DeKeyser, Robert PATRICK REBUSCHAT Robert DeKeyser is a Belgian applied linguist who is best known for his influential research and publications on the cognitive aspects underlying second language acquisition (SLA) and teaching. DeKeyser’s work covers a variety of topics, including implicit and explicit learning, the role of practice in second language (L2) acquisition, language learning in study-abroad settings, and age effects in L2 acquisition. The linguistic focus in DeKeyser’s work is usually on the acquisition of L2 morphosyntax (see, e.g., DeKeyser, 1995, 1997, 1998, 2005a; Goldschneider & DeKeyser, 2001). His research has been funded by many grants, including highly competitive awards from the National Institutes of Health, the Spencer Foundation, and the United States Department of Education. DeKeyser was born in Varsenare, Belgium, in 1957. He pursued his undergraduate studies at the Catholic University of Leuven, where he obtained a BA in Romance Philology (1979), a Diploma in Spanish Studies (1979), a Certificate of Specialization in Psycholinguistics (1980), and his teaching credentials (French, 1980). He then moved to the United States to study at Stanford University, where he first obtained an MA (1982) and then a PhD in Education, with a minor in Linguistics (1986). After his doctorate, DeKeyser returned to Belgium to work on a research project funded by the Belgian National Science Foundation, before returning to the United States in 1988 to take up a faculty position at the Department of Linguistics, University of Pittsburgh. He moved to the University of Maryland, College Park, in 2005, where he is currently professor of Second Language Acquisition. DeKeyser has published a substantial number of widely cited studies in journals such as Studies in Second Language Acquisition, Language Learning, Applied Psycholinguistics, TESOL Quarterly, Annual Review of Applied Linguistics, Modern Language Journal, and Language Testing. He has contributed a large number of invited chapters to influential state-of-the art volumes (e.g., Doughty & Williams, 1998; Robinson, 2001) and handbooks (e.g., Doughty & Long, 2003; Kroll & de Groot, 2005). DeKeyser’s review articles have been particularly influential and represent the first—and sometimes the only—port of call for researchers and students interested in major topics in SLA, for example automaticity and automatization (DeKeyser, 2001), implicit and explicit learning (DeKeyser, 2003), age effects in L2 acquisition (DeKeyser & Larson-Hall, 2005; DeKeyser, in press), and skill acquisition theory (DeKeyser, 2007a). In addition to his article publications, DeKeyser also edited three influential volumes, Practice in a second language (DeKeyser, 2007b), Morphosyntactic development in second language learning (2005b), and Testing second language acquisition theory in the lab (Hulstijn & DeKeyser, 1997). DeKeyser is also well known for his extensive service to the profession, especially in his role as editor of Language Learning (2005–10), one of the flagship journals in the field. He is on the advisory board of several book series and the co-editor of the Studies in Bilingualism series, published by John Benjamins. He has also served as external PhD examiner and external referee for promotion and tenure committees at many universities, and as ad hoc reviewer for funding bodies. The Encyclopedia of Applied Linguistics, Edited by Carol A. Chapelle. © 2013 Blackwell Publishing Ltd. Published 2013 by Blackwell Publishing Ltd. DOI: 10.1002/9781405198431.wbeal0311 2 dekeyser, robert Topics and Ideas Age Effects in Second Language Acquisition One of the most widely debated questions in SLA research concerns the role of age in L2 acquisition. The debate focuses on a key difference between first and second language acquisition, namely the fact that language acquisition in childhood usually results in native-like competence in one or more languages, whereas language acquisition in adulthood is unlikely to be as successful. This difference between child and adult learners, also known as the age-of-acquisition (AoA) effect, has often been explained in terms of a critical period for language development. The idea that there might be a critical age period for the acquisition of language is usually traced back to researchers such as Lenneberg. According to Lenneberg (1967), language acquisition from mere exposure to the linguistic environment is only possible before the critical period. After this period, learners cannot rely on the same learning mechanism to acquire language, with the consequence that their levels of ultimate attainment in the L2 will necessarily fall short of native-like ability. The debate has centered on a series of questions, for example: Is there a critical period for language acquisition, as suggested by Lenneberg (1967), or can the age effects in L2 acquisition be explained by other factors (differences in quality and quantity of input, practice, social-psychological factors, etc.)? If there is a critical period, when does this period occur and how should it be explained? How does age affect the acquisition of the different elements of language (syntax, morphology, phonology, lexicon, etc.)? While these and other questions continue to be subject to debate, there is empirical evidence to suggest that younger learners do, in fact, have an advantage in ultimate attainment (though not in rate of learning), and that this advantage holds for both pronunciation and grammar learning. The decline of language learning ability seems to take place gradually, from ages 6–7 to 16–17. And, importantly, it appears that the AoA effect cannot be fully explained by factors such as input, use of L1 and L2, social-psychological factors, or length of residence. For comprehensive reviews of the literature see DeKeyser and Larson-Hall (2005) and DeKeyser (in press). DeKeyser has been an active contributor to the debate on age effects in L2 acquisition (see, e.g., DeKeyser, 2000, 2007a). One of his widely cited studies, DeKeyser (2000), had two aims. The first was to extend Johnson and Newport’s (1989) correlational study. Johnson and Newport asked native speakers of Chinese and Korean who had immigrated to the United States at various ages (3–39) to perform on an auditory grammaticality judgment test. Performance on the latter was used to assess their knowledge of a range of morphosyntactic structures in English. This allowed them to relate proficiency (as measured by performance on the grammaticality judgments) to the age at which subjects began learning L2 English. Johnson and Newport found a strong negative correlation of -.77 between AoA and L2 proficiency. DeKeyser (2000) extended this study by looking at a different population and avoiding certain methodological problems. Another aim of DeKeyser (2000) was to test the fundamental difference hypothesis (Bley-Vroman, 1988), which states that, while children are able to learn their native language(s) through implicit learning mechanisms, adults have largely lost this ability and have to rely on general learning mechanisms and analytic abilities instead. If this is the case, then one might expect verbal aptitude to play an important role in adult, but not in child, language learning. DeKeyser thus sought to determine whether the aptitude effect varies with age and the age effect with aptitude. DeKeyser (2000) recruited 57 native speakers of Hungarian who were residing in the United States. The age of arrival range was 1–40, all participants had resided in the US for at least 10 years (average length of residence 34 years), and levels of education and occupational status varied widely. Subjects performed on an adapted version of Johnson dekeyser, robert 3 and Newport’s (1989) grammaticality judgment test. In addition, subjects also completed a Hungarian verbal ability test (Ottó, 1996). DeKeyser found a strong negative correlation between AoA and proficiency (as assessed by the grammaticality judgments), r = -.63, which replicated Johnson and Newport’s (1989) findings. DeKeyser also found that, after the age of 16, only those learners with high verbal aptitude scores also achieved high scores on the grammaticality judgment test. This suggests that the only way that an adult learner can achieve grammatical competence similar to that of a native speaker is by using analytical, problem-solving abilities, as predicted by the fundamental difference hypothesis. Aptitude does not predict ultimate attainment by child learners because the latter can rely on implicit learning mechanisms. More recently, DeKeyser, Alfi-Shabtay, and Ravid (2010) provide crosslinguistic support for these findings. Second Language Acquisition as Skill Learning If language acquisition in adults is qualitatively different, then how can this process be characterized? DeKeyser contributed to this question in several studies, the most influential being his experiment on the automatization of explicit L2 grammar rules. DeKeyser (1997) trained 61 subjects on an artificial language (Autopractan) that consisted of 32 vocabulary items and four morphosyntactic rules. At the beginning, subjects received explicit training on how the artificial language worked. Once they reached criterion on a set of metalinguistic tests, subjects received comprehension and production training for a period of eight weeks. Comprehension practice consisted of choosing between pictures displayed on a computer screen to match a sentence. Production practice consisted of typing the correct sentence corresponding to the picture. Subjects were divided into three groups: Group A received comprehension practice on rules 1 and 2, and production practice on rules 3 and 4. Group B did the reverse, that is, comprehension practice on rules 3 and 4 and production practice on rules 1 and 2. Group C received comprehension and production practice on all four rules. DeKeyser (1997) found that the learning of morphosyntactic rules was highly skillspecific, that is, large amounts of practice in comprehension and production led to great improvements in the practiced skill but not in the reverse skill. Importantly, he also found that these skills develop gradually over time, following the same power function learning curve as the acquisition of other cognitive domains (e.g., geometry, computer programming). DeKeyser (1997) interpreted these results as being consistent with skill acquisition theory, an information-processing approach that defines learning as the gradual conversion of declarative (explicit) knowledge into procedural (implicit) knowledge by means of practice (automatization) (see DeKeyser, 2001, for an overview). Conclusion DeKeyser’s work has important implications for our understanding of L2 acquisition. His work on age effects has provided strong evidence for a quantitative decline of language learning ability and a qualitative shift in learning mechanisms (implicit vs. explicit) as a function of age before adulthood, at least for the case of morphosyntax. Moreover, his research on L2 acquisition has shown that providing adults with explicit knowledge can be beneficial, assuming this is followed by ample opportunities to practice. DeKeyser’s work thus provides evidence for an interface between explicit and implicit knowledge. Furthermore, DeKeyser’s research suggests that adult L2 acquisition can, in fact, be conceived of as an explicit learning process, that is, a learning process in which subjects rely on their analytic abilities and not on an implicit process of induction. This process is skillspecific and highly dependent on language aptitude, with adult learners who score high on verbal ability measures significantly outperforming learners with low verbal ability 4 dekeyser, robert scores. In terms of pedagogical implications, DeKeyser’s (2000, 2010) observation that explicit learning processes are a necessary condition for achieving a high degree of proficiency in the L2 after childhood suggests that teaching approaches that deny adult learners the value of explicit, form-focused instruction are flawed. His work on automatization confirms that there is, in fact, a place for systematic and extended practice of rules in the teaching curriculum. SEE ALSO: Automatization, Skill Acquisition, and Practice in Second Language Acquisition; Critical Period; Explicit Knowledge and Grammar Explanation in Second Language Instruction; Explicit Learning in Second Language Acquisition; Practice in Second Language Instruction References Bley-Vroman, R. (1988). The fundamental character of foreign language learning. In W. Rutherford & M. Sharwood Smith (Eds.), Grammar and second language teaching: A book of readings (pp. 19–30). Rowley, MA: Newbury House. DeKeyser, R. (1995). Learning second language grammar rules: An experiment with a miniature linguistic system. Studies in Second Language Acquisition, 17, 379–410. DeKeyser, R. (1997). Beyond explicit rule learning: Automatizing second language morphosyntax. Studies in Second Language Acquisition, 19, 195–221. DeKeyser, R. (1998). Beyond focus on form: Cognitive perspectives on learning and practicing second language grammar. In C. Doughty & J. Williams (Eds.), Focus on form in classroom language acquisition (pp. 42–63). New York, NY: Cambridge University Press. DeKeyser, R. (2000). The robustness of critical period effects in second language acquisition. Studies in Second Language Acquisition, 22, 499–533. DeKeyser, R. (2001). Automaticity and automatization. In P. Robinson (Ed.), Cognition and second language instruction (pp. 125–51). New York, NY: Cambridge University Press. DeKeyser, R. (2003). Implicit and explicit learning. In C. Doughty & M. Long (Eds.), Handbook of second language acquisition (pp. 313–48). Oxford, England: Blackwell. DeKeyser, R. (2005a). What makes second-language grammar difficult? A review of issues. Language Learning, 55, 1–25. DeKeyser, R. (Ed.). (2005b) Morphosyntactic development in second language learning. (Special issue) Language Learning, 55. DeKeyser, R. (2007a) Skill acquisition theory. In J. Williams and B. VanPatten (Eds.), Theories in second language acquisition: An introduction (pp. 97–113). Mahwah, NJ: Erlbaum. DeKeyser, Robert (Ed.). (2007b). Practice in a second language: Perspectives from applied linguistics and cognitive psychology. New York, NY: Cambridge University Press. DeKeyser, R. (in press). Age effects in second language learning. In S. Gass & A. Mackey (Eds.), Handbook of second language acquisition. London, England: Routledge. DeKeyser, R., Alfi-Shabtay, I., & Ravid, D. (2010). Cross-linguistic evidence for the nature of age effects in second language acquisition. Applied Psycholinguistics, 31, 413–38. DeKeyser, R., & Larson-Hall, J. (2005). What does the critical period really mean? In J. F. Kroll & A. M. B. De Groot (Eds.), Handbook of bilingualism: Psycholinguistic approaches (pp. 88–108). Oxford, England: Oxford University Press. Doughty, C., & Long, M. (Eds.). (2003). Handbook of second language acquisition. Oxford, England: Blackwell. Doughty, C., & Williams, J. (Eds.). (1998). Focus on form in classroom language acquisition. New York, NY: Cambridge University Press Goldschneider, J. & R. DeKeyser (2001). Explaining the “natural order of L2 morpheme acquisition” in English: A meta-analysis of multiple determinants. Language Learning, 51, 1–50. dekeyser, robert 5 Hulstijn, J., & R. DeKeyser (Eds.). (1997). Testing second language acquisition theory in the lab. (Special issue) Studies in Second Language Acquisition, 19. Johnson, J. S., & Newport, E. L. (1989). Critical period effects in second language learning: The influence of maturational state on the acquisition of English as a second language. Cognitive Psychology, 21, 60–99. Kroll, J. F., & De Groot, A. M. B. (Eds.). (2005). Handbook of bilingualism: Psycholinguistic approaches. Oxford: Oxford University Press Lenneberg, E. H. (1967). Biological foundations of language. New York, NY: Wiley. Ottó, I. (1996b). Hungarian language aptitude test: Words in sentences (Unpublished manuscript). Department of English Applied Linguistics, Eötvös Loránd University, Budapest. Robinson, P. (Ed.). (2001). Cognition and second language instruction. New York, NY: Cambridge University Press. Suggested Readings Anderson, J. R. (1983). The architecture of cognition. Cambridge, MA: Harvard University Press. DeKeyser, R. (2009). Cognitive-psychological processes in second language learning. In M. Long & C. Doughty (Eds.), Handbook of second language teaching (pp. 119–38). Oxford, England: Blackwell. Singleton, D. (2001). Age and second language acquisition. Annual Review of Applied Linguistics, 21, 77–89.