Second Language Acquisition

Self-report questionnaires on individual differences (IDs) are central to second language acquisition (SLA) research, yet the qualitative procedures that generate their item pools remain largely unexamined. Drawing on argument-based validation theory and cross-disciplinary measurement guidelines, this study offers the first systematic methodological synthesis of how that formative phase is reported. We reviewed 85 peer-reviewed SLA studies published between 1983 and 2025 that developed or substantially revised an ID scale, coding each along four dimensions: transparency, theoretical grounding, methodological rigor, and content-validity evidence. Four research questions examined how qualitative item development was documented, which methods and frameworks were employed, how item inclusion was justified, and how content validity was assessed. Results expose a pervasive reporting gap: Only 25% of studies described any qualitative data collection, 16% referenced an explicit theoretical framework, 2% linked draft items to participant quotations, and only one study reported a numerical content validity index. Details on coder agreement, reflexivity, and response-process evidence were nearly absent. These gaps threaten construct representativeness, invite cultural bias, and undermine validation claims. We translate our findings into a seven-section reporting checklist for the qualitative phase, with implications for editorial policy, doctoral training, and future meta-analyses.

In second language (L2) acquisition research, understanding how learners process words across languages is crucial, with the translation priming paradigm consistently revealing that an L2 word can be processed significantly faster after a brief presentation of its translation equivalent in one’s first language (L1) but not vice versa. This study attempted to replicate Chen et al.’s (2014) investigation of translation priming asymmetry with Chinese-English bilinguals in an online environment using the Naodao crowdsourcing platform. We conducted three masked priming lexical decision experiments: two testing L1-to-L2 and L2-to-L1 priming with a 50-ms prime duration, and one examining L2-to-L1 priming with an extended 250-ms prime duration. Results showed that the classic asymmetry pattern was not fully reproducible in this online setting at 50-ms prime duration, with null effects in both directions. However, significant priming effects emerged with the extended prime presentation in the L2-to-L1 direction. These findings suggest that online implementation of timing-sensitive paradigms may require methodological adaptations.

In the past decade, researchers have been increasingly interested in understanding the process of language learning, in addition to the effect of instructional interventions on L2 performance gains (i.e., learning products). One goal of such investigations is to reveal the interplay between learning conditions, processes, and outcomes where, for example, certain conditions can promote attention to the learning targets, which in turn facilitates learning. However, the statistical modeling approach taken often does not align with the conceptualization of the complex relationships between these variables. Thus, in this paper, we introduce mediation analysis to SLA research. We offer a step-by-step, contextualized tutorial on the practical application of mediation analysis in three different research scenarios, each addressing a different research design using either simulated or open-source datasets. Our overall goal is to promote the use of statistical techniques that are consistent with the theorization of language learning processes as mediators.