Several multilingual language production models assume that language control is instigated by conflict monitoring. In turn, conflict adaptation, a control process which makes it easier to resolve interference if previously a high-interference context was detected, should also occur during multilingual production, as it is triggered by conflict monitoring. Because no evidence has been provided for conflict adaptation in the multilingual production literature, we set out to investigate this process using the n-3 effect. Our study showed that the n-3 effect can be observed during multilingual production, and thus provides evidence for conflict adaptation during multilingual production.

Socio-cognitive research on bilinguals points to a moral foreign-language effect (MFLE), with more utilitarian choices (e.g., sacrificing someone to save more people) for moral dilemmas presented in the second language (L2) relative to the first language. Yet, inconsistent results highlight the influence of subject-level variables, including a critical underexplored factor: L2 proficiency (L2p). Here we provide a systematic review of 57 bilingualism studies on moral dilemmas, showing that L2p rarely modulates responses to impersonal dilemmas, but it does impact personal dilemmas (with MFLEs proving consistent at intermediate L2p levels but unsystematic at high L2p levels). We propose an empirico-theoretical framework to conceptualize such patterns, highlighting the impact of L2p on four affective mediating factors: mental imagery, inhibitory control, prosocial behavior and numerical processing. Finally, we outline core challenges for the field. These insights open new avenues at the crossing of bilingualism and social cognition research.

The five papers in this issue cover a range of perspectives on the acquisition and use of the Spanish copulas ser and estar in a variety of contexts, including language contact, bilingual language acquisition, and classroom second language learning. The fact that these papers cite work in this area as far back as the early part of the 20th century with each subsequent decade being represented suggests the continual importance and complexity of the distinction between the two copular forms and shows how this complexity is played out in acquisition and bilingual use. Over the past century different perspectives have been taken on this multifaceted issue with linguistic explanations and the role of the native language being primary. In this epilogue, we focus on some of these same issues, but expand our commentary to include the new dimensions represented in this collection of papers: (i) context of learning (input), (ii) prior knowledge as represented by other language(s) known, (iii) item-learning and lexical development, and (iv) innovations in methodology.

The present study aimed to explore the lexical processing abilities of bilingual school-aged children compared to their monolingual peers. Therefore, word form processing tasks (auditory lexical decision, rapid naming, rhyming), as well as traditional vocabulary tasks (word-picture matching and picture naming), were conducted in a cross-sectional design in a sample of 163 German monolingual and 39 bilingual primary school children (6-9 years), speaking German and another language. Regression analyses revealed that age, gender, and vocabulary size, but not bilingualism have an impact on performance in word form processing tasks. Group comparisons after propensity matching on age, gender, and vocabulary size revealed no significant group differences between monolingual and bilingual children in word form processing tasks. After the sample was divided into two age groups, bilingual children showed an initial weakness at ages 6 to 7 that seems to be overcome during primary school age.

From the beginning of this century fascinating work has been carried out on the simultaneous acquisition of two languages from birth in the form of diary studies for example, that by Ronjat (1913). Many aspects of monolingual language acquisition have been studied in the same way, whereby researchers generally observed their own children, for example, Stern and Stern (1928). The modern research strategy is to audiotape or videotape the speech of young children at fixed intervals. Of course, a quantitative analysis can be carried out for both diary studies and more recent types of longitudinal study. However, researchers such as Ronjat (1913) do not provide us with exact quantitative results. Notwithstanding, these studies deserve to be taken seriously and I think it is possible to interpret some of the observations they contain as good and “reliable” evidence and compare these with results from modern longitudinal studies, where exact quantification is an important issue. I therefore think that the quantitative results of my review of existing studies on the acquisition of German subordinate clauses in bilingual children can be taken seriously, although I agree with François Grosjean and Elizabeth Lanza, who object that the quantitative differences between monolingual and bilingual children's errors are perhaps artefacts of the setting in which the children have been recorded. That I considered diary studies as well disappointed one commentator, Annick De Houwer, who would have preferred a comparison of modern studies only.

Semantic feature-based treatments (SFTs) are effective rehabilitation strategies for word retrieval deficits in bilinguals with aphasia (BWA). However, few studies have prospectively evaluated the effects of key parameters of these interventions on treatment outcomes. This study examined the influence of intervention-level (i.e., treatment language and treatment sessions), individual-level (baseline naming severity and age), and stimulus-level (i.e., lexical frequency, phonological length, and phonological neighborhood density) factors on naming improvement in a treated and untreated language for 34 Spanish–English BWA who completed 40 hours of SFT. Results revealed significant improvement over time in both languages. In the treated language, individuals who received therapy in their L1 improved more. Additionally, higher pre-treatment naming scores predicted greater response to treatment. Finally, a frequency effect on baseline naming accuracy and phonological effects on accuracy over time were associated with differential treatment gains. These findings indicate that multilevel factors are influential predictors of bilingual treatment outcomes.

Emotional experiences are often dulled in one's second language. We tested whether emotion concepts are more strongly associated with first language (L1) than second language (L2) emotion words. Participants (140 L1-Swedish–L2-English bilinguals) saw a facial expression of an emotion (cue) followed by a target, which could either be another facial expression, an L1 emotion word, or an L2 emotion word. Participants indicated whether the cue and target represented the same or different emotions as fast as possible. Participants were faster and more accurate in both the L1 and L2 word conditions compared to the face condition. However, no significant differences emerged between the L1 and L2 word conditions, suggesting that emotion concepts are not more strongly associated with L1 than L2 emotion words. These results replicate prior research showing that L1 emotion words speed facial emotion perception and provide initial evidence that words (not only first language words) shape emotion perception.

We investigated cross-modal influences between speech and sign in hearing bimodal bilinguals, proficient in a spoken and a sign language, and its consequences on visual attention during message preparation using eye-tracking. We focused on spatial expressions in which sign languages, unlike spoken languages, have a modality-driven preference to mention grounds (big objects) prior to figures (smaller objects). We compared hearing bimodal bilinguals’ spatial expressions and visual attention in Dutch and Dutch Sign Language (N = 18) to those of their hearing non-signing (N = 20) and deaf signing peers (N = 18). In speech, hearing bimodal bilinguals expressed more ground-first descriptions and fixated grounds more than hearing non-signers, showing influence from sign. In sign, they used as many ground-first descriptions as deaf signers and fixated grounds equally often, demonstrating no influence from speech. Cross-linguistic influence of word order preference and visual attention in hearing bimodal bilinguals appears to be one-directional modulated by modality-driven differences.

Does a concurrent verbal working memory (WM) load constrain cross-linguistic activation? In a visual world study, participants listened to Hindi (L1) or English (L2) spoken words and viewed a display containing the phonological cohort of the translation equivalent (TE cohort) of the spoken word and 3 distractors. Experiment 1 was administered without a load. Participants then maintained two or four letters (Experiment 2) or two, six or eight letters (Experiment 3) in WM and were tested on backward sequence recognition after the visual world display. Greater looks towards TE cohorts were observed in both the language directions in Experiment 1. With a load, TE cohort activation was inhibited in the L2 – L1 direction and observed only in the early stages after word onset in the L1 – L2 direction suggesting a critical role of language direction. These results indicate that cross-linguistic activation as seen through eye movements depends on cognitive resources such as WM.

The paper to which this commentary responds (Goldrick, Putnam & Schwarz, 2016) represents a big step forward in a field which was showing signs of stasis – the study of the grammatical properties of intra-sentential code-switching or code-mixing – and this for two reasons. First of all, it explicitly links the insights from the grammatical study of code-mixing to the rich array of results from psycholinguistic research in the domain of bilingual language processing, making use of the Gradient Symbolic Computation framework (GSC; Smolensky, Goldrick & Mathis, 2014). Second, it provides a set of tools to handle problems in the domain of code-mixing having to do with simultaneous representations in the domain of bilingual complexes.

This study investigated whether L1-Korean L2-English speakers could use (in)definiteness to predict unmentioned (non-)unique referents. In previous studies on the topic, methodological considerations made it difficult to separate the effects of grammar from the effects of non-linguistic knowledge. We used a visual world paradigm eye-tracking task to resolve such issues and designed stimuli that focused only on (in)definiteness. Participants’ eye movements were recorded as they heard “Click on the/a blue circle.” L1 and advanced L2 speakers used definiteness information to predict unique referents before the critical noun (circle) was heard while indefinite articles were not utilized to the same extent. Intermediate L2 speakers relied heavily on color words, not articles, to locate a referent. The results imply that predicting a referent solely based on definiteness (without real-world knowledge) requires substantial advancement in L2 development, and indefinite articles do not predict non-unique referents as clearly as definite articles predict unique referents.

Compared with the wealth of investigations on monolingual language acquisition, research on early bilingualism still has some catching up to do. Papers such as the one by Natascha Müller show us what may be gained if results from both areas are integrated within one theoretical framework, in this case current generative theory.

In their keynote article, Dijkstra, Wahl, Buytenhuijs, van Halem, Al-jibouri, de Korte, and Rekké (2018) introduce the Multilink model representing an integrated bi/multilingual lexicon. This proposal builds upon both previous and recent research on an integrated cognitive architecture underlying the language faculty (for a summary, see e.g., Putnam, Carlson & Reitter, 2018). In our view, the adjustments proposed by the authors are an improvement on previous instantiations of similar models such as those discussed in the present article. In our remarks we explicate how the Multilink model may be further enhanced, by making any appeal to language-specific nodes or representations epiphenomenal. To achieve this, we propose a novel approach to representing language membership as the result of gradient emergent principles that builds upon the integrated lexicon underlying the Multilink model.

Bilingualism is an experience that varies across a continuum and can change across the lifespan. Psychometric research is an underexplored avenue with the potential to further our understanding of the mechanisms and traits underlying bilingual experiences. Here, we developed and validated a social network questionnaire to measure sociolinguistic features in 212 individuals via personal social network. Confirmatory factor analysis examined the measurement structure of the variables. Compared to a one-factor model, the best fitting model was a two-factor model in which the language experience of the individual (i.e., ego) and the language experience of the individual's network (i.e., alters) were correlated latent factors under which aspects of the bilingual experience loaded. Additional analyses revealed other potential ways to examine the data in future analyses. These results provide the first measurement model of bilingual experiences, and provide support for theoretical accounts suggesting differential neuropsychological outcomes based on individual bilingual variability. The results also support the use of social network tools to capture differences in bilingualism.

Pieter Muysken's article on modeling and interpreting language contact phenomena constitutes an important contribution.The approach chosen is a top–down one, building on the author's extensive knowledge of all matters relating to language contact. The paper aims at integrating a wide range of factors and levels of social, cognitive, and linguistic accounts, incorporating findings on bilingual individuals in the same way as on language systems in contact and bilingual speech communities. It enables the reader to place seemingly disparate phenomena in a wider perspective and to relate quite divergent manifestations of language contact to one another in a principled way. In accordance with its ambitious goal, the paper proposes a high level of generalization, or abstraction.