This article presents a theoretical review of and methodological guidelines for the study of two key notions in second language acquisition research, complexity and difficulty. The term "complexity" has gained considerable currency over the past decades and has taken on a wide range of meanings. We argue for a more restricted…

Studying Latin in secondary education is still widespread in Europe and believed to result in cognitive benefits, even beyond the linguistic domain. In this study we explored the relation between such study and later academic achievement in higher education (N = 1,898). First, we demonstrated that Latin students exhibit increased levels of study…

Researchers often make claims regarding the importance of predictor variables in multiple regression analysis by comparing standardized regression coefficients (standardized beta coefficients). This practice has been criticized as a misuse of multiple regression analysis. As a remedy, I highlight the use of dominance analysis and random forests, a…

Open research practices are relevant to all stages of research, from conceptualization through dissemination. Here, we discuss key facets of open research, highlighting its rationales, infrastructures, behaviors, and challenges. Part I conceptualizes open research and its rationales. Part II identifies challenges such as the speed and cost of open…

Does complexity make multilingualism special? Since there is no unequivocal notion of complexity on which researchers agree, several characteristics that have been considered crucial for complexity are brought to bear on multilingualism. While multilingualism is fairly complex in some senses, for instance, because it requires that many variables…

Recent years have seen an expansion in the research related to structural brain adaptations related to the acquisition and processing of additional languages. However, the accumulating evidence remains to a great extent inconsistent, with a large variety of cortical, subcortical, and cerebellar effects reported in various studies. Here we propose…

The last two decades have seen a significant amount of interest in bilingual language learning and processing. A number of computational models have also been developed to account for bilingualism, with varying degrees of success. In this article, we first briefly introduce the significance of computational approaches to bilingual language…

Second language acquisition (SLA) research offers valuable insight on how languages are learned and how they coexist and influence each other. Sign language learners offer unique perspectives on SLA, allowing researchers to test theories that are otherwise constrained by access to only one modality. Current literature on sign language learning…

This methods showcase article provides a detailed overview of a mixed-effects modeling analysis of corpus data on the use of "that" in object and subject complementation by native speakers of English compared to its use by German and Spanish learners of English.

Stern (1983) reminds us of the ethical reasons for doing second language (L2) research. That is, given the considerable human and financial investments that go into language education, the practical activities of teaching "should not exclusively rely on tradition, opinion, or trial-and-error but should be able to draw on rational enquiry,…

This review scrutinizes the evidence concerning the factors that affect the ease with which multilinguals learn additional languages. First, I focus on language learning experiences that could help multilinguals acquire new languages (e.g., consequences of exposure, use of prior knowledge, biliteracy). I then discuss how multilinguals manage…

Which theoretical and empirical insights can inform language-in-education research that advances equitable and high-quality learning at school? In this three-part article, I first draw from various sources to foreground the urgent need to counteract linguicism and epistemic injustices and to commit to more just and rigorous scientific practices in…

Multilingual research could offer a unique perspective on how the languages already acquired by a person affect the online processing of a new language. But it is currently difficult to assess this issue because theoretical accounts of multilingualism have focused on acquisition rather than processing and most empirical research to date has…

Using the lenses of bilingualism and social justice, I reflect on relevant conceptual and methodological issues encountered in the study of the linguistic development of heritage language speakers. Themes examined include the early but varying timing of heritage language learning; the surrounding linguistic environment, including the link between…

Frequentist methods have long dominated data analysis in quantitative second language (L2) research. Recently, however, several empirical fields have begun to embrace alternatives known as Bayesian methods. Using an open-source approach, we provide an applied, nontechnical rationale for Bayesian methods in L2 research. First, we compare the…