This paper investigates the question of whether the Wave Model of linguistic change can furnish a valid idealization for the patterning of variation in interlanguage systems and, thereby, a scale for the determination of their degree of naturalness. Using cross-sectional data from 162 French-speaking adult learners, the paper analyzes the variability in the evolution of the English possessive determiners HIS and HER. The main findings are as follows:

1. The Wave Model furnishes a valid idealization for acquisitional change.

2. The developmental continuum reveals that L2, acquisition appears to involve a greater scope of variability. Change may be initiated in a more marked environment at a point when the rule change process is not yet fully completed in the less marked environment. Nonetheless, the proportion of learners showing variable application of the mature rule in only one environment at a time as opposed to those with variable application in both is more than 2:1.

3. Less natural systems evidence rule blockage and/or compartmentalization of the marked environment; rule conflict between noncontiguous parts of the rule, and violation of markedness constraints.

4. Premature adoption of gender marking on the possessive determiners or, more generally, failure to approach the target language rule with an unmarked, initial hypothesis is one important source of unnaturalness in rule variability.

The data analysis leads up to a number of other issues in interlanguage research such as inter-learner variation, the ‘acquisition-learning’ distinction, and the relationship between the Simple Codes Hypothesis and unsuccessful L2, acquisition.

The present study investigates the prosody/pragmatics interface in TBLT by extending the traditional morphological focus-on-form to a focus on intonational forms, with Spanish declaratives and imperatives. Twenty-eight intermediate L2 Spanish learners were assigned to one of two conditions that differed in the type of focus-on-form present during the pre- and posttask phases of a focused, task-based intervention: focus on grammar (FOG) or focus on grammar + intonation (FOG + I). All participants were administered an oral discourse completion task in a pre- and a posttest that elicited Spanish imperatives and declaratives to measure gains. Results show that participants, regardless of condition, did not distinguish imperatives from declaratives using intonation in the pretest. However, participants in the FOG + I condition modified their pitch range and pitch accents in the posttest to signal a difference between imperatives and declaratives, though their use was different from the input provided by a native speaker instructor.

This article deals with the interlanguage of adult second language (L2) learners acquiring finiteness. Due to the inaccessibility of bound inflectional morphology, learners use free morphology to mark a syntactic relationship as well as person and number features separately from the thematic verb, expressed by a pattern like the man is go. Results from longitudinally collected production data of Turkish learners of Dutch are reported and present evidence for the claim that (a) verb movement and production of inflectional morphology develop separately in various developmental steps and (b) finite forms in nonfinite contexts (and vice versa) are by-products of this development. Moreover, all is-patterns in different Germanic languages can be explained by the application of minimalist theory of verb movement and recent views on morphology. Is-patterns that correspond neither to the first language nor to the L2—a poverty-of-the-stimulus problem—turn out to be possible in other languages of the world and are constrained by Universal Grammar.

The goal of this epilogue is to use the methodological contributions of the studies presented in this special issue as a starting point for suggestions about methodology in conducting future interaction research. As is the case in most developing fields, interaction research develops methods internally as it continually borrows and extends techniques used in other disciplines and revitalizes older techniques by adding new or different angles unique to interaction. Interaction researchers have also begun to forge relationships in new areas (e.g., by working with psychologists and developing working memory [WM] tests). This sort of cooperation is an important step in the drive to uncover more information about the relationship between interaction and learning. As several contributors to this special issue have noted, the most recent advances in methodology have been driven by questions about how interaction works (as opposed to whether it works). In turn, some of the methodological innovations discussed here will also ultimately allow new questions to be asked. Indeed, the relationship between questions (i.e., suggestions about what needs to be investigated next) and methods (i.e., plans for how to carry out such investigations) is particularly close in interaction research, which is a relatively new but vibrant and quickly developing area. Consequently, this epilogue considers both methods and questions conjointly, beginning with a discussion of methodological issues in the most recent theorizing about the interaction hypothesis.I am grateful to Helen Carpenter, Akiko Fujii, Susan M. Gass, Mika Hama, Jennifer Leeman, Kim McDonough, and Jenefer Philp for various kinds of help, including discussions of ideas and feedback, in relation to an earlier version of this paper, and to Amanda Edmonds and the other SSLA editorial staff members for their outstanding work and assistance with this Epilogue and the entire special issue. Any errors are, of course, my own.

This volume aims to rekindle interest in the question of whether insights from the study of second language (L2) acquisition can usefully be called on to provide explanations for pidgin and creole genesis, providing (mainly) creolist perspectives.1 Not surprisingly, the focus of several contributions is on transfer in pidginization, creolization, and L2 acquisition.

This study considers the role of L1 phonological influence in L2 English past tense morphology production by native speakers of Spanish, Mandarin, and Japanese. While these L1s share similar phonological restrictions on consonant cluster formation needed for English past tense morphology, differences arise in L1 syntax (only Mandarin lacks syntactic past) and L1 prosodic structure (only Japanese has English-equivalent structure). Aggregate analyses indicate that an L1 English control group outperforms all L2 groups in oral suppliance of past tense morphology. Results therefore reveal that having the syntactic feature for past in the L1 does not translate into targetlike performance and that L1 phonological restrictions alone cannot fully explain nontargetlike performance. Considering previous and the current data sets, we argue that evidence from production of L2 English past tense cannot be used to adjudicate between representational deficit approaches and full access approaches, contrary to what has been argued previously.

Understanding how language modality (i.e., signed vs. spoken) affects second language outcomes in hearing adults is important both theoretically and pedagogically, as it can determine the specificity of second language (L2) theory and inform how best to teach a language that uses a new modality. The present study investigated which cognitive-linguistic skills predict successful L2 sign language acquisition. A group (n = 25) of adult hearing L2 learners of American Sign Language underwent a cognitive-linguistic test battery before and after one semester of sign language instruction. A number of cognitive-linguistic measures of verbal memory, phonetic categorization skills, and vocabulary knowledge were examined to determine whether they predicted proficiency in a multiple linear regression analysis. Results indicated that English vocabulary knowledge and phonetic categorization skills predicted both vocabulary growth and self-rated proficiency at the end of one semester of instruction. Memory skills did not significantly predict either proficiency measures. These results highlight how linguistic skills in the first language (L1) directly predict L2 learning outcomes regardless of differences in L1 and L2 language modalities.

This paper presents a study that attributes verb serialization in the interlanguage of Vietnamese-speaking ESL learners to language transfer and, furthermore, puts forward the view that such transfer bears a resemblance to substrate influence in creoles with serial verb constructions (SVCs). In a task that elicited English causatives through pictures representing the causation of events, a subset of the Vietnamese-speaking participants in this study produced a number of serial-type constructions that reflected lexicosemantic aspects of causative SVCs in Vietnamese. Speakers of Hindi-Urdu, a nonserializing language used for comparative purposes, did not produce any equivalents. Additionally, serial-type constructions with second verbs (V2s) representing a result (e.g., cook butter melt) predominated at lower levels of lexical proficiency, whereas serials with make and a result (e.g., make broken) were more evenly distributed across proficiency levels. One inference based on the results is that certain serials are eliminated early in the acquisition process through positive evidence obtained via English input, whereas others continue to appear beyond the elementary level because of misleadingly similar constructions in the input. A comparison of the proficiency-based transfer of “cook butter melt” serials in this study and the inferred transfer of SVCs in creolization suggests that, whereas transfer processes in the two contexts are congruent in certain ways (often resulting from the exigencies of communication, limited access to the TL, and linguistic convergence), the processes diverge because of differences in target norms and input conditions. The latter two factors provide one explanation for why SVC-related transfer effects were limited to a subgroup of Vietnamese-speaking participants in this study.

This article investigates the learning of two syntactic structures in Italian—Pre-possessive Determiner Article (PPDA) and Differential Object Marking—that each pose specific learning difficulties for Spanish-speaking learners of Italian (SSLI), resulting from the asymmetrical relationship with corresponding structures in the learners’ L1 (Spanish). The article also examines to what extent these difficulties can be alleviated by means of a relatively implicit type of form-focused instruction (Textual Enhancement, or TE). SSLI tend to omit the article before the possessive determiner (e.g., *mia macchina) and overuse the Prepositional Accusative (PA, the Romance languages’ instance of Differential Object Marking) in canonical SVO sentences (e.g., *conosco a Marco). Although both structures pose learning difficulties to SSLI, the learning path that leads SSLI to acquire these two features is different: SSLI have to learn to add PPDA to their interlanguage and they have to unlearn PA, a property of their L1. Sixty-eight instructed SSLI were divided in two groups. Group A read five texts where the absence of PA was textually enhanced; group B read the same texts where the presence of PPDA was enhanced. The participants took a timed grammatical judgment test before, shortly after, and two months after the instructional treatment. The results show that the effects of the TE are different for PA and PPDA, which indicates that features to be unlearned are more difficult and require more explicit instructional intervention.

The development of the communicative approach to language teaching and language learning, started only a few years back with the pilot work done in several centers for research in applied linguistics and by the language project group of the Council of Europe, has now reached a stage where it can safely be said that the pace has been set, and that a return to a strict linguistic or structural approach is not likely to occur. This does not mean, though, that all is for the best in the best of all possible language teaching worlds: all the pedagogical issues raised by the new approach have not been solved, nor thoroughly thought out yet, and our current practice, still in its exploratory stage, is largely based on intuitions and rules of thumb.

This study explores the second language (L2) acquisition of a segment that exists in learners’ first language (L1) and in their L2 but that differs in its phonetic realization and allophonic patterning in the two languages. Specifically, this research tracks development in one aspect of the production of the alveolar lateral /l/ in the L2 Spanish of 85 native English speakers from various levels of study and compares L2 productions to those of native Spanish speakers as well as to learners’ L1 English. Additionally, laterals produced in specific contexts are compared to examine learners’ acquisition of L2 allophonic patterning, as Spanish contains a subset of the lateral allophones that exist in English. Results suggest development toward nativelike norms in the phonetic details of Spanish /l/ and in allophonic patterning. These findings have implications for existing theoretical accounts of L2 speech learning, which cannot adequately account for the learning situation examined.

Second language (L2) teachers may shy away from self-assessments because of warnings that students are not accurate self-assessors. This information stems from meta-analyses in which self-assessment scores on average did not correlate highly with proficiency test results. However, researchers mostly used Pearson correlations, when polyserial could be used. Furthermore, self-assessments today can be computer adaptive. With them, nonlinear statistics are needed to investigate their relationship with other measurements. We wondered, if we explored the relationship between self-assessment and proficiency test scores using more robust measurements (polyserial correlation, continuation-ratio modeling), would we find different results? We had 807 L2-Spanish learners take a computer-adaptive, L2-speaking self-assessment and the ACTFL Oral Proficiency Interview – computer (OPIc). The scores correlated at .61 (polyserial). Using continuation-ratio modeling, we found each unit of increase on the OPIc scale was associated with a 131% increase in the odds of passing the self-assessment thresholds. In other words, a student was more likely to move on to higher self-assessment subsections if they had a higher OPIc rating. We found computer-adaptive self-assessments appropriate for low-stakes L2-proficiency measurements, especially because they are cost-effective, make intuitive sense to learners, and promote learner agency.

In recent years research on language acquisition (both L1 and L2) has gradually turned away from the domain of pure description towards dealing with problems of explanation. Most students of language development feel that it is somewhat insufficient to merely state the linguistic regularities and verbal strategies that according to the available production data appear to govern processes of language learning; rather, it seems desirable that the regularities observable in the learner's verbal behavior over time be in some way explained. Frequently, the term explanation is—implicitly rather than explicitly—understood as an attempt to reduce the specific linguistic regularities found in language learning processes to a set of some more general (i.e. non-linguistic) principles that will not only control other learning tasks as well, but will also govern man's mental activities as such (Slobin 1973, Schlesinger 1977, Larsen-Freeman 1976, Bever 1970, Wong-Fillmore 1976). Among those mental domains which appear to provide principles general enough to be applicable to problems of language, learning cognition or rather cognitive development turned out to be the most promising. As a consequence, a large number of studies focused on the attempt to explain formal linguistic properties of language learning processes in terms of more general regularities in man's cognitive abilities as they develop (Seliger 1980, Gass 1980, Felix 1976, Sinclair-de-Zwart 1973, Meisel 1979, Clahsen 1979). In fact, the term explanation frequently means little more than reducing language acquisition to aspects of cognitive development.

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).

Complex Dynamic Systems Theory (CDST), an instantiation in applied linguistics of complexity epistemology that transcends disciplinary boundaries, has gained much traction and momentum over the last decade, finding expressions in a fast-growing number of empirical second language developmental studies. However, the literature, while rapidly expanding, has displayed much confusion, notably oscillating between invoking CDST as a metatheory and as an object theory. Then, too, the metaphorical genesis of CDST—the metaphorical adoption of complexity epistemology from physical sciences—has seemed to invite miscellaneous interpretations, rendering CDST an ostensibly all-in-one conceptual prism. This article explores the epistemology of CDST, tracing its ontology and examining its role in second language developmental research. This enables a more nuanced understanding of CDST, while at once surfacing critical issues and directions for future research, as it moves toward a pluralistic approach to investigating CDST as a potentially unique lens on second language development.

Although lexical diversity is often used as a measure of productive proficiency (e.g., as an aspect of lexical complexity) in SLA studies involving oral tasks, relatively little research has been conducted to support the reliability and/or validity of these indices in spoken contexts. Furthermore, SLA researchers commonly use indices of lexical diversity such as Root TTR (Guiraud’s index) and D (vocd-D and HD-D) that have been preliminarily shown to lack reliability in spoken L2 contexts and/or have been consistently shown to lack reliability in written L2 contexts. In this study, we empirically evaluate lexical diversity indices with respect to two aspects of reliability (text-length independence and across-task stability) and one aspect of validity (relationship with proficiency scores). The results indicated that neither Root TTR nor D is reliable across different text lengths. However, support for the reliability and validity of optimized versions of MATTR and MTLD was found.

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.