Second language acquisition researchers often face particular challenges when attempting to generalize study findings to the wider learner population. For example, language learners constitute a ...heterogeneous group, and it is not always clear how a study's findings may generalize to other individuals who may differ in terms of language background and proficiency, among many other factors. In this paper, we provide an overview of how mixed‐effects models can be used to help overcome these and other issues in the field of second language acquisition. We provide an overview of the benefits of mixed‐effects models and a practical example of how mixed‐effects analyses can be conducted. Mixed‐effects models provide second language researchers with a powerful statistical tool in the analysis of a variety of different types of data.
Although working memory (WM) figures centrally in many theories of second language (L2) proficiency development and processing, some have argued that the importance of WM is overstated (e.g., Juffs,
...Transactions of the Philological Society, 102
, 199–225,
2004
). Despite many studies over the past two decades, the literature lacks a quantitative synthesis of the extant results. In this article, we report a meta-analysis of data from 79 samples involving 3,707 participants providing 748 effect sizes. The results indicate that WM is positively associated with both L2 processing and proficiency outcomes, with an estimated population effect size (
ρ
) of .255. In additional analyses, we assessed whether the WM–criterion relationship was modulated by potential covariates identified in the literature search (i.e., participant characteristics, WM measure features, criterion measure factors, and publication status). The results of the covariate analyses indicated larger effect sizes for the executive control (vs. storage) component of WM, and for verbal (vs. nonverbal) measures of WM. Minimal publication bias was detected, suggesting that WM has a robust, positive relationship with L2 outcomes. We discuss the implications of these results for models of WM and theories of L2 processing and L2 proficiency development.
Adults are notoriously poor second-language (L2) learners. A context that enables successful L2 acquisition is language immersion. In this study, we investigated the effects of immersion learning for ...a group of university students studying abroad in Spain. Our interest was in the effect ofimmersion on the native language (LI), English. We tested the hypothesis that immersion benefits L2 learning as a result of attenuated influence of the L1. Participants were Englishspeaking learners of Spanish who were either immersed in Spanish while living in Spain or exposed to Spanish in the classroom only. Performance on both comprehension and production tasks showed that immersed learners outperformed their classroom counterparts with respect to L2 proficiency. However, the results also revealed that immersed learners had reduced LI access. The pattern of data is most consistent with the interpretation that the LI was inhibited while the learners were immersed.
This study investigated the role of domain-general inhibitory control in trilingual speech production. Taking an individual differences approach, we examined the relationship between performance on a ...non-linguistic measure of inhibitory control (the Simon task) and a multilingual language switching task for a group of fifty-six native English (L1) speakers learning French (L2) and Spanish (L3). Better inhibitory control was related to reduced switch costs, but only when switching into or out of the more dominant L1, where inhibitory control has been theorized to be most important (Green, 1998). The results provide evidence of a direct link between inhibitory control abilities and language switching capabilities, and suggest constraints on the conditions under which a domain-general inhibitory control mechanism supports language switching.
Few adult second language (L2) learners successfully attain high‐level proficiency. Although decades of research on beginning to intermediate stages of L2 learning have identified a number of ...predictors of the rate of acquisition, little research has examined factors relevant to predicting very high levels of L2 proficiency. The current study, conducted in the United States, was designed to examine potential cognitive predictors of successful learning to advanced proficiency levels. Participants were adults with varying degrees of success in L2 learning, including a critical group with high proficiency as indicated by standardized language proficiency tests and on‐the‐job language use. Results from a series of group discrimination analyses indicate that high‐level attainment was related to working memory (including phonological short‐term memory and task set switching), associative learning, and implicit learning. We consider the implications for the construct of high‐level language aptitude and identify future directions for aptitude research.
The role of executive functioning in second language (L2) aptitude remains unclear. Whereas some studies report a relationship between working memory (WM) and L2 learning, others have argued against ...this association. Similarly, being bilingual appears to benefit inhibitory control, and individual differences in inhibitory control are related to online L2 processing. The current longitudinal study examines whether these two components of executive functioning predict learning gains in an L2 classroom context using a pretest/posttest design. We assessed 25 university students in language courses, who completed measures of WM and inhibitory control. They also completed a proficiency measure at the beginning and end of a semester and reported their grade point average (GPA). WM was positively related to L2 proficiency and learning, but inhibitory control was not. These results support the notion that WM is an important component of L2 aptitude, particularly for predicting the early stages of L2 classroom learning.
Background/Aims: The epithelial sodium channel (ENaC) in cortical collecting duct (CCD) principal cells plays a critical role in regulating systemic blood pressure. We have previously shown that ...cholesterol (Cho) in the apical cell membrane regulates ENaC; however, the underlying mechanism remains unclear. Methods: Patch-clamp technique and confocal microscopy were used to evaluate ENaC activity and density. Results: Here we show that extraction of membrane Cho with methyl-β-cyclodextrin (MβCD) significantly reduced amiloride-sensitive current and ENaC single-channel activity. The effects were reproduced by inhibition of Cho synthesis in the cells with lovastatin. We have previously shown that phosphatidylinositol-4,5-bisphosphate (PIP2), an ENaC activator, is predominantly located in the microvilli, a specialized apical membrane domain. Here, our confocal microscopy data show that α-ENaC was co-localized with PIP2 in the microvilli and that Cho was also co-localized with PIP2 in the microvilli. Either extraction of Cho with MβCD or inhibition of Cho synthesis with lovastatin consistently reduced the levels of Cho, PIP2, and ENaC in the microvilli. Conclusions: Since PIP2 can directly stimulate ENaC and also affect ENaC trafficking, these data suggest that depletion of Cho reduces ENaC apical density and activity at least in part by decreasing PIP2 in the microvilli.
English learners (ELs) in K–12 schools must acquire English while simultaneously mastering content knowledge. Educational technology may support students’ learning through the affordance of ...individualized language practice. The current randomized controlled trial intervention study examined the effects of Rosetta Stone Foundations software on English learning among middle school ELs. The study took place in Grades 6 to 8 of an urban U.S. school district (N = 221). Predictors of interest included time of testing (pretest vs. posttest) and software usage, and covariates included grade level, sex, and attendance. Additionally, socioeconomic status and home language were accounted for due to sample homogeneity. Multilevel models indicated that treatment group students showed larger gains than control group students on oral/aural outcomes. These results indicate that the software intervention enables individualized practice that can produce proficiency-related gains over and above the typical classroom curriculum.
Many recent studies demonstrate that both languages are active when bilinguals and second language (L2) learners are reading, listening, or speaking one language only. The parallel activity of the ...two languages has been hypothesized to create competition that must be resolved. Models of bilingual lexical access have proposed an inhibitory control mechanism to effectively limit attention to the intended language (e.g., Green, 1998). Critically, other recent research suggests that a lifetime of experience as a bilingual negotiating the competition across the two languages confers a set of benefits to cognitive control processes more generally (e.g., Bialystok, Craik, Klein, & Viswanathan, 2004). However, few studies have examined the consequences of individual differences in inhibitory control for performance on language processing tasks. The goal of the present work was to determine whether there is a relation between enhanced executive function and performance for L2 learners and bilinguals on lexical comprehension and production tasks. Data were analyzed from two studies involving a range of language processing tasks, a working memory measure, and also the Simon task, a nonlinguistic measure of inhibitory control. The results demonstrate that greater working memory resources and enhanced inhibitory control are related to a reduction in cross-language activation in a sentence context word naming task and a picture naming task, respectively. Other factors that may be related to inhibitory control are identified. The implications of these results for models of bilingual lexical comprehension and production are discussed.
Studies of bilingual speech production suggest that different executive functions (EFs) contribute to the cognitive control of language production. However, no study has simultaneously examined the ...relationship between different EFs and language control during online speech production. The current study examined individual differences in three EFs (working memory updating, inhibitory control, and task-set switching) and their relationship with performance in a trilingual language-switching task for a group of forty-seven native English (L1) speakers learning French (L2) and Spanish (L3). Analyses indicate complex interactions between EFs and language switching: better inhibitory control was related to smaller L1 switch costs, whereas better working memory was related to larger L1 switch costs. Working memory was also related to larger L2 switch costs, but only when switching from L1. These results support theories of cognitive control that implicate both global and local control mechanisms, and suggest unique contributions of each EF to both global and local cognitive control during language switching. Finally, we discuss the implications for theories of multilingual language control.
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