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…

This article responds to calls for greater inclusivity in second language acquisition research and, more specifically, to calls to explore further the impact of first language literacy on second language oracy (e.g., Tarone et al., 2009). We conducted a partial replication of Foster and Skehan's (1996) influential study of task complexity,…

This study examined the relationship of linguistic complexity, captured using a set of lexical richness, syntactic complexity, and discoursal complexity indices, to second language (L2) learners' perception of text difficulty, captured using L2 raters' comparative judgment on text comprehensibility and reading speed. Testing materials were 180…

Frequency is often the only variable considered when researchers or teachers develop vocabulary materials for second language (L2) learners. However, researchers have also found that many other variables affect vocabulary acquisition. In this study, we explored the relationship between L2 vocabulary acquisition and a variety of lexical…

Large-scale learner corpora collected from online language learning platforms, such as the EF-Cambridge Open Language Database (EFCAMDAT), provide opportunities to analyze learner data at an unprecedented scale. However, interpreting the learner language in such corpora requires a precise understanding of tasks: How does the prompt and input of a…

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…

This study investigated whether task complexity influences second language (L2) writers' fluency, pausing, and revision behaviors and the cognitive processes underlying these behaviors; whether task complexity affects linguistic complexity of written output; and whether relationships between writing behaviors and linguistic complexity are…

This study investigated the effects of task complexity on child learners' second language (L2) gains, the relationship between aptitude and L2 development, and the extent to which task complexity influences this relationship when recasts are provided. Sixty child EFL learners were assigned to two experimental groups. During the treatment, one…

This chapter introduces three applications of Bayesian inference to common and novel issues in second language research. After a review of the critiques of conventional hypothesis testing, our focus centers on ways Bayesian inference can be used for dealing with missing data, for testing theory-driven substantive hypotheses without a default null…

Taking a psycholinguistic orientation within task-based language teaching scholarship, this study investigated the effects of mode (oral vs. written) and task complexity on second language (L2) performance. The participants were 78 Catalan/Spanish learners of English as a foreign language. Half of the participants performed the simple and complex…

It is generally accepted that second language (L2) acquisition becomes more difficult as one grows older and that success in adult L2 acquisition is highly variable. Nevertheless, humans in language contact situations have to cope with intergroup communication. This article examines the ways society has responded to this challenge. It describes…

The study reported in this paper investigated the relationship between components of aptitude and the fluency, lexical variety, syntactic complexity, and accuracy of performance in two types of written and spoken narrative tasks. We also addressed the question of how narrative performance varies in tasks of different cognitive complexity in the…

Text comprehension models in first and second language reading research posit that slow word recognition inhibits reading speed and decreases comprehension. To investigate the role of word recognition in reading, 2 experiments examined rereading benefits in participants' first and second languages using scrambled and normal versions of English and…

Learners' ability to recognize linguistic contrasts in American Sign Language (ASL) was investigated using a paired-comparison discrimination task. Minimal pairs containing contrasts in five linguistic categories (i.e., the formational parameters of movement, handshape, orientation, and location in ASL phonology, and a category comprised of…

The present study adopted a cognitive linguistic framework--Talmy's (1985, 1991, 2000) typological classification of motion events--to investigate how second-language (L2) Chinese learners come to express motion events in a targetlike manner. Fifty-five U.S. university students and 20 native speakers of Chinese participated in the study. A…