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…

Language proficiency is multi-componential in nature and, according to many SLA researchers and L2 practitioners, is best captured by the concepts of complexity, accuracy, and fluency (CAF). Two of the three studies reported in this paper adopted the Cognition Hypothesis (Robinson, 2003) as the means to address the question of whether increasing…

The present study carried out a bibliometric analysis of L2 eye-tracking research. VOSviewer, CiteSpace, and CitNetExplorer were used for the analysis. The data were 245 articles indexed by Social Sciences Citation Index (SSCI). The study identified the research topics, trends, promising research directions, influential authors and documents, and…

This article is a conceptual and methodological exploration of a new construct, task interactional difficulty, and of a possible approach to assessing task demands in general. After arguing for the use of 'task difficulty' instead of 'task complexity', the notion of task interactional difficulty is analyzed, first by reviewing previous SLA…

It is two decades since Master (1997) published a framework for second language (L2) article pedagogy, based on several years of research into the acquisition of the English article system. Among his recommendations were a focus on intermediate level learners and a simplification of the rules presented to language learners. Since then, substantial…

In this short article I try to present a taxonomy of sources of difficulty, in particular complexity. I emphasize how these factors interact with each other and with individual differences and treatments, before illustrating some of these interactions and the methodological issues involved in studying them with examples from the empirical studies…

Foreign-accented speech is generally harder to understand than native-accented speech. This difficulty is reduced for non-native listeners who share their first language with the non-native speaker. It is currently unclear, however, how non-native listeners deal with foreign-accented speech produced by speakers of a different language. We show…

This study tests the theoretical predictions regarding effects of increasing task complexity (Robinson, 2001a, 2001b, 2007, 2010; Robinson & Gilabert, 2007) for second language (L2) pronunciation. Specifically, we examine whether more complex tasks (a) lead to greater incidence of pronunciation-focused language-related episodes (LREs) and (b)…

Languages spoken in larger populations are relatively simple. A possible explanation for this is that languages with a greater number of speakers tend to also be those with higher proportions of non-native speakers, who may simplify language during learning. We assess this explanation for the negative correlation between population size and…

We test the interpretation of pronominal forms in L2 speakers of English whose L1 is Spanish. Previous research on learners of nonnull subject languages has shown conflicting results. The aim of the present study is to reconcile previous evidence and shed light on the factors that determine learners' difficulty to interpret pronominal forms in the…

We present a proof-of-concept study that sketches the use of compression algorithms to assess Kolmogorov complexity, which is a text-based, quantitative, holistic, and global measure of structural surface redundancy. Kolmogorov complexity has been used to explore cross-linguistic complexity variation in linguistic typology research, but we are the…

Although a growing number of second language acquisition (SLA) studies take linguistic complexity as a dependent variable, the term is still poorly defined and often used with different meanings, thus posing serious problems for research synthesis and knowledge accumulation. This article proposes a simple, coherent view of the construct, which is…

This study investigates semantic categorization of the meaning of placement verbs by Danish and Spanish native speakers and two groups of intermediate second language (L2) learners (Danish learners of L2 Spanish and Spanish learners of L2 Danish). Participants described 31 video clips picturing different types of placement events. Cluster analyses…

The phenomenon of regularization -- learners imposing systematicity on inconsistent variation in language input -- is complex. Studies show that children are more likely to regularize than adults, but adults will also regularize under certain circumstances. Exactly why we see the pattern of behaviour that we do is not well understood, however.…

In this article, we introduce a template of methodological considerations, termed "the dynamic ensemble," for scholars doing or evaluating empirical second language development (SLD) research within a complexity/dynamic systems theory (CDST) framework. Given that CDST principles have yielded significant insight into SLD and have become…