the absence of the N400 for categorical priming in a late-learnt L2 [START_REF] Kotz | The role of proficiency on processing categorical and associative information in the L2 as revealed by reaction times and event-related brain potentials[END_REF], which indicates that the use of categorical semantic information in L2 is indeed a process that is not easily established in late L2 learning.

IV ERPs in L2 morphological and syntactic processing

The discovery of an ERP component specific for semantic processing has promoted the search for ERP components related to syntactic processing. The pattern that emerged from studies in L1 syntactic processing, however, is less consistent than in the lexical-semantic domain. Many language comprehension studies using syntactic violation conditions have reported negativities that are more pronounced at anterior or left anterior electrodes occurring in the same time window as the N400 (300-500 ms). This component, often referred to as LAN (left anterior negativity), has been found frequently for morphosyntactic errors such as violations of tense, number or gender agreement [START_REF] Weyerts | Brain potentials indicate differences between regular and irregular German plurals[END_REF][START_REF] Coulson | Expect the unexpected: eventrelated brain response to morphosyntactic violations[END_REF]. It has therefore been interpreted as an index of morphosyntactic processing mechanisms [START_REF] Friederici | Towards a neural basis of auditory sentence processing[END_REF]. Another view that has been proposed relates it to more general verbal working memory related processes (e.g., [START_REF] Coulson | Expect the unexpected: eventrelated brain response to morphosyntactic violations[END_REF]. Some more recent studies helped to disentangle the two interpretations by demonstrating that working memory related negativities can be measured globally over the whole sentence, while morphosyntactic LAN effects are measurable only locally after the violated element of the sentence (e.g., [START_REF] King | Who did what and when -using word-level and clause-level ERPs to monitor working-memory usage in reading[END_REF]. In word category violations a very early left anterior negativity (ELAN) with a latency between 100-300 ms has been found [START_REF] Neville | Syntactically based sentence processing classes -evidence from eventrelated brain potentials[END_REF][START_REF] Friederici | Event-related brain potentials during natural speech processing: effects of semantic, morphological and syntactic violations[END_REF][START_REF] Hahne | Electrophysiological evidence for two steps in syntactic analysis: early automatic and late controlled processes[END_REF] (see Figure 2a). The ELAN in response to a word that does not fit the anticipated word category has been interpreted to reflect rapid first-pass parsing processes. The parsing system here is assumed to retrieve only word category information in order to build an initial phrase structure [START_REF] Friederici | Towards a neural basis of auditory sentence processing[END_REF].

Another ERP component that has been reported frequently in the syntactic domain is the P600 or SPS (syntactic positive shift), a positive wave peaking at about 600ms and usually centro-parietally distributed (see Figure 3a). The P600 occurs for syntactic violations [START_REF] Neville | Syntactically based sentence processing classes -evidence from eventrelated brain potentials[END_REF][START_REF] Hahne | Electrophysiological evidence for two steps in syntactic analysis: early automatic and late controlled processes[END_REF] for syntactically complex structures [START_REF] Kaan | The P600 as an index of integration difficulty[END_REF] and for less preferred structures in ambiguous sentences [START_REF] Osterhout | Brain potentials elicited by garden-path sentences -evidence of the application of verb information during parsing[END_REF]. Thus, it has been interpreted as reflecting processes of reanalysis and syntactic repair [START_REF] Osterhout | Brain potentials elicited by garden-path sentences -evidence of the application of verb information during parsing[END_REF][START_REF] Friederici | Towards a neural basis of auditory sentence processing[END_REF]. In a more general way, the P600 is regarded to indicate the difficulty of syntactic integration [START_REF] Kaan | The P600 as an index of integration difficulty[END_REF]. Compared to the (E)LAN, the P600 seems to reflect a higher level of control, as it may be influenced by the percentage of incorrect items within the experiment [START_REF] Hahne | Electrophysiological evidence for two steps in syntactic analysis: early automatic and late controlled processes[END_REF].

The study by Weber-Fox and [START_REF] Weber-Fox | Maturational constraints on functional specializations for language processing: ERP and behavioral evidence in bilingual speakers[END_REF] was the first ERP study with L2 speakers focusing on syntactic processing. The study was designed to test Chinese-English bilinguals for critical period effects in the semantic and the syntactic domain. Participants in the study started using English at different ages (1-3, 4-6, 7-10, 11-13, >16 years of age). Phrases containing word category violations (The scientist criticized Max's of proof the theorem vs. The scientist criticized Max's proof of the theorem) led to both an early (N125) and a later left lateralized negativity (N300-500) in natives. Additionally, a P600 in the time window between 500-700 ms was found for L1 speakers. For the L2 speakers, the pattern differed from that of native speakers irrespective of age of acquisition. Yet, the syntactic ERPs were differentially affected across groups. Interestingly, the early left negativity (N125) was not observed in the L2 learners, except for the group with age of acquisition between 11-13, who showed a reversed left-right topographical distribution. In this group the N125 effect was larger over right scalp sites. The later negativity (N300-500) was present in all L2 groups, but bilaterally distributed if the age of acquisition was greater than 11 years. The P600 effect was similar to native speakers in the groups up to the age of 10 years. The '11-13' years group displayed a delayed positivity starting at about 700 ms and in the group '>16' years no positivity could be found in response to phrase structure violations (at least within the time window of 900 ms post stimulus onset the authors looked at). The authors argued in favour of a differential sensitivity of the syntactic processing system to age of acquisition effects. Neville and colleagues [START_REF] Neville | Fractionating language: different neural subsystems with different sensitive periods[END_REF]Weber-Fox and Neville, 2001) also compared the processing of open-class and closed-class words in L1 and L2 speakers. Open-class words are content words such as nouns or verb stems and closed-class words are grammatical function words. Open-class and closed-class words both elicited negativities in the ERPs, but with different temporal and topographical characteristics. While the negativity for open-class words was broadly distributed and peaked at 350 ms, the negativity for closed-class words was stronger on left anterior electrode sites and peaked earlier (280ms). [START_REF] Neville | Fractionating language: different neural subsystems with different sensitive periods[END_REF], who tested native speakers of American Sign Language (ASL) in their L2 English, did not observe the N280 for closed-class words, while the N350 for open-class words was similar to English native speakers. Weber-Fox and Neville (2001) tested native Chinese L2 speakers with the same material. The negativities for both word classes was observed in the L2 speakers, but the peak latency of the N280 for closed-class words was delayed if the L2 was learnt after the age of 7 years. This was not the case for the N350 for open-class words. Weber-Fox and Neville (2001) noted that possible differences in the proficiency level between the ASL and the Chinese group might account for the observed differences in the N280. Nonetheless both studies indicate a differential susceptibility of function word processing to age of acquisition. However, the presence and topography of the left anterior negativity for the Chinese L2 group suggests that a similar network is involved in L1 and L2 function word processing even if a delay is observed in the L2 speakers. [START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF] and Hahne and Friederici (2001) investigated phrase structure processing in late L2 learners of German. Similar to Weber-Fox and [START_REF] Weber-Fox | Maturational constraints on functional specializations for language processing: ERP and behavioral evidence in bilingual speakers[END_REF] they used word category violations and compared correct sentences (Der König wurde ermordet. 'The king was killed.') to syntactically incorrect sentences (Der König wurde im ermordet. 'The king was in the killed'). During auditory sentence processing native speakers of German show an early left anterior negativity (ELAN) followed by a P600 for syntactically incorrect sentences (see Figures 2a and3a). Hahne and Friederici (2001) reported that native Japanese late L2 learners of German showed neither of the two ERP effects in response to word category violations, but instead showed a greater P600 for the correct sentences as compared to native speakers. To explain the absence of the P600 effect the authors suggest that the L2 speakers might already have to recruit an upper level of processing capacities for the processing of correct sentences, possibly leading to a kind of 'ceiling effect'. Alternatively, one could conclude that Japanese participants recruit first-pass and second-pass parsing processes that are not reflected in any ERP effects. Clearly, in the majority of cases syntactically incorrect sentences were correctly judged as incorrect (76.9%) by the Japanese participants, indicating that the incorrect syntactic structure was identified and processed in some way despite the absence of a P600 modulation.

In contrast to Japanese speakers, native Russian L2 learners of German showed a P600 for syntactically incorrect sentences with a slightly delayed peak latency [START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF]. As was the case in the Japanese group, no ELAN effect was observed for the Russian group (see Figures 2b and3b). These studies indicate that, at least for the emergence of the P600, proficiency might play a crucial role. As reflected in the ratio of correct grammaticality judgements in the syntactic condition (92.9%) the Russian group was more proficient than the Japanese group [START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF]. One additional factor directly or indirectly influencing the ERP differences between the two groups might be related to the presence of similar syntactic structures in the L2 learners' L1. While syntactic structures like those used in the German test sentences (prepositional phrases) are familiar to native Russian speakers, they are unknown to native speakers of Japanese. Nonetheless, there was no indication for the availability of relatively automatic syntactic processes as reflected in the ELAN for either group.

To address the issue of how different native languages influence the learnability of specific syntactic phenomena in the L2, [START_REF] Sabourin | Grammatical gender and second language processing: an ERP study[END_REF] compared the processing of finiteness, subject-verb agreement and grammatical gender violations in native Dutch speakers and German, English and Romance L2 speakers of Dutch. For her native participants Sabourin found a P600 for each condition. The L2 speakers displayed a P600 for the finiteness violation, where incorrect infinitives occurred instead of finite verbs. For subject-verb agreement violations a P600 was found to be similar to natives in the German group, but for the English and the Romance group it was found to be less widely distributed. The most interesting finding of Sabourin's study is the observation that for the gender agreement violation the only group that showed a P600 effect at all was the group with the most similar gender system in the native language, which was the German group. The author suggests that native-like processing mechanisms, as reflected in the P600, are only acquired if the respective grammatical feature is similar in the native language. However, it cannot be ruled out that these ERP differences resulted from subtle differences in proficiency rather than from transfer of processing mechanisms directly, as the German group performed better than the other learner groups in the grammaticality judgement during the experiment. A further problem of Sabourin's study might be the unequal sample size across groups (Dutch: 29; German: 19; English: 17; Romance: 12), which might have hampered the statistical power in the L2 groups. Nonetheless, this study demonstrates how ERPs can be used to test predictions concerning possible transfer processes from L1 to L2.

In a recent study [START_REF] Hahne | Second language learners' processing of inflected words: behavioral and ERP evidence for storage and decomposition[END_REF] investigated the processing of regular and irregular participles and plurals in late L2 learners of German. In native speakers of German it has been found that incorrect applications of regular and irregular suffixes lead to differential ERP effects, namely a LAN (and a P600) for the incorrect use of regular suffixes, and an N400 for incorrect use of irregular suffixes [START_REF] Weyerts | Brain potentials indicate differences between regular and irregular German plurals[END_REF]. Since the LAN can be interpreted as indicating morphosyntactic processes and the N400 as indicating lexical-semantic processes, these findings suggest a dual-route model that assumes rule-based decomposition for regular words and lexical storage for irregular words [START_REF] Pinker | Rules of language[END_REF]. Hahne et al. found that participles and plurals with incorrect irregular suffixes both elicited an N400 in L2 speakers. Whereas incorrect regular suffixes led to a LAN and a P600 effect in the participle system, only a P600 was found for plurals with incorrect regular suffixes. The authors argue that, as for native speakers, two processing routes are available to L2 speakers. Hahne et al. point to the increased difficulty for L2 speakers of German in processing plurals vs. participles to explain the absence of the LAN for incorrectly applied regular plural suffixes. The development of relatively automatic morphosyntactic processes therefore seems possible but may be influenced by the complexity of the morphosyntactic domain under study.

The correlation between proficiency and certain syntactic ERP effects is also underlined by a study conducted by [START_REF] Friederici | Brain signatures of artificial language processing: evidence challenging the critical period hypothesis[END_REF] on auditory processing of an artificially constructed miniature language (Brocanto). Due to the small size of Brocanto (14 lexical elements), the participants, whose native language was German, were able to achieve a high level of performance in the production and comprehension of Brocanto sentences. After learning, participants were presented correct Brocanto sentences and sentences containing word category violations. A biphasic ERP pattern consisting of an early anterior negativity and a P600 was found in response to violations of phrase structure rules even for structures that were totally new to the learners and could not be transferred from the L1. This finding is in concord with the assumption that proficiency plays a major role in the development of neural correlates of syntactic processing. However, it is not clear if mechanisms underlying artificial language processing are qualitatively the same as processes underlying natural language processing. A first study by [START_REF] Mueller | Electrophysiological correlates of syntactic and thematic processing in a miniature language: how different are learners from natives? 11th Annual Meeting of the Cognitive Neuroscience Society[END_REF] using a miniature language paradigm with naturally spoken Japanese sentences revealed differences between Japanese native speakers and learners of the miniature Japanese in syntactic ERP patterns. Participants reached a high proficiency level, but did not display an anteriorily focused negativity as was seen for word category violations in Japanese participants. However, a P600 was observed for the same conditions in both groups of participants (natives and learners).

In sum, the picture regarding syntactic ERP effects in L2 learners is twofold. On the one hand, some striking similarities to native speakers were discovered, notably the P600 (Weber-Fox and [START_REF] Weber-Fox | Maturational constraints on functional specializations for language processing: ERP and behavioral evidence in bilingual speakers[END_REF][START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF][START_REF] Hahne | Second language learners' processing of inflected words: behavioral and ERP evidence for storage and decomposition[END_REF][START_REF] Sabourin | Grammatical gender and second language processing: an ERP study[END_REF], which suggests that more controlled syntactic parsing processes can at least in principle be acquired in a number of grammatical domains. On the other hand, the processes underlying the ELAN or LAN effect seem to be comparatively difficult to acquire if the L2 is learnt late [START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF]Hahne and Friederici, 2001;[START_REF] Weber-Fox | Maturational constraints on functional specializations for language processing: ERP and behavioral evidence in bilingual speakers[END_REF]. Studies using (artificial) miniature languages that ensure a very high proficiency level of the trained participants [START_REF] Friederici | Brain signatures of artificial language processing: evidence challenging the critical period hypothesis[END_REF][START_REF] Mueller | Electrophysiological correlates of syntactic and thematic processing in a miniature language: how different are learners from natives? 11th Annual Meeting of the Cognitive Neuroscience Society[END_REF], as well as studies of near-native L2 speakers seem to be a promising area of research that could help specify conditions necessary for the development of specific syntactic ERP components.

V ERPs in L2 speech sound categorization and segmentation

There is a limited number of studies on L2 speakers that investigate comprehension processes preceding lexical-semantic and syntactic analysis. Before the listener can assign structure and meaning to a given speech stream he or she must distinguish relevant phonemes accurately and detect the onset and offset of words. An ERP component that is sensitive to detection of changes in the auditory modality is the mismatch negativity (MMN), peaking at 100-250 ms post stimulus onset. It is measurable when physically 'deviating' stimuli are presented randomly in sequences of very frequent 'standard' stimuli. Elicitation of the MMN does not require participants to listen actively to the stimulus, and has been interpreted as an index of pre-attentive processes (for review, see [START_REF] Näätänen | The perception of speech sounds by the human brain as reflected by the mismatch negativity (MMN) and its magnetic equivalent (MMNm)[END_REF]. Its independence from conscious attention makes it suitable to study language processing mechanisms even in young children. It has been shown that the MMN is not only sensitive to acoustic stimulus properties, but also to categorical distinctions between speech sounds. [START_REF] Näätänen | Language-specific phoneme representations revealed by electric and magnetic brain responses[END_REF] have shown that the amplitude of the MMN increases if standard and deviant stimuli are phoneme prototypes of the native language. The language specific MMN is probably based on the formation of permanent memory traces for the native language phonemes within the first year of life [START_REF] Cheour | Development of language-specific phoneme representations in the infant brain[END_REF]. For second language learners the acquisition of appropriate distinctions between L2 phonemes is crucial. Cheour and colleagues [START_REF] Cheour | Mismatch negativity shows that 3-6-year-old children can learn to discriminate non-native speech sounds within two months[END_REF][START_REF] Shestakova | Event-related potentials associated with second language learning in children[END_REF] conducted a longitudinal study on second language learning in 3-6-year-old children who learned French in a schoollike setting. They showed that within two months training 3-6-year-old Finnish children developed a full MMN response to vowel categories specific to French, which was not present in children without teaching. When looking at late L2 learners, [START_REF] Winkler | Brain responses reveal the learning of foreign language phonemes[END_REF] reported a native-like MMN in response to a L2 specific phoneme distinction. Proficient Hungarian late second language learners of Finnish displayed the MMN for a vowel distinction that is relevant in Finnish but not in Hungarian. The MMN for this distinction was not present in Hungarian speakers with no command of Finnish [START_REF] Winkler | Brain responses reveal the learning of foreign language phonemes[END_REF].

These findings show that the categorization processes reflected in the MMN can be learnt during and after childhood and are not necessarily hampered by late age of acquisition (>12 years). It is questionable, however, whether this holds true for all possible phoneme distinctions across languages. Results of a study conducted by [START_REF] Nenonen | Linguistic relevance of duration within native language determines the accuracy of speech-sound duration processing[END_REF] give rise to a less optimistic view. In their study the processing of duration in speech and nonspeech stimuli was tested in native Finnish children and Russian children who arrived in Finland after the age of 4 years. In the Finnish language long and short vowels distinguish reflect the Japanese participants' use of L1 processing strategies that differ from those used by native speakers of English.

In sum, the above reviewed studies suggest that some new phoneme distinctions -as for example new vowel categories -can be acquired in L2 acquisition [START_REF] Cheour | Development of language-specific phoneme representations in the infant brain[END_REF][START_REF] Winkler | Brain responses reveal the learning of foreign language phonemes[END_REF][START_REF] Shestakova | Event-related potentials associated with second language learning in children[END_REF] while other distinctions -such as distinctions based solely on the duration parameter [START_REF] Nenonen | Linguistic relevance of duration within native language determines the accuracy of speech-sound duration processing[END_REF] -might be more difficult to establish in L2 acquisition. The first ERP study of the N100 for speech segmentation in L2 speakers [START_REF] Sanders | An ERP study of continuous speech processing II: segmentation, semantics and syntax in nonnative speakers[END_REF] suggests that native-like speech segmentation mechanisms cannot be used by late L2 learners, at least in those cases where the L1-L2 pairing precludes the transfer of segmentation strategies from the learners' L1.

VI Conclusions and outlook

In the last decades ERPs have become increasingly important as a tool for measuring language-related brain processes. ERP components that are thought to reflect specific functions in native language comprehension can be used as an objective measure of these functions in different groups of language users, such as L2 speakers of various proficiency levels and age of acquisition groups. Theories -such as the revised hierarchical model [START_REF] Kroll | Category interference in translation and picture naming: evidence for asymmetric connection between bilingual memory representations[END_REF], which predicts problems with categorical-semantic processing in (less advanced) L2 speakers, or the declarative/procedural model [START_REF] Ullman | The neural basis of lexicon and grammar in first and second language: The declarative/procedural model[END_REF], which hypothesizes an increased reliance on lexical storage based processes as compared to automatized syntactic processes for L2 speakers -can be put to test in ERP studies.

From the available studies the developmental order of ERP markers of language processing in L2 and the degree of variability of developmental trajectories can also be speculated upon. It is probable that highly automatic syntactic processes, as indexed by the ELAN or LAN, are not available until more controlled syntactic and semantic processes, as indicated by the P600 and the N400, are established, if they are acquired at all by late L2 learners. It is equally conceivable that similar interdependencies exist with respect to the presence of ERPs in segmental processing or phonological discrimination.

Given an adequate interpretation of their functional characteristics, ERPs can be regarded as a powerful instrument in diagnosing of areas of difficulty for L2 learners and in identifying domains in which native-like language comprehension processes are not normally attained. Moreover, ERP patterns observed in L2 speakers can also help to further clarify the general nature of the respective ERP components in L1 speakers. The case of the ELAN component, which has not yet been reported for L2 speakers, underlines that the development of the underlying process requires either a lot of time and practice or specific biological prerequisites available only in early childhood. In contrast to the difficulty in the acquisition of rather automatic syntactic processing mechanisms, the P600, which reflects more controlled syntactic processes, has been found in advanced L2 speakers of several languages. The available studies suggest that the P600 is strongly affected by the actual proficiency level of the L2 speakers [START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF]Hahne and Friederici, 2001;[START_REF] Sabourin | Grammatical gender and second language processing: an ERP study[END_REF]. Thus, the prerequisites for the acquisition of the process indexed by the P600 seem to be principally available to late L2 learners.

To summarize, ERP studies of second language processing have shed light on processing differences between native and L2 speakers. Factors such as age of acquisition or proficiency level seem to play a crucial role in determining similarity or dissimilarity of ERP patterns in native and L2 speakers. Careful control of the variables that might influence L2 processing -such as learning environment, amount of L1 and L2 use, or learning motivation -might help to further elucidate the nature of differences between L1 and L2 speakers with respect to ERPs. The specification of the prerequisites for the development of 'nativelike' ERP patterns appears to be a promising field for future investigations.

Figure 1

 1 Figure 1 N400 in native speakers (a) and Russian L2 speakers (b) of German.Semantically anomalous words (dotted line) elicit a larger N400 at a central electrode position (CZ) than semantically normal words (solid line) (adapted from[START_REF] Hahne | What's different in second language processing? Evidence from event-related brain potentials[END_REF]

Figure 2 Figure 3

 23 Figure 2 ERPs in response to syntactically correct and incorrect sentences in native speakers (a) and Russian L2 speakers (b) of German. Syntactically incorrect words (dotted line) elicit a larger ELAN at a left anterior electrode position (F7) than syntactically correct words only in German native speakers (solid line) (adapted from Hahne, 2001)

ERPs cannot be recorded during natural speech production as articulatory movements cause musculary induced artifacts in the signal. The same is true for eye movements and blinks, which should be avoided during the ERP epoch or mathematically corrected.

Acknowledgements

For helpful comments and suggestions on previous versions of this article, I would like to thank Claudia Felser, Angela D. Friederici, Anja K. Ischebeck, Sonja A. Kotz, Shirley-Ann Rüschemeyer and an anonymous Second Language Research reviewer.

between the meaning of words and are therefore to be considered different phonemes (e.g., /tuli/ 'fire' vs. /tu:li/ 'wind'), which is not the case in Russian. Nenonen et al. presented the long and short syllable /ka:/ vs. /ka/ and a long and short complex tone as standard and deviant in blocks. The duration difference in both conditions was 50ms. Whereas the MMN response to the deviant tone did not differ between native and L2 speakers, the MMN related to phoneme distinction was decreased in amplitude in the L2 speakers. The authors take this difference as evidence that acoustic change detection is comparable in the L1 and the L2 speakers but that 'fine tuning in the processing of speech-sound duration may be inhibited at the pre-attentive level' (Nenonen, 2003: 494) in the L2. This finding is of particular interest as the participants tested can be considered early L2 learners. Studies currently available seem to suggest that phonemic features differ with regard to their learnability in L2 acquisition and that there might be differential age and proficiency constraints for different distinctive features.

Recently an ERP component has been reported that possibly indicates speech segmentation processes independent of acoustic cues [START_REF] Sanders | Segmenting nonsense: an event-related potential index of perceived onsets in continuous speech[END_REF][START_REF] Sanders | An ERP study of continuous speech processing II: segmentation, semantics and syntax in nonnative speakers[END_REF]. As languages use different rhythmical cues for segmenting speech -such as syllables, morae and stress -it has been questioned if L2 speakers with a rhythmically different L1 use the same rhythmic segmentation cues as native speakers. Efficient speech segmentation could be a prerequisite for the acquisition of native-like efficiency with regard to syntactic and semantic processing. [START_REF] Sanders | An ERP study of continuous speech processing II: segmentation, semantics and syntax in nonnative speakers[END_REF] reported an enhanced N100 (a negativity 100ms post stimulus onset) for word initial syllables compared to physically matched word medial syllables for native speakers of English. A similar N100 effect has been observed comparing stressed and unstressed syllables. Neither effect has been observed for late Japanese L2 learners of English (age of acquisition >12 years). The authors concluded that the L2 speakers neither segmented speech in a native-like manner nor did they use stress information (which is carried by the parameters loudness, duration and pitch) in the way natives do. As the native language of the group investigated by Sanders et al. is considered to be mora-timed, it relies probably less on syllable and stress information as other languages. The absence of the N100 effects could then be a result of the delay in language learning itself, or could

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