Recently there has been some debate about the appropriacy of different lexical units in pedagogy and research (e.g., Brown et al., 2020; Dang & Webb, 2016a; Kremmel, 2016; Laufer & Cobb, 2020; McLean, 2018; Nation, 2016; Nation & Webb, 2011; Vilkaitė-Lozdienė & Schmitt, 2020). The lexical unit (word types, lemmas, flemmas, word families) needs to be considered when developing wordlists, vocabulary tests, and vocabulary learning programs. It is also central to the lexical profiles of text and corpora, which indicate the vocabulary learning targets associated with understanding different types of discourse. Perhaps most importantly, the lexical unit of words found in vocabulary learning resources such as word lists and tests may affect their pedagogical value. The aim of this article is to highlight aspects of research and pedagogy that are affected by lexical units and describe issues that should be considered when operationalizing words in studies of vocabulary and learning resources.

We used event‑related potentials to investigate how markedness impacts person agreement in English‑speaking learners of L2‑Spanish. Markedness was examined by probing agreement with both first‑person (marked) and third‑person (unmarked) subjects. Agreement was manipulated by crossing first‑person subjects with third‑person verbs and vice versa. Native speakers showed a P600 for both errors, larger for “first‑person subject + third‑person verb” violations. This aligns with claims that, when the first element in the dependency is marked (first person), the parser generates stronger predictions regarding upcoming agreeing elements using feature activation. Twenty‑two upper‑intermediate/advanced learners elicited a P600 across both errors. Learners were equally accurate detecting both errors, but the P600 was marginally reduced for “first‑person subject + third‑person verb” violations, suggesting that learners overused unmarked forms (third person) online. However, this asymmetry mainly characterized lower‑proficiency learners. Results suggest that markedness impacts L2 agreement without constraining it, although learners are less likely to use marked features top‑down.

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.

The first goal of this study was to examine how individual differences in initial L2 proficiency help explain L2 grammar development in oral production during short-term immersion abroad. The second goal of the study was methodological, and evaluated challenges that can result from operationalizing learners’ initial L2 proficiency as pretest performance on outcome measures (as opposed to independent proficiency measures) in analyses of L2 change. L2 Spanish learners participating in summer study abroad completed an elicited imitation task and two oral production tasks. Production data were analyzed for changes in relevant grammatical complexity and accuracy dimensions. Results indicate that learners with higher initial L2 proficiency experience greater L2 grammar advancement from short-term immersion, and that pretest performance can be an unreliable operational estimate of initial proficiency when analyzing L2 gains. We discuss findings following cognitive accounts of SLA, and highlight methodological implications for further research in immersion contexts and beyond.

Meta-analytic reviews collect available empirical studies on a specified domain and calculate the average effect of a factor. Educators as well as researchers exploring a new domain of inquiry may rely on the conclusions from meta-analytic reviews rather than reading multiple primary studies. This article calls for caution in this regard because the outcome of a meta-analysis is determined by how effect sizes are calculated, how factors are defined, and how studies are selected for inclusion. Three recently published meta-analyses are reexamined to illustrate these issues. The first illustrates the risk of conflating effect sizes from studies with different design features; the second illustrates problems with delineating the variable of interest, with implications for cause-effect relations; and the third illustrates the challenge of determining the eligibility of candidate studies. Replication attempts yield outcomes that differ from the three original meta-analyses, suggesting also that conclusions drawn from meta-analyses need to be interpreted cautiously.

This study examines the associations between implicit and explicit language aptitude and the effects of the timing of corrective feedback (CF). A total of 112 seventh-grade EFL learners were assigned to three groups: Immediate CF, Delayed CF, and Task Only. The three groups underwent three treatment sessions during which they performed six focused communicative tasks eliciting the use of the English past tense. The Immediate and Delayed CF groups received CF treatments in the first and final sessions, respectively, and the Task Only group performed the communicative tasks without receiving any feedback. Treatment effects were measured through an untimed grammaticality judgment test and an elicited imitation test. Implicit language aptitude was operationalized as procedural memory and explicit language aptitude as working memory and declarative memory. Multiple regression analysis showed that procedural memory was significantly predictive of the effectiveness of Immediate CF, declarative memory was significantly associated with Delayed CF and Task Only, and working memory was a significant predictor of Immediate CF and Delayed CF. The results were interpreted by consulting the methodological features of the treatments and the mechanisms of the three cognitive abilities.

Spanish monolingual speakers often produce recipient (Pedro le da un lápiz a María) and nonrecipient constructions (Antonio le lava la camiseta a Carmen) doubled by a dative clitic. Second language speakers and heritage speakers usually avoid clitics. This study examined whether structural priming could effectively increase the production of clitics in monolingual speakers (N = 23), L2 speakers (N = 28), and heritage speakers (N = 24). Participants completed a baseline study that measured the use of clitics in a picture description task, followed by a priming treatment, an immediate posttest, and a posttest a week later. Results showed that priming increased clitic production for all groups, and that the increase was still significant a week later in L2 speakers and heritage speakers. These findings support the view that structural priming may implicate implicit language learning and considers its pedagogical implications.

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 investigates L2 comprehension of focus-to-accentuation mapping in English sentences with focus particle only by advanced learners of English whose L1 was either Cantonese or Dutch. Two experiments were conducted to examine (a) whether L2 learners could map accentuation to focus; and (b) whether they could perceive accentuation in English sentences. Results show that accentuation played little role in Cantonese learners’ comprehension of focus, whereas it affected how accurately and quickly Dutch learners and native controls comprehended focus. Dutch learners were even more efficient than native controls in comprehending focus-to-accentuation mapping. Furthermore, both L2 groups could successfully perceive accentuation in English sentences. These findings suggest that multiple interfaces might not be equally problematic for L2 learners with different L1s, and convergence at multiple interfaces in L2 is possible. The comprehension difficulty observed in Cantonese learners can be attributed to their less detailed representation of focus-to-accentuation mapping in L2.

While monolingual speakers can use contrastive pitch accents to predict upcoming referents, bilingual speakers do not always use this cue predictively in their L2. The current study examines the role of recent exposure for predictive processing in native German (L1) second language learners of English (L2). In Experiment 1, participants followed instructions to click on two successive objects, for example, Click on the red carrot/duck. Click on the green/GREEN carrot (where CAPS indicate a contrastive L + H* accent). Participants predicted a repeated noun following a L + H* accent in the L1, but not in the L2, where processing was delayed. Experiment 2 shows that after an exposure period with highly consistent prosodic cues, bilinguals engaged in predictive processing in both their L1 and L2. However, inconsistent prosodic cues showed different effects on bilinguals’ L1 and L2 predictive processing. The results are discussed in terms of exposure-based and resource-deficit models of processing.

This aptitude–treatment interaction study investigated the extent to which explicit and implicit cognitive abilities are differentially related to learning outcomes under two corrective feedback conditions. One hundred and thirteen intermediate English learners of Spanish were randomly assigned to an implicit feedback (recast), explicit feedback (explicit correction), or control group after completing tests from two aptitude batteries (High-Level Language Aptitude Battery [Hi-LAB] and LLAMA). Linguistic improvement on noun-adjective gender agreement and Differential Object Marking was assessed using grammaticality judgment and oral production tasks. Results showed that implicit but not explicit abilities were relevant for the acquisition of gender agreement under implicit feedback as measured by grammaticality judgments. In contrast, explicit but not implicit abilities were relevant for the acquisition of object marking under explicit feedback as measured by oral production. These results lent support to a double dissociation, but they also suggested higher-order interaction effects between the type of cognitive ability, outcome measure, and target structure.

Following calls for more modality-sensitive perspectives of SLA, this study investigated the extent to which (a) producing the second language (L2) in the oral modality impacts learner-generated noticing and L2 development of grammatical structures embedded in subsequent auditory input, and whether (b) engaging in L2 production and input processing in the written modality differentially contributes to learner noticing and L2 outcomes compared to the oral modality. Participants were beginner-level L2 Spanish learners assigned to one of three pedagogic task conditions (No-output, Speaking, Writing). Two target structures differing in their relative intrinsic salience were considered in the study. Learners’ noticing behaviors were gauged using stimulated recall protocols, and L2 grammar development was measured using pre-, post-, and delayed posttests of production and written and aural acceptability judgment. Results revealed that engaging in oral output promoted greater noticing and deeper analysis of auditory input as well as more robust L2 grammar development compared to no output. However, sustained linguistic gains on the lower-salience target structure were only observed among participants who engaged in output and input processing in the written modality.

Measures of syntactic complexity such as mean length of T-unit have been common measures of language proficiency in studies of second language acquisition. Despite the ubiquity and usefulness of such structure-based measures, they could be complemented with measures based on usage-based theories, which focus on the development of not just syntactic forms but also form-meaning pairs, called constructions (Ellis, 2002). Recent cross-sectional research (Kyle & Crossley, 2017) has indicated that indices related to usage-based characteristics of verb argument construction (VAC) use may be better indicators of writing proficiency than structure-based indices of syntactic complexity. However, because cross-sectional studies can only show general trends across proficiency benchmarks, it is important to test these findings in individuals over time (Lowie & Verspoor, 2019). Thus, this study investigates the developmental trajectories of second language learners of English across two academic years with regard to syntactic complexity and VAC sophistication.

Precise auditory perception at a subcortical level (neural representation and encoding of sound) has been suggested as a form of implicit L2 aptitude in naturalistic settings. Emerging evidence suggests that such implicit aptitude explains some variance in L2 speech perception and production among adult learners with different first language backgrounds and immersion experience. By examining 46 Chinese learners of English, the current study longitudinally investigated the extent to which explicit and implicit auditory processing ability could predict L2 segmental and prosody acquisition over a 5-month early immersion. According to the results, participants’ L2 gains were associated with more explicit and integrative auditory processing ability (remembering and reproducing music sequences), while the role of implicit, preconscious perception appeared to be negligible at the initial stage of postpubertal L2 speech learning.

This study investigated the potential of phonetic symbols and keywords as response labels for perceptual training of L2 sounds. Seventy-one Spanish learners of English were assigned to three groups: symbols, keywords, and control. Students in the symbols and keywords groups followed a 4-week High Variability Phonetic Training (HVPT) program based on identification tasks. The target aspects addressed were eight English vowels that tend to be problematic for Spanish EFL learners (/iː ɪ æ ʌ ɜː e ɒ ɔː/). Training stimuli consisted of consonant-vowel-consonant (CVC) nonwords featuring these vowels on a range of phonetic contexts. Overall, the results revealed significant differences between the perception gains made by the two experimental groups, which performed similarly, and the control group. Both experimental groups were able to transfer gains to untrained nonwords, and to untrained voices. Moreover, gains were maintained over time. Improvements were also made in real words, especially by the symbols group, although no significant differences were found between groups. The results suggest that both phonetic symbols and keywords are effective labels for perceptual training and the creation/consolidation of perceptual sound categories. The study offers further evidence of the effectiveness of HVPT for pronunciation training as well as implications for perceptual training studies and language teaching.