Language control in the bilingual brain has remained in the limelight of research over the past decades. However, the mechanisms underlying bilingual language control may be more intricate than typically assumed due to the hierarchical nature of language. This study aimed to investigate the dynamics of bilingual language control at the phonetic level. Participants, who were speakers of Chinese, English and German, named the letters of the alphabet in English (L2) or German (L3) following an alternating language-switching paradigm. Two sets of letters were selected, differing in the phonological similarity of their pronunciation across the two languages, thereby allowing the exploration of cross-language phonological influences. Each participant completed two sessions of letter-naming tasks. In one session, seven phonologically similar letters were randomly repeated either in single-language blocks or in alternate-language blocks. In the other session, seven phonologically dissimilar letters were similarly manipulated. The results indicated local inhibition, reflected by switch costs and global inhibition, reflected by mixing costs. Reversed language dominance, another indicator of global inhibition, was not observed. However, there was a tendency for larger global inhibition to be applied to the more dominant language. Moreover, there was significantly faster naming for phonologically similar letters compared to dissimilar ones, suggesting a facilitation effect for both English and German, irrespective of whether letter naming occurred in single- or alternate-language blocks. These findings provided evidence for the role of inhibitory and facilitative mechanisms at the phonetic level, suggesting language-specific control in the bilingual brain and underscoring the complexity and dynamics of managing language control across multiple levels of processing.

Effects of language switching in bilinguals have been extensively investigated, but the majority of studies have focused on switching in language production. Here we explored intrasentential switching between Chinese and English, employing a self-paced reading paradigm, with Chinese/English using radically different orthographic systems. In addition, we investigated whether L2 (English) proficiency influences switch costs. Results revealed that switch costs emerged only when switching into L1 (Chinese); by contrast, when switching into L2, a less reliable facilitatory effect was observed. L2 proficiency affected reading speed for English stimuli, but it did not directly modulate switch costs. Moreover, we have integrated various findings from previous research and identified that the use of different comparison patterns is a major contributing factor to the inconsistency in results among prior studies. We suggest that in cross-script language switching, switch costs stem from a general cognitive control mechanism rather than from activation within the bilingual mental lexicon.

Multilingual language control is commonly investigated using picture-naming paradigms with explicit instructions when to switch between languages. In daily life, language switching also occurs without external cues. Cued language-switching tasks usually show a switch cost (i.e., slower responses on switch than non-switch trials). Findings of switch costs in response times are mixed for voluntary language switching. This pre-registered study uses a bilingual picture-naming paradigm to compare voluntary and cued language switching in 25 highly proficient Dutch-English bilinguals using EEG. We analysed the N2 ERP component and midfrontal theta oscillations, two common electrophysiological markers of cognitive control in task and language switching. We observed significantly smaller behavioural switch costs in the voluntary task. This suggests that voluntary language switching is less effortful than switching based on external cues. However, we found no electrophysiological switch effects in either task. We discuss factors which may contribute to the inconsistency between behavioural and electrophysiological findings.

Bilinguals frequently switch between languages. The present study examined cued language switching (CLS) longitudinally in bilingual Turkish–Dutch children with (n = 11) and without (n = 30) developmental language disorder (DLD) in a three-wave design with one-year intervals. We studied effects of dominance, indexed by language proficiency and exposure, on overall switching performance and the costs associated with switching between languages. Results show limited evidence for overall costs associated with language switching (i.e., only mixing costs in reaction times [RTs]). Further, accuracy on CLS increased with increasing dominance in the trial language. Moreover, better performance, and larger switching costs, were found in the majority (Dutch) compared to the minority (Turkish) language. These results are discussed in light of the sociolinguistic context. As hypothesized, more errors, longer RTs and slightly larger mixing costs were observed in children with DLD, suggesting overall word retrieval difficulties and difficulties with cognitive control.

In processing their two languages, bilinguals have to selectively attend to the target language and reduce interference from the non-target language. This experience may have specific cognitive consequences on Executive Functions (EF) through bilingual language processing. Some studies found cognitive consequences in executive functioning skills. However, other studies did not replicate these findings or found a bilingual disadvantage. The aim of this study was to test for the cognitive consequences of bilingualism in EF among a large number of young adults using a latent variable approach, to rule out non-EF task differences as an explanation for inconsistency across studies. Also, we were interested in testing the EF structure using the Confirmatory Factor Analysis (CFA) approach. The results did not support a cognitive consequence of bilingualism and also the EF structure was the same for both groups. We discuss other possible variables that might contribute to the mixed results across studies.

Bilinguals may choose to speak a language either at their own will or in response to an external demand, but the underlying neural mechanisms in the two contexts is poorly understood. In the present study, Chinese–English bilinguals named pairs of pictures in three conditions: during forced-switch, the naming language altered between pictures 1 and 2. During non-switch, the naming language used was the same. During free-naming, either the same or different languages were used at participants' own will. While behavioural switching costs were observed during free-naming and forced-switching, neuroimaging results showed that forced language selection (i.e., forced-switch and non-switch) is associated with left-lateralized frontal activations, which have been implicated in inhibitory control. Free language selection (i.e., free-naming), however, was associated with fronto-parietal activations, which have been implicated in self-initiated behaviours. These findings offer new insights into the neural differentiation of language control in forced and free language selection contexts.

The goal of the current paper is to investigate effects of multilingualism regarding emotional competence (EC). We argue that there might be two paths of influence that connect multilingualism and EC. First, we assume that multilingualism represents a linguistically and culturally heterogeneous context that may stimulate the development of EC. Second, cognitions, such as executive control or divergent thinking, might be an important condition for or constituent of emotions. Since cognitive abilities are sometimes assumed to be positively influenced by multilingualism (called the cognitive resp. bilingual advantage hypothesis), multilingualism might affect EC by boosting these cognitive functions. In an initial pre-study (N = 85) we found that two EC subcomponents were significantly predicted by degree of multilingualism (DM). In a second study (N = 989), we found that DM significantly predicted EC directly and was mediated by cultural heterogeneity but not by language switching, executive functions, or divergent thinking.

While research on bilingual language processing is sensitive to different usage contexts, monolinguals are still often treated as a homogeneous control group, despite frequently using multiple varieties that may require engagement of control mechanisms during lexical access. Adapting a language-switching task for speakers of (Scottish) Standard English and Orcadian Scots, we demonstrate switch cost asymmetries with longer naming latencies when switching back into Orcadian. This pattern, which is reminiscent of unbalanced bilinguals, suggests that Orcadian is the dominant variety of these participants – despite the fact they might be regarded as English monolinguals because of sociolinguistic factors. In conjunction with the observed mixing cost and cognate facilitation effect (indicative of proactive language control and parallel language activation, respectively), these findings show that ‘monolinguals’ need to be scrutinised for routine use of different varieties to gain a better understanding of whether and how mechanisms underlying their lexical access resemble those of bilinguals.

The multidimensionality of the bilingual experience makes the investigation of bilingualism fascinating but also challenging. Although the literature distinguishes several aspects of bilingualism, the measurement methods and the relationships between these aspects have not been clearly established. In a group of 171 relatively young Polish–English bilinguals living in their first-language environment, this study investigates the relationships between the multiple measures of bilingualism. The study shows that language entropy – an increasingly popular measure of the diversity of language use – reflects a separate aspect of the bilingual experience from language-switching and language-mixing measures. The findings also indicate that language proficiency is not a uniform aspect of the bilingual experience but a complex construct that requires appropriately comprehensive measurements. Collectively, the findings contribute to the discussion on the best practices for quantifying bilingualism.

This study investigated how natural language use influences inhibition in language-unbalanced bilinguals. We experimentally induced natural patterns of language use (as proposed by the Adaptive Control Hypothesis) and assessed their cognitive after-effects in a group of 32 Polish–English bilinguals. Each participant took part in a series of three language games involving real conversation. Each game was followed by two inhibition tasks (stop-signal task and Stroop task). The manipulation of language use in the form of language games did not affect the behavioural measures, but it did affect ERPs. Performance of the inhibition tasks was accompanied by a reduction of P3 and the N450 amplitude differences after games involving the use of L2. The ERP modulations suggest that for bilinguals living in an L1 context the use of L2 enhances neural mechanisms related to inhibition. The study provides the first evidence for a direct influence of natural language use on inhibition.

Language control is important for bilinguals to produce words in the right language. While most previous studies investigated language control using visual stimuli with vocal responses, language control regarding auditory stimuli and manual responses was rarely examined. In the present study, an alternating language switching paradigm was used to investigate language control mechanism under two input modalities (visual and auditory) and two output modalities (manual and vocal) by measuring switch costs in both error percentage and reaction time (RT) in forty-eight Cantonese–English early bilinguals. Results showed that higher switch costs in RT were found with auditory stimuli than visual stimuli, possibly due to shorter preparation time with auditory stimuli. In addition, switch costs in RT and error percentage could be obtained not only in speaking, but also in handwriting. Therefore, language control mechanisms, such as inhibition of the non-target language, may be shared between speaking and handwriting.

The assumption that everyday language switching trains bilinguals’ executive functions (EF) presupposes that language switching engages domain-general EF. This study examined associations between three types of tasks in a group of Finnish-English late bilinguals: everyday language switching frequency assessed with Ecological Momentary Assessment, language switching performance on a cued bilingual naming task, and EF as measured with Simon, Flanker, and Number-letter tasks. Cued switching performance showed mainly positive associations with EF performance, but the associations between everyday language switching and cued switching performance, and between everyday switching and the EF tasks were largely against our hypotheses. The findings indicate that participants with lower monitoring capacity make more everyday language switches. This speaks against the idea that everyday language switching would facilitate executive functioning. The results suggest that associations between language switching and general EF are more complex than current models assume.

Many language pairs chosen in language switching studies differ randomly on multiple linguistic levels, thus obscuring the nature of switching costs. Contact-induced languages, i.e., creoles (e.g., Spanish-based Palenquero) and mixed languages (e.g., Media Lengua), having arisen in intense language contact scenarios, relate systematically to their source languages by displaying high proportions of cognates or shared grammar. This configuration can speak to the relative contribution of lexicon and grammar to switching costs. Results from a production and comprehension task show that switching costs are systematically tied to a language pair's grammatical distance. This suggests that switching costs may result from the re-generation of the morphosyntactic frame on switch trials. Emphasizing the value of testing psycholinguistic theories outside of the usual Western populations, the current study provides insight into the degree of shared mental representations between contact-induced languages and their source languages.

To investigate whether similar control processes are used during single and dual language production, we compared register switching (formal and informal speech in the same language) vs. language switching (French and English). The results across two experiments showed a positive correlation of overall register- and language-switch costs and similar formal French switch costs across the two switching tasks. However, whereas increasing the cue-to-stimulus interval resulted in a reduction of language-switch costs, register-switch costs were unaffected by the interval manipulation. This difference in switch-cost pattern indicates that control processes are not entirely identical during single and dual language production.

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.

Language switching experience is assumed to have an effect on domain-general control abilities in bilinguals, but previous studies on the relationship between these two variables have generated mixed results. The present study investigated the effects of bilingual experiences on the interaction between language switching and domain-general control. Thirty-two Dutch–French bilingual young adults executed a bilingual categorisation task to assess their language switching abilities and a Simon task to assess domain-general control. The results show that global response times on the Simon task were correlated to the forward switch cost (from L1 to L2); moreover, interestingly, the forward switch cost was found to be related to recent language exposure but not to the age of second language acquisition. We suggest a monitoring account of language switching to integrate the first finding with previous studies and we interpret the second finding as support for the adaptive control hypothesis.

Previous studies have demonstrated that language switching in bilinguals can be affected by a number of variables, including the processing context. Here, we used a modified language-switching task combined with a Stroop paradigm, which manipulated the context of the task, to examine the impact of processing context on switch costs. The results of both Experiment 1 and Experiment 2 showed that the switch costs and the level of asymmetry in the switch costs are larger in the conflicting context than in the non-conflicting context, suggesting that the processing context affects the switch costs. In addition, the results of Experiment 2 revealed that individual variances in cognitive control capacity also play a role in the overall magnitude of the switch costs. Critically, processing context effects can be modulated by individual variance in cognitive control capacities. The results of this study are discussed within the framework of classic models of bilingual language control (e.g., the inhibitory control model).

Bilinguals sometimes outperform monolinguals on tasks involving cognitive control – the regulation of mental activity when confronted with information-processing conflict – perhaps stemming from experience monitoring for and resolving conflict between languages. We test the hypothesis that bilingualism affects moment-to-moment cognitive-control recruitment by examining how trial history influences bilinguals’ and monolinguals’ behavioral performance and associated neural activity on a Stroop task. We assessed dynamic effects of preceding trial conflict on current trial performance to separate the ability to proactively detect conflict (performance on new instances of conflict) from the ability to reactively recruit cognitive control (performance on trials following conflict). Across two experiments, monolinguals’ – but not bilinguals’ – accuracy decreased after non-conflict trials, i.e., when detecting initial conflicts. Bilinguals exhibited greater conflict-detection activity in ventrolateral prefrontal cortex (vlPFC/insula; BA 47) within a language-switching network, suggesting that they may monitor for information-conflict more proactively than monolinguals by recruiting brain regions involved in switching languages.

Bilinguals often switch languages as a function of the language background of their addressee. The control mechanisms supporting bilinguals' ability to select the contextually appropriate language are heavily debated. Here we present four experiments in which unbalanced bilinguals named pictures in their first language Dutch and their second language English in mixed and blocked contexts. Immersive virtual reality technology was used to increase the ecological validity of the cued language-switching paradigm. Behaviorally, we consistently observed symmetrical switch costs, reversed language dominance, and asymmetrical mixing costs. These findings indicate that unbalanced bilinguals apply sustained inhibition to their dominant L1 in mixed language settings. Consequent enhanced processing costs for the L1 in a mixed versus a blocked context were reflected by a sustained positive component in event-related potentials. Methodologically, the use of virtual reality opens up a wide range of possibilities to study language and communication in bilingual and other communicative settings.

We assessed language switch and mixing costs in a language-general semantic categorization task and examined how these costs relate to general inhibition and set shifting capacities. The participants were 51 native Finnish subjects with English as L2. The results showed significant symmetric language switch costs and, unexpectedly, a mixing advantage in L2: reaction times were faster in the mixed language block than in the single language block. The interactions with the general executive functions showed no consistent overall pattern. We argue that the L2 mixing advantage stems from statistical facilitation in line with a horse race model, or from opportunistic planning as suggested by the Adaptive Control hypothesis. We argue that the results overall indicate that lexical access in language reception is non-selective.