In the field of second language (L2) research, interest in applying meta-analytic techniques has gained momentum in recent years. Considering the potentially far-reaching impact of meta-analyses, they must adhere to rigorous methodological practices and a high level of transparency regarding decisions made throughout the meta-analytic process. This study empirically assessed the methodological and reporting practices of 224 L2 meta-analyses published across 99 journals. To conduct systematic coding, a comprehensive instrument was developed, comprising 39 items that each address a key aspect of meta-analytic methodology or reporting practice. The overall findings provided an overview of current practices, identifying both strengths and areas for improvement. Based on the findings, recommendations were offered for improving methodological rigor and transparency in L2 meta-analyses. Additionally, the comprehensive coding instrument developed in this study offers a valuable resource for the systematic evaluation of methodological and reporting practices in future L2 meta-analytic research.

The present study investigated how initial proficiency impacted development in adolescent learners’ L2 speaking. The study reports on a longitudinal study with dense measurements with twelve adolescent L2 English learners. The participants were tested every week throughout their first year of secondary school (30 datapoints). The participants’ learning trajectory was modeled using generalized additive mixed models (GAMMs). Results showed large differences in development between various lexical and syntactic measures and between individual learners. The learners’ initial proficiency had a significant impact on their development. Overall, more periods of growth were observed in lexical measures than in syntactic measures. In line with previous results, some stabilization was observed once learners reached a certain proficiency level, but this stabilization was dependent on task type. Closed tasks lead to a ceiling effect in some measures, whereas more open tasks give learners from various proficiency levels opportunities to demonstrate their L2 English speaking skills.

Screen-based reading has frequently been associated with lower comprehension than reading on paper, a phenomenon known as screen inferiority. Although cognitive capacity, linguistic knowledge, and digital usage vary across learners, it remains underexplored how individual-difference factors shape medium effects in second-language (L2) reading among adolescents. We investigated how reading on paper versus tablets affects L2 reading comprehension among 240 Korean eighth graders learning English and whether medium effects are moderated by working memory, L2 proficiency, and tablet experience. Participants completed comprehension tests under both conditions, along with a reading span task, a proficiency test, and a tablet-usage questionnaire. Results showed that participants performed worse on tablets than on paper; these gaps were larger among learners with higher spans and proficiency. In contrast, tablet experience did not interact with reading medium. These findings underscore the need for explicit instruction to support effective L2 reading on digital devices, even for high-performing learners.

Over the past decade, there has been growing use of mobile-assisted language learning (MALL) applications such as Duolingo. The effectiveness of MALL applications is thus of great interest among language acquisition researchers and practitioners. This study compared French language development among beginners in three learning conditions: Classroom-Only (n = 58), Duolingo-Only (n = 65), and Classroom + Duolingo (n = 60). The Classroom-Only group completed a standard first-semester curriculum, the Classroom + Duolingo group used Duolingo as supplemental material, and the Duolingo-Only group learned exclusively through the app. All participants completed pretests and posttests measuring overall proficiency, grammar, vocabulary, pragmatics (tu vs. vous), and communicative competence over a 16-week period. Linear mixed-effects models revealed that all three groups showed significant improvement across nearly all measures between pretest and posttest, with similar magnitudes of improvement. The only exception was in learning tu vs. vous (pragmatic competence), where the Classroom + Duolingo group showed larger gains than Classroom-Only and Duolingo-Only groups. Results suggest that both traditional classroom instruction and Duolingo are comparably effective for beginning French language learners. Results are discussed in light of mobile app-based language learning with the potential role of learner characteristics.

Natural phonetic variability such as talker differences facilitates second language (L2) word learning. Whether accent variability enhances the talker variability benefit, particularly in the learning of words that differ only in lexical tones, has not yet been examined despite its potential applied value for L2 tone language learning. Two groups of monolingual English speakers completed six training sessions on four minimal-tone quadrads of Mandarin monosyllabic pseudowords, produced either by 12 talkers from Beijing (single accent) or by four talkers each from Beijing, Yantai, and Guangzhou (multiple accents). Bayesian mixed-effects modeling revealed strong learning improvement across sessions in both conditions, but the multiple-accent group improved faster than the single-accent group. In addition, the multiple-accent group demonstrated superior generalization to new talkers with a familiar and an unfamiliar accent, suggesting that natural L2-Mandarin accent variability facilitates English learners’ access to abstract tone-word lexical representations, beyond the benefits of talker variability alone.

This study investigates whether adult learners can simultaneously acquire the sounds, words, and grammar of a novel language through cross-situational statistical learning (CSL). English-speaking participants were exposed to an artificial language with unfamiliar phonology and varying morphological salience. Results showed measurable acquisition of nouns and verbs, but limited learning of adjectives and case markers. Importantly, only participants in the high-salience condition showed sensitivity to morphosyntactic violations, suggesting that perceptual salience enhances awareness of grammatical structure. A word–picture matching task revealed that learners encoded phonolexical forms imprecisely: while clearly deviant items were rejected, minimally different lures were often accepted. Finally, individual differences in phonolexical precision were only weakly associated with phonetic discrimination ability. These findings demonstrate the power and limits of CSL in second-language learning and highlight the importance of perceptual cues for acquiring complex L2 structure.

This study investigated the effects of contextual diversity (CD) on second language incidental vocabulary learning. A total of 124 Japanese learners of English were allocated to a control group or 2 experimental groups, either a high contextual diversity (HCD) or a low contextual diversity (LCD) group. Participants in the HCD group encountered target words across three different texts that varied in genre and topic, while those in the LCD group read three different texts that shared the same genre and topic. Meaning recall and recognition tests were conducted at pretest, immediate posttest, and delayed posttest. Results showed that HCD outperformed LCD on meaning recognition at the delayed posttest. Moreover, learners with greater prior vocabulary knowledge tended to benefit more from contextually varied input, whereas such input may have adverse effects on learners with lower lexical proficiency. This study offers insights into the role of CD in incidental vocabulary acquisition and provides pedagogical implications for optimally incorporating input variability into L2 vocabulary instruction.

Bilinguals tend to have slower response times in picture naming than monolinguals in both their first and second languages. Naming speed interacts with item frequency, suggesting that the bilingual disadvantage may be due to less frequent exposure to each language. We measure response speed in a Picture Naming and a Picture-Word-Interference paradigm among 98 bilinguals and 83 monolinguals, looking for interactions between word frequency and frequency of use of both L1 and L2. We confirm previous findings that monolinguals outperform bilinguals, and that the bilingual disadvantage is stronger for low- than for high-frequency items. While immersed bilinguals seem to have an advantage in L2 naming over non-immersed speakers, self-reported use of either language does not affect naming in either language, and the L1 is not affected by the immersed vs. non-immersed distinction. We conclude that frequency remains an elusive factor in bilingual development, and particularly in L1 attrition.

Lexical acquisition often occurs through reading, yet little research has compared how cognates, false cognates, and noncognates are learned contextually through reading. To this end, we conducted a week-long pretest-training-posttest study with 54 adult Polish learners of English. During three sessions on consecutive days, participants read 45 short stories (170–317 words) containing 90 target keywords (30 cognates, 30 noncognates, 30 false cognates). We examined how word type, context informativeness, and number of keywords occurrences affected keyword learning. Additionally, participants were randomly assigned to a control or awareness-raising group, the latter trained to notice cross-linguistic similarities. Mixed-effects models showed learning of all word types at immediate posttest, with cognates being learned the most and false cognates the least. Higher context informativeness and more keyword occurrences improved learning for all keywords, but false cognates benefited the most from contextual clues. However, raising awareness of cross-linguistic similarity did not enhance contextual learning.

This study examined the impact of video-based synchronous computer-mediated communication (SvCMC) on engagement in collaborative pre-task planning and L2 content used in task performance. One hundred twenty-eight Hong Kong learners of English were assigned to either a face-to-face (FTF) group (n = 64) or an SvCMC group (n = 64), where they completed planning for a monologic task. Based on Philp and Duchesne’s multidimensional model, planning was analyzed for cognitive (negotiation of meaning, semantically engaged talk), social (affiliative responses) and emotional engagement (enjoyment, anxiety), and task performance was coded for L2 content. Results showed that FTF mode led to significantly lower anxiety, more semantically engaged talk, and more affiliative responses, as well as conceptually richer task performances. Use of planned content was predicted by L2 proficiency and semantically engaged talk and negatively predicted by anxiety. Our findings contribute to an understanding of engagement in SvCMC and FTF modes and their impact on L2 learning.

Second language (L2) pronunciation research has measured speech comprehensibility by asking listeners to assess L2 learners’ speaking performance with rating scales. While some studies have provided validity evidence for these rating scales, few studies have examined the extent to which those scales effectively distinguish among L2 speakers. To fill this gap, the present study examines the 9-point scale used in Saito et al. (2020: Annual Review of Applied Linguistics, 40, 9–25.) and the 100-point scale in Huensch and Nagle (2023: Studies in Second Language Acquisition, 45(2), 571–585.) from a Rasch measurement perspective and showcases post hoc score category collapsing as a potential countermeasure against suboptimal rating scale functioning. Findings suggested that different score categories represented the same ability level and were therefore interchangeable. Collapsing these score categories yielded shorter but more functional scales without compromising the psychometric qualities of the original scales. These findings suggest that researchers need to empirically refine their scale lengths rather than uncritically following their conventional measurement practices.

Measurement invariance (MI) ensures that a given measure holds the same conceptual meaning for individuals from different groups and across multiple measurement occasions. Structural invariance (SI) is a logical extension of MI that examines whether relationships between latent constructs (e.g., structural paths within the model) hold equally across groups. To examine the status quo of MI and SI in second-language (L2) research, we systematically investigated the extent to which primary studies adhered to best practices in invariance testing and reporting. A total of 4,272 full-text records were screened, and 113 articles (116 independent samples; 147,856 participants) were included. The sample was fully double-coded to ensure accuracy and reliability. The results indicated alarming inconsistencies in how key invariance steps were implemented and reported. We offer empirically grounded recommendations for (a) improving methodological rigor of invariance assessments in the field and (b) contributing to more equitable and interpretable comparisons in multilingual settings.

The present study compares several lexical diversity (LD) measures to determine which measure, or measures, best predict receptive lexico-grammatical ability in written L2 Spanish, and whether a composite LD score is better than any single measure. We analyzed 1,225 written responses with eight different LD measures: six popular measures, a composite score based on Principal Component Analysis (PCA) of those six measures, and the traditional TTR to be used as a baseline against which to compare the other measures. Other predictor variables included the age and gender of the writers, the age of first exposure to Spanish, the number of years studying Spanish, and study abroad participation. The results of a series of mixed-effect logistic regression models suggest that the composite LD measure is best, and that among the LD measures studied, two predicted lexico-grammatical ability nearly equally well. We conclude with the recommendation that L2 language researchers use multiple LD measures, including a composite measure based on PCA, rather than any single LD measure.