Language Switching Task Research Articles

Transcranial magnetic stimulation of the right inferior frontal gyrus impairs bilinguals' performance in language-switching tasks

It is widely accepted that bilinguals activate both languages simultaneously, even when intending to speak only one. A prevailing theory proposes that bilinguals inhibit the nontarget language to produce the target language, thought to be supported by evidence that the right inferior frontal gyrus (rIFG), a region typically associated with inhibition, is activated during language-switching tasks. However, it remains unclear whether the rIFG plays a causal or epiphenomenal role in this process. To explore the role of the rIFG, the present study employed transcranial magnetic stimulation (TMS) to modulate its neural activity and evaluate subsequent behavior in bilinguals. Specifically, twenty-nine Chinese-English bilinguals participated in the study and performed picture-naming tasks in single- and dual-language contexts after receiving sham stimulation (Sham), continuous theta burst stimulation (cTBS), or intermittent theta burst stimulation (iTBS) over the rIFG in three separate visits. Sham served as a control, with cTBS and iTBS intended to decrease and increase cortical excitability, respectively. We found that, compared to Sham, cTBS led to larger asymmetric switching costs and smaller asymmetric mixing costs, whereas iTBS resulted only in smaller asymmetric mixing costs. These findings suggest that cTBS targeting the rIFG likely impairs both local and global control. However, iTBS applied to the rIFG alone may not necessarily enhance language control mechanisms and could even hinder global control. Moreover, exploratory analyses found pronounced TMS-induced impairments in less balanced bilinguals, implying their potentially greater reliance on bilingual language control. Overall, this study is the first to suggest a causal role of the rIFG in language switching.

Examining sources of language production switch costs amongst Tibetan-Chinese-English trilinguals

ABSTRACT The present study tested whether the switch costs of production-based language switching tasks by trilinguals are due to competition from outside language schemas or from within language systems. We recruited 90 Tibetan-Chinese-English trilinguals in 10th grade in a Tibetan middle school in China to name digits and number words using different stimuli valence. The study was divided into three experiments, one for each combination of two languages possible amongst Tibetan, Chinese and English. We observed the switch cost symmetrical patterns in the three experiments. The results suggest that the sources of switch cost are partially from outside competition between language schemas and partially from within language system. These results may contribute to our understanding of the language control mechanism between production-based and comprehension-based language switching tasks and language control mechanism of trilinguals with three orthographically different languages.

Modality-general and modality-specific bilingual control mechanisms in spoken and written productions

Abstract Do bilinguals have similar bilingual control mechanisms in speaking and writing? The present study investigated the patterns of switch costs (reflecting reactive language control) and mixing costs (reflecting proactive language control) between Chinese (L1) and English (L2) in spoken and written productions and whether these patterns could be modulated by response-stimulus intervals (RSIs). In two experiments, unbalanced Chinese–English bilinguals completed a cued language switching task in spoken naming (Experiment 1) and written naming (Experiment 2), respectively. The results revealed asymmetrical switch costs (i.e., the larger cost in L1 than in L2) in spoken and written productions in the short RSI condition. However, there were asymmetrical mixing costs in spoken production and symmetrical mixing costs in written production both in the short and long RSIs. These findings suggest that for spoken and written productions, reactive language control operates in similar mechanisms, while proactive language control operates in specific mechanisms.

Proactive and reactive language control in bilingual language production revealed by decoding sustained potentials and electroencephalography oscillations.

Adopting highly sensitive multivariate electroencephalography (EEG) and alpha-band decoding analyses, the present study investigated proactive and reactive language control during bilingual language production. In a language-switching task, Chinese-English bilinguals were asked to name pictures based on visually presented cues. EEG and alpha-band decoding accuracy associated with switch and non-switch trials were used as indicators for inhibition over the non-target language. Multivariate EEG decoding analyses showed that the decoding accuracy in L1 but not in L2, was above chance level shortly after cue onset. In addition, alpha-band decoding results showed that the decoding accuracy in L1 rose above chance level in an early time window and a late time window locked to the stimulus. Together, these asymmetric patterns of decoding accuracy indicate that both proactive and reactive attentional control over the dominant L1 are exerted during bilingual word production, with a possibility of overlap between two control mechanisms. We addressed theoretical implications based on these findings for bilingual language control models.

Language switching when writing: The role of phonological and orthographic overlap.

While language switching of bilinguals has been investigated extensively in the spoken domain, there has been little research on switching while writing. The factors that impact written language switching may differ from those that impact language switching while speaking. Thus, the study's goal was to test to what extent phonological and/or orthographic overlap impacts written language switching. In four experiments (NExp.1 = 34; NExp. 2 = 57; NExp. 3 = 39; NExp. 4 = 39), German-English bilinguals completed a cued language switching task where responses had to be typed. To-be-named translation-equivalent concepts were selected to be similar phonologically, orthographically or neither. Participants switching between languages while writing was facilitated by both phonological and orthographic overlap. Maximum orthographic overlap between translation-equivalent words with dissimilar pronunciations facilitated switching to the extent that no switch costs could be observed. These results imply that overlapping orthography can strongly facilitate written language switching and that orthography's role should be considered more thoroughly in models of bilingual language production.

The dynamic role of inhibitory control in language switching during number-word task performance in dominant and balanced bilinguals.

Language is one of the fascinating abilities of the human species. The beauty of language becomes intriguing when we examine language processing among bilinguals. This work attempted to study the effects of language dominance among native Hindi speakers who were either Hindi dominant, English dominant, or balanced bilingual in a language switching task. The task required the participants to read aloud the number-words that were presented singly on the computer screen. The findings support the inhibitory control model's predictions as the results were indicative of asymmetrical switch cost for both the Hindi and English dominant bilinguals. In both the language dominance condition, moving back to the dominant language from a non-dominant language required more time than vice versa. The results also indicated overall reduced reaction time in the reading task performance for balanced bilinguals, further demonstrating the benefits of balanced bilingualism.

Examining non-task language effect on production-based language switching: Evidence from Tibetan-Chinese-English trilinguals

Aims and objectives/purpose/research questions: This study examined the non-task language effect in production-based language switching tasks by trilinguals using two of their languages. Non-task language refers to one of the languages of the trilinguals that is not used in a two-language switching task. Design/methodology/approach: Tibetan-Chinese-English participants (11th-grade high school students with a median age of 17) were recruited to perform picture naming tasks in three experiments, each with a different language pair of the trilinguals’ three languages (i.e., L1–L2, L2–L3, L1–L3). For each experiment, there were two groups of participants (30 for each group) with comparable proficiency in the two task languages but with significantly contrasted proficiency levels of the non-task language. Data and analysis: Each participant performed 216 trials and all together over 10,000 trials were used in the analysis of either the response times or the error rates in each experiment. Data of response times were analysed using linear mixed-effect models and data of error rates were analysed using logistic mixed models. Findings/conclusions: The response times and the error rates data across the three experiments revealed no main effect of non-task language proficiency, indicating a null effect of the non-task language. We proposed that a proactive language control mechanism might be used to overcome the interference from the non-task language. Originality: The non-task language effect in trilingual language switching is a rarely discussed topic. Significance/implications: This study is meaningful in evaluating the degree of generalizability of previous studies and can help gain insight into the underlying mechanisms of trilinguals’ language control.

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.

Comprehension-based language switching between newly learned languages: The role of individual differences

The Adaptive Control hypothesis and relevant empirical evidence in bilingualism literature have revealed the adaptive nature of bilingual language control in skilled languages, while the language control processes at the very initial stage of new language learning have not been examined. The present study investigated how the individual differences in inhibition ability and language switching experience influence the controlling process of newly learned languages, using event related potentials (ERPs) technology. We first assessed the language switching frequency and inhibition ability of Chinese-English bilinguals on Day 1. Then, all bilinguals learned words from new languages (namely German and Japanese words) during the next six days and completed a comprehension-based language switching task between the newly learned languages on Day 8. Results of mixed-effects models on the behavioral data showed that there were no switching costs (i.e., derived by contrasting switch trials with repeat trials) and no predictive effect of individual difference on the language switching between newly learned languages. However, the ERPs results revealed switching costs and individual difference effects in N2 and LPC. The language switching frequency significantly predicted the variability of the N2 and LPC, and the inhibition ability modulated the switch effect in Japanese as showed in the LPC. These findings suggest that individual differences predict comprehension-based language control between the newly learned languages, providing new evidence for the adaptability of language control from a language comprehension perspective.

Language control in regional dialect speakers – monolingual by name, bilingual by nature?

AbstractWhile 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.

Overlapping but Language-Specific Mechanisms in Morphosyntactic Processing in Highly Competent L2 Acquired at School Entry: fMRI Evidence From an Alternating Language Switching Task.

Many bilingual individuals acquire their second language when entering primary school; however, very few studies have investigated morphosyntax processing in this population. Combining a whole-brain and region of interest (ROI)-based approach, we studied event-related fMRI during morphosyntactic processing, specifically person-number phi-features, in Turkish (L1) and Persian (L2) by highly proficient bilinguals who learned Persian at school entry. In a design with alternating language switching and pseudorandomized grammaticality conditions, two left-lateralized syntax-specific ROIs and 11 bilateral ROIs involved in executive functions (EF) were analyzed for the intensity of activation relative to a resting baseline. Our findings indicate a strong overlap of neural networks for L1 and L2, suggesting structural similarities of neuroanatomical organization. In all ROIs morphosyntactic processing invoked stronger activation in L1 than in L2. This may be a consequence of symmetrical switch costs in the alternating design used here, where the need for suppressing the non-required language is stronger for the dominant L1 when it is non-required as compared to the non-dominant L2, leading to a stronger rebound for L1 than L2 when the language is required. Both L1 and L2 revealed significant activation in syntax-specific areas in left hemisphere clusters and increased activation in EF-specific areas in right-hemisphere than left-hemisphere clusters, confirming syntax-specific functions of the left hemisphere, whereas the right hemisphere appears to subserve control functions required for switching languages. While previous reports indicate a leftward bias in planum temporale activation during auditory and linguistic processing, the present study shows the activation of the right planum temporale indicating its involvement in auditory attention. More pronounced grammaticality effect in left pars opercularis for L1 and in left pSTG for L2 indicate differences in the processing of morphosyntactic information in these brain regions. Nevertheless, the activation of pars opercularis and pSTG emphasize the centrality of these regions in the processing of person-number phi-features. Taken together, the present results confirm that morphosyntactic processing in bilinguals relates to composite, syntax-sensitive and EF-sensitive mechanisms in which some nodes of the language network are differentially involved.

Older bilinguals reverse language dominance less than younger bilinguals: Evidence for the inhibitory deficit hypothesis.

Inhibitory control is thought to play a key role in how bilinguals switch languages and may decline in aging. We tested these hypotheses by examining age group differences in the reversed language dominance effect-a signature of inhibition of the dominant language that leads bilinguals to name pictures more slowly in the dominant than the nondominant language in mixed-language testing blocks. Twenty-five older and 48 younger Spanish-English bilinguals completed a cued language-switching task. To test if inhibition is applied at the whole-language or lexical level, we first presented one set of pictures repeatedly, then introduced a second list halfway through the experiment. Younger bilinguals exhibited significantly greater reversed language dominance effects than older bilinguals (who exhibited nonsignificant language dominance effects). In younger bilinguals, dominance reversal transferred to, and was even larger in, the second list (compared to the first). The latter result may suggest that inhibition is partially offset by repetition in ways that are not yet fully understood. More generally, these results support the hypotheses that aging impairs inhibitory control of the dominant language, which young bilinguals rely on to switch languages. Additionally, inhibition is applied primarily at the whole-language level, and speculatively, this form of language control may be analogous to nonlinguistic proactive control. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

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.

Do All Switches Cost the Same? Reliability of Language Switching and Mixing Costs.

The current study examined the reliability and consistency of switching and mixing costs in the language and the color-shape tasks in three pre-existing data sets, to assess whether they are equally well suited for the study of individual differences. Specifically, we considered if the language task is as reliable as the color-shape task – an important question given the wide use of language switching tasks but little information available to address this question. Switching costs had low to moderate reliability and internal consistency, and these were similar for the language and the color-shape tasks. Mixing costs were more reliable in the language task than in the color-shape task when tested twice on the same day and trended in the same direction when tested a week apart. In addition, mixing costs were larger and more consistent than switching costs in all data sets and they were also were more reliable than switching costs in the language task when tested on the same day. These results reveal the language task to be as good as the color-shape task for measuring switching and mixing ability. Low variability of switching costs may decrease their reliability and consistency, in turn interfering with the chance of detecting cross task correlations. We advocate for exploring procedures to increase the variability of switching costs, which might increase reliability and consistency of these measures, and improve the ability to determine if bilingual language use relies on cognitive mechanisms that overlap with those underlying nonlinguistic multi-tasking.

Different inhibitory control components predict different levels of language control in bilinguals

In recent years, some studies have started to explore the impact of individual general executive functions (EFs) on bilingual language control. To our knowledge, few studies have systematically examined various components of EFs on different levels of language control in bilinguals. In two experiments, we investigated the effects of two components of IC on different levels of bilingual language control. The language-switching task was used to tap into language control at different levels. The Simon task was used to measure interference suppression in Experiment 1, and a go/no-go task was used to measure response inhibition in Experiment 2. Experiment 1 found that the smaller the Simon effect was, the larger the asymmetry of switch costs was. Experiment 2 found that the shorter the go response time was, the larger the global slowing effect was. Taken together, these findings suggest that the interference suppression component of domain-general IC facilitates local level language control, while response inhibition impacts global level language control in bilinguals.

Language Differentiation Using Augmentative and Alternative Communication: An Investigation of Spanish-English Bilingual Children With and Without Language Impairments.

Purpose Children with severe speech and language impairments growing up in dual language environments may communicate in more than one language using augmentative and alternative communication (AAC). This study investigated predictors of bilingual children's ability to differentiate between Spanish and English using an AAC iPad app during a cued language-switching task and examined whether switching between languages using AAC incurred a cognitive cost. Method Participants were 58 Spanish-English bilingual children ages 4;0-6;11 (years;months; 23 with language impairments). Children received standardized language and cognitive assessments and completed an experimental language-switching task in which they were asked to differentiate between languages using an AAC iPad app containing English and Spanish vocabulary layouts paired with voice output. Results Results of a binary logistic regression indicated that, when controlling for age, processing speed significantly predicted whether children were classified as high or low performers on the experimental task. Nonparametric tests indicated that switching between languages did not incur a cognitive cost as evidenced by similar response times on trials where participants were required to switch between languages compared to trials where they did not switch. Conclusion This study contributes to the understanding of how young bilingual children with and without language impairments conceptualize and discriminate between languages represented in a visual-graphic modality paired with speech output. Supplemental Material https://doi.org/10.23641/asha.13289330.

Language control network adapts to second language learning: A longitudinal rs-fMRI study

The current longitudinal resting-state functional magnetic resonance imaging study examined changes in language control network after one year of L2 English classroom learning. A group of Chinese college freshmen majoring in English underwent two scans, one before (i.e., Session 1) and one after (i.e., Session 2) the one-year L2 courses. Learners' language control abilities were assessed via a behavioral language switching task. Our graph theory and functional connectivity analyses revealed that with increased exposure to the L2, nodal betweenness in language control areas, such as the dorsal anterior cingulate cortex (dACC), decreased and connectivity between dACC and pre-supplementary motor area (pre-SMA) increased. Critically, these neural changes were correlated with participants' behavioral performance on the language switching task. Taken together, these findings suggest that the language control network in resting brain could be modulated by long-term L2 learning in a naturalistic classroom setting, and that the dACC/pre-SMA complex appears to play a critical role in language control.

Voluntary Language Switching in the Context of Bilingual Aphasia.

As studies of bilingual language control (BLC) seek to explore the underpinnings of bilinguals’ abilities to juggle two languages, different types of language switching tasks have been used to uncover switching and mixing effects and thereby reveal what proactive and reactive control mechanisms are involved in language switching. Voluntary language switching tasks, where a bilingual participant can switch freely between their languages while naming, are being utilized more often due to their greater ecological validity compared to cued switching paradigms. Because this type of task had not yet been applied to language switching in bilingual patients, our study sought to explore voluntary switching in bilinguals with aphasia (BWAs) as well as in healthy bilinguals. In Experiment 1, we replicated previously reported results of switch costs and mixing benefits within our own bilingual population of Catalan-Spanish bilinguals. With Experiment 2, we compared both the performances of BWAs as a group and as individuals against control group performance. Results illustrated a complex picture of language control abilities, indicating varying degrees of association and dissociation between factors of BLC. Given the diversity of impairments in BWAs’ language control mechanisms, we highlight the need to examine BLC at the individual level and through the lens of theoretical cognitive control frameworks in order to further parse out how bilinguals regulate their language switching.

Dual Function of Primary Somatosensory Cortex in Cognitive Control of Language: Evidence from Resting State fMRI

Resting state functional connectivity can be leveraged to investigate bilingual individual differences in cognitive control of language; however, thus far no report is provided on how the connectivity profiles of brain functional networks at rest point to different language control behavior in bilinguals. In order to address this gap in state-of-the-art research we did a functional connectivity analysis on the resting state data acquired via multiband EPI to investigate three resting state networks of interest namely, the frontoparietal network (FPN), the salience network (SN), and the default mode network (DMN), which are related to cognitive control, between two groups of Dutch–English bilinguals based on how they performed in a language switching task. Results demonstrated that there is the increased coupling of the left primary somatosensory cortex with the dorsolateral prefrontal cortex in the group with better performance in cognitive control of language and the increased coupling of the right primary somatosensory cortex with the inferior parietal cortex in the group with poorer performance in this executive function. As regards these results, we claim that the primary somatosensory cortex has a dual function in coupling with the dorsolateral prefrontal cortex and the inferior parietal cortex in the FPN, and in fact, in what characterizes bilingual individual differences in cognitive control of language in healthy participants. The results of this study provide a model for future research in cognitive control of language and may serve as a reference in clinical neuroscience when bilinguals are diagnosed with dysfunction in cognitive control.

Whole-Language and Item-Specific Inhibition in Bilingual Language Switching: The Role of Domain-General Inhibitory Control.

A prominent theory of bilingual speech production holds that appropriate language selection is achieved via inhibitory control. Such inhibition may operate on the whole-language and/or item-specific level. In this study, we examined these two levels of control in parallel, by introducing a novel element into the traditional cued language switching paradigm: half of the stimuli were univalent (each required naming in the same language every time it appeared), and the other half were bivalent (each required naming in different languages on different trials). Contrasting switch and stay trials provided an index for whole-language inhibition, while contrasting bivalent and univalent stimuli provided an index for item-specific inhibition. We then investigated the involvement of domain-general brain mechanisms in these two levels of language control. Neuroimaging studies report activation of the pre-supplementary motor area (pre-SMA), a key region in the executive control brain network, during language switching tasks. However, it is unclear whether or not the pre-SMA plays a causal role in language control, and at which level it exerts control. Using repetitive transcranial magnetic stimulation (TMS) to transiently disrupt the pre-SMA, we observed an essential role of this brain region in general speech execution, while evidence for its specific involvement in each level of inhibition remains inconclusive.