Abundant research has indicated fluency features as meaningful predictors of second language proficiency. However, the extent to which different fluency dimensions and features can predict proficiency remains underexplored. This meta-analysis employed a multilevel modeling approach to synthesize fluency-proficiency relationships from 71 empirical…

Eye tracking has taken hold in second language acquisition (SLA) and bilingualism as a valuable technique for researching cognitive processes, yet a comprehensive picture of reporting practices is still lacking. Our systematic review addressed this gap. We synthesized 145 empirical eye-tracking studies, coding for 58 reporting features and…

Second language (L2) viewing with captions (i.e., L2 on-screen text) is now a proliferating as well as promising area of L2 acquisition research. The goal of the present meta-analysis was to examine (a) the relationship between captioned viewing and incidental vocabulary learning and (b) what variables related to learners, treatment, methodology,…

We present a review of second language researchers' use of cluster analysis, an advanced statistical method still uncommon but increasingly used to identify groups or patterns in a dataset and to examine group differences. After describing key methodological considerations in conducting cluster analysis, we present a methodological synthesis of 65…

Research on anxiety and motivation in second language (L2) learning is proliferating. However, these two individual differences are commonly measured by self-report questionnaires, the psychometric properties of which have been questioned. Building on previous works on study quality, this methodological synthesis systematically describes and…

This study examined the crosslinguistic sharing of morphological awareness (MA) in biliteracy development. The analysis included 34 correlational studies with 41 independent samples (N = 4,104). Correlational coefficients were meta-analyzed, yielding four main findings: (a) the correlation between first language (L1) and second language (L2) MA…

The involvement load hypothesis (ILH) was designed to predict the effectiveness of instructional tasks for incidental L2 vocabulary learning. In this meta-analysis we examined 398 effect sizes from 42 empirical studies (N = 4,628) to explore (a) the overall predictive ability of the ILH, (b) the relative effects of different components of the ILH…

We propose a new framework for conceptualizing measures of instructed second language (L2) pronunciation performance according to three sets of parameters: (a) the constructs (focused on global vs. specific aspects of pronunciation), (b) the scoring method (human raters vs. acoustic analyses), and (c) the type of knowledge elicited (controlled vs.…

Despite its critical role for the development of the field, little is known about replication in second language (L2) research. To better understand replication practice, we first provide a narrative review of challenges related to replication, drawing on recent developments in psychology. This discussion frames and motivates a systematic review,…

This meta-analysis aimed to clarify the complex relationship between repetition and second language (L2) incidental vocabulary learning by meta-analyzing primary studies reporting correlation coefficients between the number of encounters and vocabulary learning. We synthesized and quantitatively analyzed 45 effect sizes from 26 studies (N = 1,918)…

We meta-analyzed the effectiveness of incidental second language word learning from spoken input. Our sample contained 105 effect sizes from 32 primary studies employing meaning-focused word-learning activities with 1,964 participants with typical cognitive functioning. The random-effects meta-analysis yielded a mean effect size of g = 1.05,…

Research synthesis and meta-analysis provide a pathway to bring together findings in a given domain with greater systematicity, objectivity, and transparency than traditional reviews. The same techniques and corresponding benefits can be and have been applied to examine methodological practices in second language (L2) research (e.g., Plonsky,…

Idealization plays a fundamental role in scientific inquiry. This article examines the case for maintaining the claim that the second language acquisition (SLA) of grammatical structures such as negation manifests identifiable stages of acquisition. It proposes that, while research has demonstrated the need for de-idealization, there is no need to…

This study applied systematic meta-analytic procedures to summarize findings from experimental and quasi-experimental investigations into the effectiveness of using the tools and techniques of corpus linguistics for second language learning or use, here referred to as data-driven learning (DDL). Analysis of 64 separate studies representing 88…

In bilinguals and second language learners, the native (L1) and nonnative (L2) languages coexist and interact. The L1 influences L2 production via forward transfer, as is seen with foreign accents. However, language transfer is bidirectional: even brief experience with an L2 can affect L1 production, via backward transfer. Here, we review the…