Are simultaneous interpreters subject to the central processing bottleneck, which can postpone the reaction time and impair the performance of another concurrent task, during word production? Moreover, is there any difference between interpreters, bilinguals and monolinguals in the word production bottleneck? In this study, professional simultaneous interpreters, proficient bilinguals and monolinguals performed a dual task consisting of a picture naming task in sentence context (Task 1) and a pitch tone discrimination task (Task 2). The results show that interpreters are also subject to the central processing bottleneck during word production, and there is no significant difference between the three groups in the duration of the word production bottleneck. Unexpected differences in performance were found between English–Asian language and English–European language pairs within the interpreter group, but not within the bilingual group, showing that European-language interpreters were as fast as monolinguals in lexical access, and faster than Asian-language interpreters and bilinguals.

How are the two lexicons of a bilingual represented and how do they interact during language processing? These questions are central to bilingualism and have been the topics of a large number of studies. Dijkstra, Wahl, Buytenhuijs, van Halem, Al-jibouri, De Korte & Rekke (in press) put forward a model that tries to capture people's behavior in several tasks mostly involving reading, with the exception of word translation. A praise-worthy feature of the model is that it is computationally implemented following a local-connectionist architecture. The model is then used to quantitatively account for reaction time patterns on various tasks, with considerable success.

We used eye movement measures of paragraph reading to examine whether two consequences of bilingualism, namely, reduced lexical entrenchment (i.e., reduced lexical quality and accessibility arising from less absolute language experience) and cross-language activation (i.e., simultaneous co-activation of target- and non-target-language lexical representations) interact during word processing in bilingual younger and older adults. Specifically, we focused on the interaction between word frequency (a predictor of lexical entrenchment) and cross-language neighborhood density (a predictor of cross-language activation) during first- and second-language reading. Across both languages and both age groups, greater cross-language (and within-language) neighborhood density facilitated word processing, indexed by smaller word frequency effects. Moreover, word frequency effects and, to a lesser extent, cross-language neighborhood density effects were larger in older versus younger adults, potentially reflecting age-related changes in lexical accessibility and cognitive control. Thus, lexical entrenchment and cross-language activation multiplicatively influence bilingual word processing across the adult lifespan.

A claim fundamental to the revised hierarchical model (Kroll & Stewart, 1994) was that concepts did not mediate backward translation, based on their findings of a category interference effect in forward translation in relatively fluent bilinguals but no category effect in backward translation. This study hypothesized that there was a category facilitation effect in L2-to-concept, which counterbalanced the category interference effect in concept-to-L1, resulting in an overall L2-to-L1 null category effect.

In a novel English word-pair semantic comparison task, participants were presented with a sequence of English word-pairs, and judged which word's real-world referent was bigger in size. Results found a significant category facilitation effect in both L2-to-concept for young Chinese adults and L1-to-concept for young English adults when increasing the number of trials. The findings help explain why Kroll and Stewart's finding of an overall L2-to-L1 null category effect cannot be evidence against concept mediation in backward translation.

Noticing the hole (NTH) occurs when speakers want to say something, but realise they do not know the right word(s). Such awareness of lacking knowledge supposedly facilitates the acquisition of the unknown word(s) from later input (Swain, 1993). We tested this claim by experimentally inducing NTH in a second language (L2) for some participants (experimental), but not others (control). Then, in a price comparison game, all participants were exposed to spoken L2 input containing the to-be-learned words. They were unaware of taking part in an L2 study. Post-tests showed that participants who had noticed holes in their vocabulary had indeed learned more words compared to participants who had not. This held both for the experimental group as well as those participants in the control group who later reported to have noticed holes. Thus, when we become aware of vocabulary holes, the first step to improve our vocabulary is already taken.

The current study examined whether the vocabulary skills of sequential bilingual children who learned Cantonese as a home language (L1) and English as a second language (L2) were predicted by the amount of L1 and L2 used at home. Ninety-two preschool children who learned Cantonese as L1 were recruited from a Head Start program. The amounts of L1 and L2 used at home were measured using parent questionnaires. Mixed patterns of L1 and L2 use were found across family members and home activities. After controlling for time spent in preschool, regression analyses showed that the amount of L1 and L2 used by individual family members, with the exception of older siblings, was not significantly linked to children's vocabulary skills. In contrast, the language used during some home activities such as dinner and book reading significantly predicted children's vocabulary knowledge. Implications for family involvement in facilitating children's vocabulary development are discussed.

We investigated the extent to which second-language (L2) learning is influenced by the similarity of grammatical features in one's first language (L1). We used event-related potentials to identify neural signatures of a novel grammatical rule – grammatical gender – in L1 English speakers. Of interest was whether individual differences in L2 proficiency and age of acquisition (AoA) influenced these effects. L2 and native speakers of French read French sentences that were grammatically correct, or contained either a grammatical gender or word order violation. Proficiency and AoA predicted Left Anterior Negativity amplitude, with structure violations driving the proficiency effect and gender violations driving the AoA effect. Proficiency, group, and AoA predicted P600 amplitude for gender violations but not structure violations. Different effects of grammatical gender and structure violations indicate that L2 speakers engage novel grammatical processes differently from L1 speakers and that this varies appreciably based on both AoA and proficiency.

A major benefit of computational models is their ability to demonstrate which theoretical assumptions are truly necessary to explain a pattern of data. Dijkstra, Wahl, Buytenhuijs, van Halem, Al-jibouri, de Korte, and Rekké (in press) have impressively shown with Multilink that it is possible to account for a range of findings from bilingual lexical decision, word naming, and forward and backward translation tasks with an integrated lexicon, without lateral connections between translation equivalents, and without inhibition. In this commentary, we consider the applicability of the current model to other multilingual language production tasks, and note where the model's assumptions might need revision as its scope is expanded.

The present study examines the influence of language proficiency and language combination on bilingual lexical access using category fluency in 109 healthy speakers. Participants completed a category fluency task in each of their languages in three main categories (animals, clothing, and food), each with two subcategories, as well as a language use questionnaire assessing their proficiency. Five language combinations were examined (Hindi–English, Kannada–English, Mandarin–English, Spanish–English, and Turkish–English). Multivariate analyses of variance revealed that the average number of correct items named in the category fluency task across the three main categories varied across the different groups only in English and not the other language. Further, results showed that language exposure composite (extracted from the questionnaire using a principal component analysis) significantly affected the average number of items named across the three main categories. Overall, these results demonstrate the effects of particular language combinations on bilingual lexical access and provide important insights into the role of proficiency on access.

Self-ratings of language proficiency are ubiquitous in research on bilingualism, but little is known about their validity, especially when the same scale is used across different types of bilinguals. Self-ratings and picture naming data from 1044 Spanish–English and 519 Chinese–English bilinguals were analyzed in five between- and within-population comparisons. Chinese–English bilinguals scored more extremely than Spanish–English bilinguals, and in opposite directions at different endpoints of the self-ratings scale. Regrouping bilinguals by dominant language, instead of language membership, reduced discrepancies but significant group differences remained. Population differences appeared even in English, though this language is shared between populations. These results demonstrate significant problems with self-ratings, especially when comparing bilinguals of different language combinations; and subgroups of bilinguals who speak the same languages but vary in acquisition history and/or dominance. Objective proficiency measures (e.g., picture naming or proficiency interviews) are superior to self-ratings, to maximize classification accuracy and consistency across studies.

A question central to bilingualism research is whether representations from the contextually inappropriate language compete for lexical selection during language production. It has been argued recently that the extent of interference from the non-target language may be contingent on a host of factors. In two studies, we investigated whether factors such as word-type and individual differences in inhibitory control capacities influence lexical selection via a cross-modal picture-word interference task and a non-linguistic Simon task. Highly proficient French–English bilinguals named non-cognate and cognate target pictures in L2 (English) while ignoring auditory distractors in L1 (French) and L2. Taken together, our results demonstrated that lexical representations from L1 are active and compete for selection when naming in L2, even in highly proficient bilinguals. However, the extent of cross-language activation was modulated by both word-type and individual differences in inhibitory control capacities.

The finding that noun production is slower and less accurate in bilinguals compared to monolinguals is well replicated, but not well understood. This study examined the two prominent theoretical accounts for this bilingual effect: weaker links and cross-language interference. Highly proficient Mandarin–English bilinguals and English-speaking monolinguals named pictures in which the effects of grammatical class, word frequency and translatability were examined. While bilinguals were slower overall than monolinguals in both L1 and L2, the magnitude of this bilingual effect was smaller for verbs than for nouns. Bilinguals showed a larger production advantage for high vs. low frequency words in their L2 relative to monolinguals and their L1. Bilinguals also showed an advantage for words with greater translatability, which did not differ across grammatical categories. The findings lend partial support to the weaker links account, and reveal cross-language facilitation rather than interference.

Recent evidence demonstrates that lexical-semantic connections emerge over the second year of life for monolingual children. Yet, little is known about the developing lexical-semantic organization of children acquiring two languages simultaneously. Two- to 4 year-old French–Spanish bilingual children completed a within-language auditory semantic priming task in both of their languages, while event-related potentials (ERPs) were recorded. The results revealed that bilingual children exhibited sensitivity to taxonomic relationships between words in each of their languages, but the pattern of brain activity varied across the dominant (DL) and the non-dominant (NDL) languages. While the N2 occurred for both languages, the N400 appeared for target words in the DL only and the late anterior negativity for target words in the NDL only. These findings indicate that words are organized taxonomically in the bilinguals’ lexicons. However, the patterns of brain activity suggest that common and distinct neural resources underlie lexical-semantic processing in each language.

In their keynote paper, Dijkstra, Wahl, Buytenhuijs, van Halem, Al-jibouri, de Korte, and Rekké (2018) present a computational model of bilingual word recognition and translation, Multilink, that integrates and further refines the architecture and processing principles of two influential models of bilingual word processing: the Bilingual Activation Model (BIA/BIA+) and the Revised Hierarchical model (RHM). Unlike the earlier models, Multilink has been implemented as a computational model so its design principles and assumptions can be compared with human processing data in simulation studies – which is an important step forward in model development and refinement. But Multilink also leaves behind an important theoretical advancement that was touched upon in extending BIA to BIA+ (Dijkstra & Van Heuven, 2002): how linguistic context influences word processing. In their presentation of BIA+, Dijkstra and Van Heuven (2002) hypothesized that syntactic and semantic aspects of sentence context may affect the word identification system. Theoretically, this was an important step forward, as none of the bilingual word processing models (and few monolingual word processing models, for that matter) had incorporated linguistic context, and at that time only a handful of empirical studies had examined how linguistic context affects bilingual word processing. However, in the past 15 years a significant body of empirical work has been published that examines how semantic and syntactic information in sentences impacts word processing in bilinguals. These important insights are not incorporated in the Multilink model.

This study assessed whether bilingual memory is susceptible to the extreme processing demands of professional simultaneous interpreters (PSIs). Seventeen PSIs and 17 non-interpreter bilinguals completed word production, lexical retrieval, and verbal fluency tasks. PSIs exhibited enhanced fluency in their two languages, and they were faster to translate words in both directions. However, no significant differences emerged in picture naming or word reading. This suggests that lexical enhancements in PSIs are confined to their specifically trained abilities (vocabulary search, interlingual reformulation), with no concomitant changes in other word-processing mechanisms. Importantly, these differences seem to reflect specifically linguistic effects, as both samples were matched for relevant executive skills. Moreover, only word translation performance correlated with the PSIs’ years of interpreting experience. Therefore, despite their tight cooperation, different subcomponents within bilingual memory seem characterized by independent, usage-driven flexibility.

Does reading Pinyin, a Roman alphabet transcription of Chinese, cause the implicit activation of the corresponding Chinese character? To address this question, we carried out two experiments with adult Chinese learners, measuring interference in character reading in a modified Stroop task. Participants first made a meaning judgment on a Pinyin word, and then judged the printed color of a character that was either visually related or unrelated to the character that corresponded to the Pinyin word. A character orthographic interference effect was observed for advanced Chinese learners but not intermediate Chinese learners. The proficiency-dependent emergence of this interference effect suggests its dependence on Chinese character reading experience. For models of Chinese reading, the results demonstrate the role of the character as a gateway to meaning that, through reading experience, comes to be routinely involved in reading for meaning, whether the input is a character or an alphabetic spelling.

Although international students experience lower attainment at university than home students (Morrison et al., 2005), reasons are poorly understood. Some question the role of language proficiency as international students come with required language qualifications. This study investigated language and literacy of international students who successfully met language entry requirements and those of home students, matched on non-verbal cognition, studying in their native language. In a sample of 63 Chinese and 64 British students at a UK university, large and significant group differences were found at entry and eight months later. Furthermore, language and literacy indicators explained 51% of variance in the Chinese group's grades, without predicting the home students’ achievement. Thus language proficiency appears predictive of academic outcomes only before a certain threshold is reached, and this threshold does not correspond to the minimum language entry requirements. This highlights a systematic disadvantage with which many international students pursue their education.

How flexible is bilingual language control and how does it adapt to the linguistic context of a conversation? We address this by looking at the pattern of switch costs in contexts involving mostly the use of a dominant or non-dominant language. This linguistic context affected switching patterns: switching was equally costly for both languages in a dominant (L1) context, while switching was harder for the weaker language in the non-dominant (L2) context. Also, naming latencies for each language were affected by the linguistic contexts: only the dominant L1 context led to slower latencies for the dominant language. This latter finding was also present when looking at the LPC component, which may reveal differences in the way inhibitory control is applied depending on the linguistic context. These results reveal that the bilingual language control system is flexible and that it adapts to the linguistic context in which the speaker is placed.

In their keynote article, Dijkstra, Wahl, Buytenhuijs, van Halem, Al-jibouri, De Korte & Rekke (2018) propose a new model that aims to integrate and take care of the possible shortcomings of both the Revised Hierarchical Model (RHM, Kroll & Stewart, 1994) and Bilingual Interactive Activation model (BIA and several of its later versions, Dijkstra & Van Heuven, 1998). They begin their proposal by examining the objections/issues raised by Brysbaert and Duyck (2010) on RHM. It is well known that RHM is a developmental, production-based model which mostly predicted performance on translation-based tasks albeit with different predictions for translation recognition vs. production with regard to second language proficiency; BIA being a connectionist model of bilingual word recognition majorly emphasized on language non –selective selection and parallel language activation. Having been developed in and around Dutch (English as the second language), it took cognate status and orthographic similarity between words very seriously. Cognate status and orthographic similarity as factors won't count much as theoretical constructs around which a hypothesis could be developed if we look round the diverse types of orthographies and phonologies we find around the world.

In two experiments with Telugu–English bilinguals, we examined if bilingual speakers are sensitive towards an interlocutor's (cartoon) relative language proficiency when they voluntarily selected a language for object naming. After familiarization with four different cartoons with varied L2 proficiency, participants did a voluntary naming task. In Experiment 1, participants explicitly indicated their choice of language before naming objects. In Experiment 2, participants named the objects directly. In both experiments, language choices and switchrates were thoroughly modulated by the participants’ perceived linguistic ability of the cartoon. However, awareness of perceived proficiency of the cartoons did not modulate naming latency. These results provide strong support for the adaptive control hypothesis, showing that bilingual speakers are sensitive to their interlocutor's language needs and this influences how they plan their language use. The results provide evidence of speakers taking into consideration the language proficiency of interlocutors, suggesting extreme adaptability of the bilingual mind.