Bilingual Language Production Research Articles

Language dominance influences bilingual lexical selection quantitatively but not qualitatively in language production: Evidence from Chinese-English bilinguals

Previous research on bilingual lexical selection has mainly investigated the influence of the dominant first language (L1) on the speech production of the non-dominant second language (L2). However, research in the reverse direction is quite rare. Here we examined the influence in both directions using a bilingual picture-word interference (PWI) paradigm, where Chinese-English bilinguals named pictures in one language while ignoring distractors presented in another language. In both L1 and L2 naming, naming times were longer when distractors were semantically related to the picture names than when they were unrelated, resulting in a between-language semantic interference effect. In contrast, naming times were shorter when distractors were translations of the picture names than when they were unrelated, resulting in a translation facilitation effect. The results suggested that the mechanism of lexical selection in language production was in line with the within-language competition theory, showing no qualitative differences in the mechanism between L1 and L2. At the same time, the semantic interference effect sizes were not significantly different in L1 and L2 production, but the translation facilitation effect size was significantly larger in L2 production than in L1 production, indicating there exist quantitative differences in the mechanism of lexical selection between L1 and L2. A computational model was constructed to simulate naming performance and confirmed the accuracy of the within-language competition view in L1 and L2 lexical selection for Chinese-English bilinguals. We concluded that language dominance influences bilingual lexical selection quantitatively but not qualitatively in bilingual language production.

The effects of habitual code-switching in bilingual language production on cognitive control

AbstractThis study explored how bilingual code-switching habits affect cognitive shifting and inhibition. Habitual code-switching from 31 Mandarin–English bilingual adults were collected through the Language and Social Background Questionnaire (Anderson, Mak, Keyvani Chahi & Bialystok, 2018) and the Bilingual Switching Questionnaire (Rodriguez-Fornells, Krämer, Lorenzo-Seva, Festman & Münte, 2012). All participants performed verbal and nonverbal switching tasks, including the verbal fluency task, a bilingual picture-naming and colour-shape switching task. A Go/No-go task was administered to measure the inhibitory control of participants.Frequent bilingual switchers showed higher efficiency in both English to Chinese verbal switching and nonverbal cognitive shifting. Additionally, bilinguals with intensive dense code-switching experience outperformed in the Go/No-go task. In general, the study revealed the connections between bilinguals’ intensity of single-language context experience and goal maintenance efficiency, which partially supported the Adaptive Control Hypothesis’ prediction (Green & Abutalebi, 2013). Besides, it also indicated the facilitations of bilinguals’ dense code-switching experience on their conflicts monitoring and response inhibition.

Nonverbal cognitive control training increases the efficiency of frontal-subcortical collaboration for bilingual language control

Domain-general cognitive control is closely related to language control during bilingual language production. Previous neural imaging studies have revealed a highly overlapped but rewired brain network for language control and nonverbal cognitive control. In the present study, we examined this issue from a training perspective. Two groups of participants performed the language switching task at pre-and post-tests during functional magnetic resonance imaging (fMRI) scanning. After the pre-test, the experimental group received 8-day training in a non-verbal switching task, while the control group performed an unrelated color judgement task. We found that only the experimental group but not the control group showed decreased strength of connectivity from the ventral lateral frontal cortex to the left caudate nucleus and from the medial surface of the frontal lobe to the left thalamus. These results indicate an increased efficiency after nonverbal training for the frontal cortex to implement domain-general suppression and monitoring in a domain-specific conflict context during bilingual language and lexical selections. This study is the first to investigate the transfer effects of nonverbal cognitive control on the brain network of bilingual language control and shed light on the mechanisms of how domain-general cognitive control may underpin bilingual language control.

The cerebellum and cognition: further evidence for its role in language control.

The cognitive function of the human cerebellum could be characterized as enigmatic. However, researchers have attempted to detail the comprehensive role of the cerebellum in several cognitive processes in recent years. Here, using functional magnetic resonance imaging (fMRI) and transcranial direct current stimulation (tDCS), we revealed different functions of bilateral cerebellar lobules in bilingual language production. Specifically, brain activation showed the bilateral posterolateral cerebellum was associated with bilingual language control, and an effective connectivity analysis built brain networks for the interaction between the cerebellum and the cerebral cortex. Furthermore, anodal tDCS over the right cerebellum significantly optimizes language control performance in bilinguals. Together, these results reveal a precise asymmetrical functional distribution of the cerebellum in bilingual language production, suggesting that the right cerebellum is more involved in language control. In contrast, its left counterpart undertakes a computational role in cognitive control function by connecting with more prefrontal, parietal, subcortical brain areas.

“Antagonistic” cooperation of control regions in bilingual language production: An effective connectivity study

The dorso-lateral prefrontal cortex (DLPFC) and the anterior cingulate cortex (ACC) are two main regions that support bilingual language control during language production. Previous studies have suggested that the regions work together in language control processes. However, how they cooperate with each other during bilingual language production is far from clear. We addressed this issue by recruiting bimodal bilingual participants whose two languages could be separated at a neural level. Functional magnetic resonance imaging scans were acquired from the participants as they performed a dual-language production task and a spoken-production task. Dynamic causal modelling (DCM) was used to analyse the effective connectivity between the ACC and the DLPFC as well as the causal relationships among the control regions and language regions. We found that the ACC had positive effective connectivity to the DLPFC, left precentral gyrus and left superior temporal gyrus, while the DLPFC had negative effective connectivity to the other three regions. A similar pattern of effective connectivity between the control regions and language regions was also found in the spoken-production task. These results showed that the ACC may promote the production of the target language, while the DLPFC has an inhibitory effect in language production. The findings suggest an antagonistic relationship between the DLPFC and ACC that cooperatively ensures fluent language production in bilinguals.

Prospective memory in bilinguals and monolinguals: ERP and behavioural correlates of prospective processing in bilinguals

Prospective memory (PM) allows us to form intentions and execute them in the future. Successful retrieval of prospective intentions depends on adequate context monitoring and disengagement from the ongoing task. These processes are also central in predicting incoming language information and guiding language production in bilinguals. We investigated if different bilingual experiences (early/late bilinguals, monolinguals) modulate performance in PM tasks that varied in attentional requirements (focal vs. non-focal). Behavioural and event-related potential (ERP) results indicated that early bilinguals differed from late bilinguals and monolinguals in how they performed the prospective task. Specifically, they showed larger differences between the ongoing activity and the prospective task in the N300 and P3b components when performing the more difficult non-focal PM task, indicating that they engaged in monitoring/updating to adapt to the task’s demands. These differences were not observed in late bilinguals and monolinguals, suggesting that prospective processing is dependent on the bilingual experience.

Ecological validity and bilingual language control: voluntary language switching between sentences

ABSTRACT Few language switching studies have found conditions in which there is no significant cost to switching languages. Since language-switch costs are a measure of language control, this could be seen as evidence for the ubiquity of this process in bilingual language production. However, one claim is that ecologically valid bilingual contexts lead to small or even absent switch costs. To further investigate this, we examined voluntary language switching between sentences. This ecologically more valid setup (compared to the more prominent involuntary language switching setup with single word production) resulted in switch costs for sentences produced in the second language, but no significant switch costs for sentences produced in the first language, whereas involuntary language switching between sentences resulted in substantial switch costs across both languages. These results indicate that more ecologically valid contexts can lead to circumstances that might require little to no language control.

Is there proactive inhibitory control during bilingual and bidialectal language production?

The bilingual language control literature generally assumes that cross-language interference resolution relies on inhibition of the non-target language. A similar approach has been taken in the bidialectal language control literature. However, there is little evidence along these lines for proactive language control, which entails a control process that is implemented as an anticipation of any cross-language interference. To further investigate the possibility of proactive inhibitory control, we examined the effect of language variety preparation time, by manipulating the cue-to-stimulus interval, on parallel language activation, by manipulating cognate status. If proactive language control relies on inhibition, one would expect less parallel language activation (i.e., a smaller cognate facilitation effect) with increased proactive inhibitory control (i.e., a long cue-to-stimulus interval). This was not the case with either bilinguals or bidialectals. So, the current study does not provide evidence for proactive inhibitory control during bilingual and bidialectal language production.

Is it easier to use one language variety at a time, or mix them? An investigation of voluntary language switching with bidialectals.

Previous language production research with bidialectals has provided evidence for similar language control processes as during bilingual language production. In the current study, we aim to further investigate this claim by examining bidialectals with a voluntary language switching paradigm. Research with bilinguals performing the voluntary language switching paradigm has consistently shown two effects. First, the cost of switching languages, relative to staying in the same language, is similar across the two languages. The second effect is more uniquely connected to voluntary language switching, namely a benefit when performing in mixed language blocks relative to single language blocks, which has been connected to proactive language control. If a similar pattern could be observed with bidialectals in a voluntary language switching paradigm, then this would provide additional evidence in favor of similar control processes underlying bidialectal and bilingual language production.

Lexical selection in bilingual language production

Abstract The goal of this study is to examine whether bilingual speakers can inhibit one language while naming pictures in the other. In two picture-word interference task experiments, Spanish-English and English-Spanish bilinguals named pictures in Spanish. We used language-neutral (nonword) interfering stimuli to probe the phonological activation of the nontarget language (English). Three different interfering stimulus conditions were presented: nonwords phonologically related to the Spanish picture name (Phono-Spanish), nonwords phonologically related to the English picture name (Phono-English) and phonologically unrelated nonwords (Unrelated). When participants named pictures in Spanish (Experiment 1), facilitation was found for both groups in the Phono-Spanish condition. No interference was found in the Phono-English condition for either group. From this result and the results of a control experiment in which participants named pictures in English (Experiment 2), we argue that under some circumstances, bilinguals are able to effectively inhibit the nontarget language during language production.

Inhibitory control training reveals a common neurofunctional basis for generic executive functions and language switching in bilinguals

BackgroundThe neural networks underpinning language control and domain-general executive functions overlap in bilinguals, but existing evidence is mainly correlative. Here, we present the first neurofunctional evidence for a transfer effect between (domain-general) inhibitory control and language control through training. We trained Chinese–English bilinguals for 8 days using a Simon task taxing the inhibitory control system, whilst an active control group was trained with a color judgment task that does not tax the inhibitory control system. All participants performed a language-switching task before and after training. It has been suggested that the activity of the left DLPFC was associated with domain-general top-down cognitive control (Macdonald et al. Science 288: 1835–1838, 2000) and bilingual language control (Wang et al. Neuroimage 35: 862–870, 2007). In addition, the dACC was closely related to the conflict detection (Abutalebi et al. Cereb Cortex 18:1496–1505, 2008). Last, the activity of the left caudate has been linked with lexical selection (Abutalebi et al. Cereb Cortex 18:1496–1505, 2008), especially the selection of the weak language (Abutalebi et al. Cortex 49: 905–911, 2013). Therefore, we focused on these three regions of interest (ROIs) where neural changes associated with transfer were expected to occur.ResultsThe results showed a negative correlation between changes in activation levels in the left dorsolateral prefrontal cortex (DLPFC) and changes in the switch cost magnitude in the language-switching task in the training group but not in the control group, suggesting that the DLPFC plays a critical role in the transfer effect from domain-general executive functions to language control. However, there was no measurable effect in the anterior cingulate cortex or left caudate nucleus, suggesting that the inhibitory control training increased the neural efficiency for language production in bilinguals in terms of attention shifting and conflict resolution, but the training did not affect conflict detection and lexical selection.ConclusionThese findings showed how cognitive training evidence can help establish a causational link between the neural basis of domain-general executive functions and language control in bilinguals.

Morphological generalization in bilingual language production: Age of acquisition determines variability

ABSTRACT Morphological variability in bilingual language production is widely attested. Producing inflected words has been found to be less reliable and consistent in bilinguals than in first-language (functionally monolingual) L1 speakers, even for bilingual speakers at advanced proficiency levels. The sources for these differences are not well understood. The current study presents a detailed investigation of morphological generalization processes in bilingual speakers’ language production. We examined past participle formation of German using an elicited-production experiment containing nonce verbs with varying degrees of similarity to existing verbs testing a large group of bilingual Turkish/German speakers relative to L1 German speakers. We compared similarity-based lexical extensions with generalizations of morphological rules. The results show that rule-based generalizations are used less often and more variably within the bilingual group than within the L1 group. Our results also show a selective effect of age of acquisition on the bilingual speakers’ morphological generalizations.

Similar activation patterns in the bilateral dorsal inferior frontal gyrus for monolingual and bilingual contexts in second language production

Language production is a vital process of communication. Although many studies have devoted to the neural mechanisms of language production in bilinguals, they mainly focused on the mechanisms of cognitive control during language switching. Therefore, it is not clear how naming context influences the neural representations of linguistic information during language production in bilinguals. To address that question, the present study adopted representational similarity analysis (RSA) to investigate the neural pattern similarity (PS) between the monolingual and bilingual contexts separately for native and second languages. Consistent with previous findings, bilinguals behaviorally performed worse, and showed greater activation in brain regions for cognitive control including the anterior cingulate cortex and dorsolateral prefrontal cortex in the bilingual context relative to the monolingual context. More importantly, RSA revealed that bilinguals exhibited similar neural activation patterns in the bilateral dorsal inferior frontal gyrus between the monolingual and bilingual contexts in the production of the second language. Moreover, higher cross-context PS in the right inferior frontal gyrus was associated with smaller differences in naming speed of second language between the monolingual and bilingual contexts. These results suggest that similar linguistic representations are encoded for the monolingual and bilingual contexts in the production of non-dominant language.

A common selection mechanism at each linguistic level in bilingual and monolingual language production

The primary goal of research on the functional and neural architecture of bilingualism is to elucidate how bilingual individuals' language architecture is organized such that they can both speak in a single language without accidental insertions of the other, but also flexibly switch between their two languages if the context allows/demands them to. Here we review the principles under which any proposed architecture could operate, and present a framework where the selection mechanism for individual elements strictly operates on the basis of the highest level of activation and does not require suppressing representations in the non-target language. We specify the conjunction of parameters and factors that jointly determine these levels of activation and develop a theory of bilingual language organization that extends beyond the lexical level to other levels of representation (i.e., semantics, morphology, syntax and phonology). The proposed architecture assumes a common selection principle at each linguistic level to account for attested features of bilingual speech in, but crucially also out, of experimental settings.

Patterns and networks of language control in bilingual language production

Many studies have examined the cognitive and neural mechanisms of bilingual language control, but few of them have captured the pattern information of brain activation. However, language control is a functional combination of both cognitive control and language production which demonstrates distinct patterns of neural representations under different language contexts. The first aim of the present study was to explore the brain activation patterns of language control using multivoxel pattern analysis (MVPA). During the experiment, Chinese-English bilinguals were instructed to name pictures in either Chinese or English according to a visually presented cue while being scanned with functional magnetic resonance imaging (fMRI). We found that patterns of neural activity in frontal brain regions including the left dorsolateral prefrontal cortex, left inferior frontal gyrus, left supplementary motor area, anterior cingulate cortex, bilateral precentral gyri, and the left cerebellum reliably discriminated between switch and non-switch conditions. We then modeled causal interactions between these regions by applying effective connectivity analyses based on an extended unified structure equation model (euSEM). The results showed that frontal and fronto-cerebellar connectivity were key components of the language control network. These findings further reveal the engagement of the cognitive control network in bilingual language production.

Second language learning tunes the language control network: a longitudinal fMRI study

ABSTRACT The current longitudinal study investigated how classroom second language (L2) learning modulates the neural correlates of bilingual language control during language production. Chinese college freshmen majoring in English undertook two test sessions (i.e. pre-learning and post-learning) over the course of one year. Specifically, while in the scanner, participants were instructed to name pictures in either their first or second language in response to cues. Behavioral results showed that language switch costs in the post-learning session were reduced as compared to the pre-learning session. fMRI results showed that, compared to the pre-learning session, the connectivity strength between the dorsal anterior cingulate gyrus and the left caudate was increased in the post-learning session. Critically, this increased connectivity strength was correlated with the reduction in language switch costs. These findings suggest that the language control network used during bilingual language production could be modulated by long-term L2 learning in a naturalistic classroom setting.

Lexical selection in bimodal bilinguals: ERP evidence from picture-word interference

ABSTRACT The picture word interference (PWI) paradigm and ERPs were used to investigate whether lexical selection in deaf and hearing ASL-English bilinguals occurs via lexical competition or whether the response exclusion hypothesis (REH) for PWI effects is supported. The REH predicts that semantic interference should not occur for bimodal bilinguals because sign and word responses do not compete within an output buffer. Bimodal bilinguals named pictures in ASL, preceded by either a translation equivalent, semantically-related, or unrelated English written word. In both the translation and semantically-related conditions bimodal bilinguals showed facilitation effects: reduced RTs and N400 amplitudes for related compared to unrelated prime conditions. We also observed an unexpected focal left anterior positivity that was stronger in the translation condition, which we speculate may be due to articulatory priming. Overall, the results support the REH and models of bilingual language production that assume lexical selection occurs without competition between languages.

Language context tunes brain network for language control in bilingual language production

When bilinguals intend to speak in their first (L1) or second language (L2) according to the environment, a brain network involving cortical-subcortical regions is recruited to resolve cross-language interference. Research has found that the activation of these brain regions varies with language contexts. However, previous studies have not yet examined adaptive changes in the interactions of brain regions for different language contexts. To address this gap, we adopted extended unified structural equation modeling (euSEM) to identify the connectivity patterns of the bilingual control network. Twenty-one unbalanced Chinese-English bilinguals were instructed to name pictures in L1-single, L2-single, and dual-language contexts while undergoing functional magnetic resonance imaging (fMRI). We found that unbalanced bilinguals relied on a more functional integrated brain network, which was reflected by clearer core-periphery structures and increased global efficiency, in dual-language and L2-single contexts compared to L1-single context. Furthermore, the pattern of brain connectivity in the dual-language context was more similar to that in the L1-single context than the L2-single context. More importantly, we found more similarities between the connectivity patterns of dual-language and L1-single contexts in bilinguals with lower inhibitory control abilities. These findings provide the first connectivity evidence for the effect of language context on the bilingual language control network, which inhibits the base language and underpins bilinguals’ change along the monolingual-bilingual mode continuum.

Mixed language training enhances proactive language control in bilingual language production

ABSTRACT The present study investigates the effect of mixed language training on the language control mechanism of bilingual language production. Two groups of unbalanced bilinguals were enrolled in pre- and post-tests using the picture naming task, but only the experimental group participated in an eight-day dual-language training session. Event-related potentials (ERPs) showed that, in the experimental group, the N2 mean magnitude was comparable between two languages in the pre-test, but it was larger in the native language (L1) than the second language (L2) in the post-test. In addition, the delta band power was similar between L1 and L2 in the pre-test, but L2 was associated with stronger power than L1 after training. In contrast, the control group showed no significant changes. These findings suggest that increased experience of language use in the dual-language context induces stronger proactive inhibitory control on L1, resulting in its lower activation.

Interactive Alignment and Lexical Triggering of Code-Switching in Bilingual Dialogue.

When bilingual speakers use two languages in the same utterance, this is called code-switching. Previous research indicates that bilinguals’ likelihood to code-switch is enhanced when the utterance to be produced (1) contains a word with a similar form across languages (lexical triggering) and (2) is preceded by a code-switched utterance, for example from a dialogue partner (interactive alignment/priming of code-switching). Both factors have mostly been tested on corpus data and have not yet been studied in combination. In two experiments, we therefore investigated the combined effects of interactive alignment and lexical triggering on code-switching. In Experiment 1, Dutch-English bilinguals described pictures to each other in a dialogue game where a confederate’s code-switching was manipulated. The participants were free to use either Dutch, English, or a combination of Dutch and English in describing the pictures, so they could voluntarily code-switch or not. The pictures contained a cognate [e.g., roos (rose)], a false friend [e.g., rok (skirt, false friend with rock)], or a control word [e.g., jas (coat)]. Participants code-switched more often when the confederate had just code-switched (indicating interactive alignment). They also code-switched more often when cognates were involved, but only when the confederate had just code-switched. This indicates that lexical triggering is driven by interactive alignment. False friends did not enhance the likelihood of code-switching. Experiment 2 used a similar dialogue game with participants from the same population but focused specifically on how to account for interactive alignment of code-switching. Rather than aligning on their dialogue partner’s pragmatic act of code-switching, bilinguals aligned on the language activation from the utterance produced by their dialogue partner. All in all, the results show how co-activation of languages at multiple levels of processing together influence bilinguals’ tendency to code-switch. The findings call for a perspective on bilingual language production in which cross-speaker and cross-language processes are combined.