July 1, 2015; Vol. 36, No. 3

Introduction: Complementarity in Research Syntheses
Rod Ellis
Applied Linguistics 2015 36: 285-289
This special issue of Applied Linguistics has two primary goals: The first is to examine the complementarity of two types of research synthesis—traditional narrative reviews and meta-analysis. The second is to accumulate information from primary studies on the role that instruction plays in second language learning. The topics addressed in the six articles come from the field of SLA: two were relatively broadly defined (language aptitude and L2 pronunciation instruction) and one more narrowly (Processing Instruction). In this introduction, I will focus on the complementarity of the methodology of these two ways of conducting research synthesis.

The Effectiveness of Processing Instruction in L2 Grammar Acquisition: A Narrative Review
Robert Dekeyser and Goretti Prieto Botana
Applied Linguistics 2015 36: 290-305
The past two decades have seen ample debate about processing instruction (PI) and its various components. In this article, we first describe what PI consists of and then address three questions: about the role of explicit information (EI) in PI, the difference between PI and teaching that incorporates production-based (PB) practice, and various factors that may moderate the impact of these treatments. Our review shows that while many studies find little difference between PI with and without EI and between PI and PB, the results vary depending on whether the comprehension practice (structured input; SI) is task-essential or not and whether the PB is communicative or not. Furthermore, PI tends to favor comprehension abilities and PB production abilities. This review also shows that almost all PI research so far has been very short-term and limited to a narrow range of structures and populations, typically American college students learning a foreign language. Therefore the implications that some have drawn from the PI literature, namely, that neither EI nor production practice help beyond SI, are still far from generalizable.

The Effectiveness of Processing Instruction and Production-based Instruction on L2 Grammar Acquisition: A Meta-Analysis
Natsuko Shintani
Applied Linguistics 2015 36: 306-325
This article reports a meta-analysis of 42 experiments in 33 published studies involving processing instruction (PI) and production-based instruction (PB) used in the PI studies. The comparative effectiveness of PI and PB showed that although PI was more effective than PB for developing receptive knowledge, PB was just as effective as PI for productive knowledge. Furthermore, the PB proved superior to the PI for productive knowledge when both groups received the same explicit information. The moderator analyses showed that: (i) the long term effects of PI and PB differed; (ii) PI was more effective for adults than for adolescent learners while PB was equally effective for both age groups; (iii) the effectiveness of PI was not influenced by the provision of explicit explanation and strategy training; (iv) the effectiveness of PB for receptive knowledge was influenced by strategy training; and (v) both PI and PB proved more effective in the production tests when the instruction focused on the meaning primacy principle than the first noun principle while no differences were found in the receptive tests.

The Effectiveness of L2 Pronunciation Instruction: A Narrative Review
Ron I. Thomson and Tracey M. Derwing
Applied Linguistics 2015 36: 326-344
Research on the efficacy of second language (L2) pronunciation instruction has produced mixed results, despite reports of significant improvement in many studies. Possible explanations for divergent outcomes include learner individual differences, goals and foci of instruction, type and duration of instructional input, and assessment procedures. After identifying key concepts, we survey 75 L2 pronunciation studies, particularly their methods and results. Despite a move towards emphasizing speech intelligibility and comprehensibility, most research surveyed promoted native-like pronunciation as the target. Although most studies entailed classroom instruction, many featured Computer Assisted Pronunciation Teaching (CAPT). Segmentals were studied more often than suprasegmentals. The amount of instruction required to effect change was related to researchers’ goals; interventions focusing on a single feature were generally shorter than those addressing more issues. Reading-aloud tasks were the most common form of assessment; very few studies measured spontaneous speech. The attribution of improvement as a result of instruction was compromised in some instances by lack of a control group. We summarize our findings, highlight limitations of current research, and offer suggestions for future directions.

The Effectiveness of Second Language Pronunciation Instruction: A Meta-Analysis
Junkyu Lee, Juhyun Jang, and Luke Plonsky
Applied Linguistics 2015 36: 345-366
The goal of this study was to determine the overall effects of pronunciation instruction (PI) as well as the sources and extent of variance in observed effects. Toward this end, a comprehensive search for primary studies was conducted, yielding 86 unique reports testing the effects of PI. Each study was then coded on substantive and methodological features as well as study outcomes (Cohen’s d). Aggregated results showed a generally large effect for PI (d = 0.89 and 0.80 for N-weighted within- and between-group contrasts, respectively). In addition, moderator analyses revealed larger effects for (i) longer interventions, (ii) treatments providing feedback, and (iii) more controlled outcome measures. We interpret these and other results with respect to their practical and pedagogical relevance. We also discuss the findings in relation to instructed second language acquisition research generally and in comparison with other reviews of PI (e.g. Saito 2012). Our conclusion points out areas of PI research in need of further empirical attention and methodological refinement.

Foreign Language Aptitude and Its Relationship with Grammar: A Critical Overview
Peter Skehan
Applied Linguistics 2015 36: 367-384
This article presents a critical overview of research studies which link foreign language aptitude to grammar. It starts by covering fundamental issues—of the structure of aptitude and its measurement. It is argued that the concept of aptitude needs to be updated, and that clear linkages to second language acquisition processes need to be established. The major sections of the article review research on aptitude and pedagogy, and aptitude as relevant to understanding sensitive period effects. With pedagogy, recent articles regarding instructional options and also research linking aptitude to feedback are reviewed. With a sensitive period, the discussion is of aptitude as a potential negator of such an effect, as well as the possibility that aptitude may be linked to second language learning success with younger learners. Suggestions are offered for a reconfiguration of the place of aptitude within second language acquisition.

The Associations Between Language Aptitude and Second Language Grammar Acquisition: A Meta-Analytic Review of Five Decades of Research
Shaofeng Li
Applied Linguistics 2015 36: 385-408
This study reports a meta-analysis that synthesizes the empirical research on the role of language aptitude in second language grammar acquisition. A total of 33 study reports were identified including 17 predictive studies that investigated the correlations between aptitude and ultimate L2 attainment and 16 interactional studies that examined the interface between aptitude and the effectiveness of instructional treatments. These studies generated 309 effect sizes and involved 3,106 L2 learners. It was found that aptitude showed an overall moderate association with L2 grammar learning, r = .31, 95% CI = .25–.36. Subsequent moderator analysis demonstrated that high school students were more likely to draw on aptitude than university students and that aptitude was more strongly correlated with explicit treatments than implicit treatments. The role of aptitude was more evident for younger learners than older learners in predictive studies whereas the opposite was true in interactional studies. The results suggest that language aptitude as measured via traditional aptitude tests is a set of cognitive abilities that were more implicated in initial stages of L2 development and conscious learning conditions. The findings are valuable to resolving some long-standing controversies surrounding language aptitude.

Striving for Complementarity Between Narrative and Meta-Analytic Reviews
Zhaohong Han
Applied Linguistics 2015 36: 409-415
This special issue is the first attempt to examine the complementarity of the meta-analytic and the traditional narrative review approaches and as such is very timely. Guided by a coherent framework provided by the editors, authors reported syntheses of the research on three topics—processing instruction (PI), the role of aptitude in (instructed) second language learning, and the teaching of pronunciation—as well as explicitly addressing how they went about their syntheses. Consequently, this special issue makes both a substantive and a methodological contribution to the field of applied linguistics in general and to SLA in particular.