Second language learning outcomes are highly variable, due to a variety of factors, including individual differences, exposure conditions, and linguistic complexity. However, exactly how these factors interact to influence language learning is unknown. This article examines the relationship between these three variables in language learners.

Native English speakers were exposed to an artificial language containing three sentence patterns of varying linguistic complexity. They were randomly assigned to two groups—incidental and instructed—designed to promote the acquisition of implicit and explicit knowledge, respectively. Learning was assessed with a grammaticality judgment task, and subjective measures of awareness were used to measure whether exposure had resulted in implicit or explicit knowledge. Participants also completed cognitive tests.

Awareness measures demonstrated that learners in the incidental group relied more on implicit knowledge, whereas learners in the instructed group relied more on explicit knowledge. Overall, exposure condition was the most significant predictor of performance on the grammaticality judgment task, with learners in the instructed group outperforming those in the incidental group. Performance on a procedural learning task accounted for additional variance. When outcomes were analyzed according to linguistic complexity, exposure condition was the most significant predictor for two syntactic patterns, but it was not a predictor for the most complex sentence group; instead, procedural learning ability was.

This study investigates whether gestures can be used during recasts to enhance the saliency of a target structure (locative prepositions) and to lead to better production of the target structure. Forty-eight low-intermediate English as a second language (ESL) students partook in communicative activities during which they received either no feedback (control), verbal recasts only (R), or recasts plus gesture (RG), and a subset of participants completed a stimulated recall session. Then the pretest, immediate, and delayed posttest scores of grammar and oral production tests were used to analyze the linguistic development. The results showed that no one commented on recasts or locative prepositions during the stimulated recall session and that there were no significant changes in grammar test scores in all conditions; however, the R and RG conditions performed significantly better in the production test than the control in the immediate posttest. Furthermore, the RG condition maintained the development in the delayed posttest, whereas the R condition did not.

Previous studies have shown that reading is an important source of incidental second language (L2) vocabulary acquisition. However, we still do not have a clear picture of what happens when readers encounter unknown words. Combining offline (vocabulary tests) and online (eye-tracking) measures, the incidental acquisition of vocabulary knowledge from reading and the online reading of unknown lexical items were examined. L2 English learners read a story containing unknown items while their eye movements were recorded. After eight exposures, L2 readers recognized the form and the meaning of 86% and 75% of the target nonwords, respectively, whereas they recalled the meaning of 55% of the nonwords. After three to four encounters, nonwords were read significantly faster, and by eight encounters they were read in a similar manner to previously known real words. Results also showed a positive relationship between new vocabulary learning outcomes and online reading, with longer reading times associated with higher vocabulary recall test scores. The study was also conducted with first language (L1) readers to provide baseline data for comparison. Results confirmed the L2 findings while also indicating an interesting L1-L2 distinction in the rate rather than in the ultimate outcome of the acquisition process.

The current study reports on a meta-analysis of the relative effectiveness of interaction in synchronous computer-mediated communication (SCMC) and face-to-face (FTF) contexts. The primary studies included in the analysis were journal articles and dissertations completed between 1990 and 2012 (k = 14). Results demonstrate that interaction in SCMC and FTF had a significant impact on second language (L2) development, providing further support for previous research demonstrating the efficacy of interaction in both communication modes (e.g., Mackey & Goo, 2007; Pellettieri, 2000; Smith, 2004, 2005). There was also a small advantage for interaction in SCMC on measures of overall L2 learning outcomes, with additional analyses indicating a small advantage for SCMC interaction on productive and written measures and a small advantage for FTF interaction on receptive and oral learning outcomes. Interestingly, there were no significant differences between SCMC and FTF, suggesting the mode of communication has no statistically significant impact on the positive developmental benefits associated with interaction.

This article draws on an approach that conceptualizes L2 learning difficulty in terms of implicit and explicit knowledge. In a study with first language Mexican Spanish university-level learners (n = 30), their teachers (n = 11), and applied linguistics experts (n = 3), we investigated the relationship between (a) these groups’ difficulty judgements of 13 selected L2 English structures and (b) perceived learning difficulty and learners’ actual performance on measures of implicit and explicit knowledge. Our findings show that experts’ learning difficulty judgements did not lead to significant predictions, whereas the learners’ own difficulty rankings correlated significantly with their performance on the measure of explicit knowledge. Although correlations based on teachers’ difficulty rankings did not reach statistical significance, the judgements of this group were the only ones that showed trends toward successful prediction of learners’ performance on both the implicit and the explicit L2 measures. Thus the teachers exhibited a trend toward the best overall prediction ability.

Much pronunciation research critically relies upon listeners’ judgments of speech samples, but researchers have rarely examined the impact of methodological choices. In the current study, 30 German native listeners and 42 German L2 learners (L1 English) rated speech samples produced by English-German L2 learners along three continua: accentedness, fluency, and comprehensibility. The goal was to determine whether rating condition, that is, (a) whether each speech sample is rated along all three continua after it is heard once or (b) whether all speech samples are rated along one continuum before being rated along the next continuum, and continuum order (e.g., whether participants rate speech samples for accentedness before comprehensibility or fluency) have an effect on listeners’ ratings. Results indicate no significant overall effects of rating condition or continuum order, but there is evidence of rating condition effects by listener group. The results have implications for laboratory and classroom assessments of L2 speech.

This study investigates the influence of grammatical role and discourse-level cues on the interpretation of different pronominal forms in native speakers of French, native speakers of Turkish, and Turkish learners of French. In written questionnaires, we found that native speakers of French were influenced by discourse-level cues when interpreting ambiguous overt subject pronouns in French, whereas native speakers of Turkish were mainly influenced by a syntactic cue—subjecthood—when interpreting null subjects (pro) in Turkish translation equivalents. When interpreting implicit subjects of nonfinite dependent clauses (PRO), native speakers of both French and Turkish were influenced by subjecthood. Finally, Turkish learners of French were influenced by discourse-level cues in the interpretation of overt pronouns as well as PRO and showed no subject preference in either case. These results are in line with approaches to second language (L2) acquisition that stress the role of discourse-level principles in the processing and use of a L2 (Clahsen & Felser, 2006; Klein & Perdue, 1997).

A meta-analysis was conducted to examine the construct validity of language aptitude by synthesizing the existing research that has been accumulated over the past five decades. The study aimed to provide a thorough understanding of the construct by aggregating the data reported in the primary research on its correlations with other individual difference variables and with second language (L2) achievement. A total of 66 studies were retrieved that contributed effect sizes based on 109 unique samples and 13,035 foreign language learners. The results revealed that (1) aptitude was independent of other cognitive and affective factors: it was distinct from motivation, had a negative correlation with anxiety, and overlapped with, but was distinguishable from, intelligence; (2) executive working memory was more strongly associated with aptitude and aptitude components than phonological short-term memory; (3) aptitude measured using full-length tests was a strong predictor of general L2 proficiency, but it had low predictive validity for vocabulary learning and L2 writing; and (4) different aptitude components demonstrated differential predictive validity for different aspects of learning. The findings are useful for tackling a number of conundrums surrounding language aptitude and shed light on how to reconceptualize the construct and reorient the research.

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 in this issue. Finally, I make some suggestions for future research.