This study examined the development of automaticity in processing L2 collocations, and the roles of L1 collocational knowledge and practice conditions in the development process. Korean learners of English were assigned to one of two practice conditions (practice in identical or varied contexts). The learning gains for word combinations with and without equivalent counterparts in the L1 (L1-only and L2-only collocations) were assessed using response times (RTs) and coefficients of variation (CV) from a phrasal decision task. The results demonstrated that the learners in both groups showed significantly improved collocation processing for both types of items in terms of speed (RT) and automaticity (CV) over time. The RT and CV analyses indicated that both groups’ improvements in collocation processing in the later stages of learning were associated with automatization. Interestingly, L1 collocational knowledge played a facilitative role in processing speed only in the early stages of learning. No reliable evidence for the differential effects of the two types of practice conditions on developing automaticity in collocation processing was found.

Since Gisela Granena’s influential work, LLAMA D v2, a sound recognition subtest of LLAMA aptitude tests, has been used as a measure of implicit learning aptitude in second language acquisition research. The validity of this test, however, is little known and the results of studies with this instrument have been somewhat inconsistent. In this study, we tested the hypothesis that researchers’ variable test instructions are the source of the inconsistent results. One hundred fourteen English monolinguals were randomly assigned to take LLAMA D v2 under one of three test instruction conditions. They also completed two implicit aptitude tests, three explicit aptitude tests, and a sound discrimination test. The results showed that, regardless of the type of test instructions, LLAMA D scores did not align with implicit aptitude test scores, indicating no clear evidence of the test being implicit. On the contrary, LLAMA D scores were negatively associated with scores on one implicit aptitude test, the Serial Reaction Time (SRT) task, but only in the condition where the instructions drew participants’ focal attention to the stimuli. This negative association was interpreted as focal attention working against learning in the SRT task. Implicit learning aptitude may be the degree to which one is able to process input without focal attention.

In this commentary, we summarize the findings of the seven included studies that examined implicit language aptitude from various perspectives and highlight issues to be resolved in the validation of this new construct in second language research. We start by providing an overview of the contributions of the studies. We then identify the lack of convergent validity of the measures of implicit aptitude reported in the included studies and problematize the equally varied nature of the measurement of implicit knowledge—the outcome variable of aptitude research—and related concepts. In particular, by drawing on empirical evidence and theoretical claims, we attempt to clarify the relationships between implicit and explicit knowledge, implicit and explicit learning, and implicit and explicit instruction. Next, we draw attention to the interactions reported by the included studies between aptitude and outcome measures and between aptitude and instruction type, emphasizing the value and importance of interactional research. We conclude by making recommendations for future research.

This article discusses the conceptualization, measurement, and validity of a recently emerged construct in the field of second language acquisition (SLA)—implicit language aptitude (alternatively “implicit aptitude”). Implicit aptitude is a set of cognitive abilities that enable learners to make unconscious computations of the distributional and transitional probabilities of linguistic input. Implicit aptitude is key to an accurate understanding of the cognitive foundation of language learning and contributes significantly to the advancement of SLA theory and pedagogy. The article starts by clarifying the concept and components of implicit aptitude, elaborating its role in SLA theories, identifying its attributes, and discussing its measurement. It then synthesizes the empirical evidence on its divergent, convergent, and predictive validity, which refers to whether it is distinct or separable from explicit aptitude, whether measures of implicit aptitude are correlated, and whether it is predictive of learning outcomes, respectively. Next, the article provides an overview of the seven empirical studies included in this special issue that examined implicit aptitude from various perspectives. The article concludes by identifying future directions.

Lexical tones are widely believed to be a formidable learning challenge for adult speakers of nontonal languages. While difficulties—as well as rapid improvements—are well documented for beginning second language (L2) learners, research with more advanced learners is needed to understand how tone perception difficulties impact word recognition once learners have a substantial vocabulary. The present study narrows in on difficulties suggested in previous work, which found a dissociation in advanced L2 learners between highly accurate tone identification and largely inaccurate lexical decision for tone words. We investigate a “best-case scenario” for advanced L2 tone word processing by testing performance in nearly ideal listening conditions—with words spoken clearly and in isolation. Under such conditions, do learners still have difficulty in lexical decision for tone words? If so, is it driven by the quality of lexical representations or by L2 processing routines? Advanced L2 and native Chinese listeners made lexical decisions while an electroencephalogram was recorded. Nonwords had a first syllable with either a vowel or tone that differed from that of a common disyllabic word. As a group, L2 learners performed less accurately when tones were manipulated than when vowels were manipulated. Subsequent analyses showed that this was the case even in the subset of items for which learners showed correct and confident tone identification in an offline written vocabulary test. Event-related potential results indicated N400 effects for both nonword conditions in L1, but only vowel N400 effects in L2, with tone responses intermediate between those of real words and vowel nonwords. These results are evidence of the persistent difficulty most L2 learners have in using tones for online word recognition, and indicate it is driven by a confluence of factors related to both L2 lexical representations and processing routines. We suggest that this tone nonword difficulty has real-world implications for learners: It may result in many toneless word representations in their mental lexicons, and is likely to affect the efficiency with which they can learn new tone words.

This study is the first to compare objective and subjective measures of explicit and implicit knowledge under learning from incidental exposure. An experiment was conducted, during which L1 English speakers were trained on a semiartificial language, Japlish. A measure of explicit knowledge and a recently proposed measure of implicit knowledge (i.e., an untimed auditory grammaticality judgment and a word-monitoring task) were applied to gauge the two types of knowledge at two testing sessions, and their results were compared with those of subjective measures of awareness. Results revealed clear discrepancies between the two measurement approaches in terms of their sensitivity. In particular, while the subjective measures varied in identifying explicit and implicit knowledge of various Japlish constructions, the objective measures indicated that most of the knowledge was explicit, and development of implicit knowledge (measured by the word-monitoring task) was minimal, only manifested in detecting a case-missing violation at the delayed posttest. The results are discussed with reference to the current literature on explicit and implicit learning and knowledge, and it is concluded that the criterion of (un)awareness might not be by itself sufficient to provide a full account of L2 knowledge developed under incidental conditions.

It is commonly believed that second language (L2) acquisition of lexical tones presents a major challenge for learners from nontonal language backgrounds. This belief is somewhat at odds with research that consistently shows beginning learners making quick gains through focused tone training, as well as research showing advanced learners achieving near-native performance in tone identification tasks. However, other long-term difficulties related to L2 tone perception may persist, given the additional demands of word recognition and the effects of context. In the current study, we used behavioral and event-related potential (ERP) experiments to test whether perception of Mandarin tones is difficult for advanced L2 learners in isolated syllables, disyllabic words in isolation, and disyllabic words in sentences. Stimuli were more naturalistic and challenging than in previous research. While L2 learners excelled at tone identification in isolated syllables, they performed with very low accuracy in rejecting disyllabic tonal nonwords in isolation and in sentences. We also report ERP data from critical mismatching words in sentences; while L2 listeners showed no significant differences in responses in any condition, trends were not inconsistent with the overall pattern in behavioral results of less sensitivity to tone mismatches than to semantic or segmental mismatches. We interpret these results as evidence that Mandarin tones are in fact difficult for advanced L2 learners. However, the difficulty is not due primarily to an inability to perceive tones phonetically, but instead is driven by the need to process tones lexically, especially in multisyllable words.

For several decades now, research on the acquisition of ASL and other signed languages has contributed to our understanding of language acquisition and of age effects in particular. A strong decline in learning capacity with age has been shown in numerous studies with ASL as L1, and the age range for this critical period phenomenon appears to be very similar to what has been observed in even more studies in L2 (for both spoken and signed languages). Mayberry and Kluender (Mayberry & Kluender) argue that the two phenomena are quite different, however, to such an extent that the concept of a critical period is not applicable to L2. Their two main arguments are that L2 learners are less affected by late acquisition than L1 learners and that some L2 studies have not shown the kind of discontinuity in the age-proficiency function that is predicted by the concept of a critical period. As space is very limited, I will limit my comments to these two issues.

Response time variability and its changes over time have been interpreted as indicative of levels of knowledge automatization. Predominantly, only declines in variability have been examined over the course of practice and growing second language proficiency. We discuss possible scenarios that may involve increasing, rather than declining variability, such as the establishment of new memory representations. We present repeated-measures lexical decision data on novel words encountered incidentally in a lexical decision task, which show increased variability as familiarity increases. Similar patterns were observed in our reanalyses of data from other novel word learning experiments with task demands different from ours: auditory presentation and a posttest after seven days (Brown & Gaskell, 2014), as well as picture-matching and production tests (Bartolotti & Marian, 2014). Jointly, these results suggest that when no prior representation of a word exists, increased variability may index learning during its initial stages.

This study examined the differential effects of systematic perception and production practice and the role of musical ability in learning Mandarin tone-words by native English-speaking adults in a training study. In this study, all participants (N = 38; 19 for each practice group) were first taught declarative knowledge of Mandarin tones and of the target words on the first day. They had to reach criterion performance on the test of vocabulary before they started to engage in either perception or production practice on the second day. Each participant went through three practice sessions on three separate days. Immediate posttests assessing learning outcomes in both perceptive and productive skills were administered on the last day. Musical tonal ability tests were administered to all participants and used as a covariate. The results showed that performance was far worse when participants were tested on the reverse skill than when they were tested on the practiced skill in terms of both error rates and reaction times, providing strong support for the skill-specificity hypothesis. Musical tonal ability was found to correlate with accuracy performance in both tone-word perception and production.

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.

The current exploratory study aimed at investigating the role of cognitive aptitudes in determining the effect of practice distribution on second language learning. The study investigated to what extent language-analytic ability and working-memory capacity predicted the acquisition of grammar under two learning conditions that differ in the interval between the two training sessions. Learners of Japanese as a second language were trained on an element of Japanese morphosyntax under either distributed practice (7-day interval) or massed practice (1-day interval). The results revealed that language-analytic ability was only related to performance after distributed practice, whereas working-memory capacity was only related to performance after massed practice. These Aptitude × Treatment interaction findings can help establish the learning processes operating under distributed/massed practice conditions.

For some, research in learning and teaching of a second language (L2) runs the risk of disintegrating into irreconcilable approaches to L2 learning and use. On the one side, we find researchers investigating linguistic-cognitive issues, often using quantitative research methods including inferential statistics; on the other side, we find researchers working on the basis of sociocultural or sociocognitive views, often using qualitative research methods including case studies and ethnography. Is there a gap in research in L2 learning and teaching? The present article developed from an invited colloquium at the 2013 meeting of the American Association for Applied Linguistics in Dallas, Texas. It comprises nine single-authored pieces, with an introduction and a conclusion by the coeditors. Our overarching goals are (a) to raise awareness of the limitations of addressing only the cognitive or only the social in research on L2 learning and teaching and (b) to explore ways of bridging and/or productively appreciating the cognitive-social gap in research. Collectively, the nine contributions advance the possibility that the approaches are not irreconcilable and that, in fact, cognitive researchers and social researchers will benefit by acknowledging insights and methods from one another.

To investigate potential causes of L2 performance deficits that correlate with age of onset, we use a computational model to explore the individual contributions of L1 entrenchment and aspects of memory development. Since development and L1 entrenchment almost invariably coincide, studying them independently is seldom possible in humans. To avoid this confound, we study neural network models that learn to solve gender assignment and agreement tasks in Spanish and French. We model the learner as a collection of recurrent cell assemblies that subserve working memory and are facilitated by trainable long-term connections. Varying the time-course over which assemblies and connections are added allows us to compare small, growing, child-like networks to fixed-size adult-like ones. Networks undergo variable-length exposure to L1 before L2 onset to control the amount of L1 entrenchment. This model, by allowing us independent control of both variables, lends us a novel glimpse of all sides of their interaction and affords a rare test of the less-is-more hypothesis. Network comparisons suggest that final L2 proficiency declines as L2 onset delays increase relative to L1, implicating an L1 entrenchment effect. However, aspects of memory development during learning play a key role in mitigating these impairments, lending support to less-is-more as a contributor to sensitive periods.

Few researchers would doubt that ultimate attainment in second language grammar is negatively correlated with age of acquisition, but considerable controversy remains about the nature of this relationship: the exact shape of the age-attainment function and its interpretation. This article presents two parallel studies with native speakers of Russian: one on the acquisition of English as a second language in North America (n = 76), and one on the acquisition of Hebrew as a second language in Israel (n = 64). Despite the very different nature of the languages being learned, the two studies show very similar results. When age at testing is partialed out, the data reveal a steep decline in the learning of grammar before age 18 in both groups, followed by an essentially horizontal slope until age 40. This is interpreted as evidence in favor of the critical period. Both groups show a significant correlation between ultimate attainment and verbal aptitude for the adult learners, but not for the early learners. This is interpreted as further evidence that the learning processes in childhood and adulthood not only yield different levels of proficiency but are also different in nature.