Bilingual Language Switching in the Laboratory versus in the Wild: The Spatiotemporal Dynamics of Adaptive Language Control

Parallel Interactions Between Linguistic and Contextual Factors in Bilinguals

The necessity for introducing interactionist and parallelism approaches in different branches of cognitive science emerged as a reaction to classical sequential stage-based models. Functional psychological models that emphasized and explained how different components interact, dynamically producing cognitive and perceptual states, influenced multiple disciplines. Chiefly among them were experimental psycholinguistics and the many applied areas that dealt with humans' ability to process different types of information in different contexts. Understanding how bilinguals represent and process verbal and visual input, how their neural and psychological states facilitate such interactions, and how linguistic and nonlinguistic processing overlap, has now emerged as an important area of multidisciplinary research. In this article, we will review available evidence from different language-speaking groups of bilinguals in India with a focus on situational context. In the discussion, we will address models of language processing in bilinguals within a cognitive psychological approach with a focus on existent models of inhibitory control. The paper's stated goal will be to show that the parallel architecture framework can serve as a theoretical foundation for examining bilingual language processing and its interface with external factors such as social context.

Tracking Components of Bilingual Language Control in Speech Production: An fMRI Study Using Functional Localizers

When bilingual speakers switch back to speaking in their native language (L1) after having used their second language (L2), they often experience difficulty in retrieving words in their L1. This phenomenon is referred to as the L2 after-effect. We used the L2 after-effect as a lens to explore the neural bases of bilingual language control mechanisms. Our goal was twofold: first, to explore whether bilingual language control draws on domain-general or language-specific mechanisms; second, to investigate the precise mechanism(s) that drive the L2 after-effect. We used a precision fMRI approach based on functional localizers to measure the extent to which the brain activity that reflects the L2 after-effect overlaps with the language network (Fedorenko et al., 2010) and the domain-general multiple demand network (Duncan, 2010), as well as three task-specific networks that tap into interference resolution, lexical retrieval, and articulation. Forty-two Polish-English bilinguals participated in the study. Our results show that the L2 after-effect reflects increased engagement of domain-general but not language-specific resources. Furthermore, contrary to previously proposed interpretations, we did not find evidence that the effect reflects increased difficulty related to lexical access, articulation, and the resolution of lexical interference. We propose that difficulty of speech production in the picture naming paradigm-manifested as the L2 after-effect-reflects interference at a nonlinguistic level of task schemas or a general increase of cognitive control engagement during speech production in L1 after L2.

Multilingualism at the Market: A Pre-registered Immersive Virtual Reality Study of Bilingual Language Switching

Bilinguals, by definition, are capable of expressing themselves in more than one language. But which cognitive mechanisms allow them to switch from one language to another? Previous experimental research using the cued language-switching paradigm supports theoretical models that assume that both transient, reactive and sustained, proactive inhibitory mechanisms underlie bilinguals' capacity to flexibly and efficiently control which language they use. Here we used immersive virtual reality to test the extent to which these inhibitory mechanisms may be active when unbalanced Dutch-English bilinguals i) produce full sentences rather than individual words, ii) to a life-size addressee rather than only into a microphone, iii) using a message that is relevant to that addressee rather than communicatively irrelevant, iv) in a rich visual environment rather than in front of a computer screen. We observed a reversed language dominance paired with switch costs for the L2 but not for the L1 when participants were stand owners in a virtual marketplace and informed their monolingual customers in full sentences about the price of their fruits and vegetables. These findings strongly suggest that the subtle balance between the application of reactive and proactive inhibitory mechanisms that support bilingual language control may be different in the everyday life of a bilingual compared to in the (traditional) psycholinguistic laboratory.

Dual-tasking while using two languages: Examining the cognitive resource demands of cued and voluntary language production in bilinguals

The way bilinguals switch languages can differ depending on the context. In cued dual-language environments, bilinguals select a language in response to environmental cues (e.g., a monolingual conversation partner). In voluntary dual-language environments, bilinguals communicating with people who speak the same languages can use their languages more freely. The control demands of these types of language-production contexts, and the costs of language switches, have been argued to differ (Adaptive Control Hypothesis). Here, we used a dual-task paradigm to examine how cued and voluntary bilingual production differ in cognitive resources used. Forty Mandarin-English bilinguals completed two language-switching paradigms as the primary task; one in response to cues and one while using two languages freely. At the same time, they also had to respond to the pitch of tones (secondary task). Response times (RTs) on the secondary task, as well as naming times on the primary task, were shorter under the voluntary- than cued-naming condition. Task workload ratings were also higher under the cued- than voluntary-naming condition. This suggests more attentional resources are needed in a cued-naming context to monitor cues and select languages accordingly. However, the costs associated with switching from one language to the other were similar in both voluntary- and cued-naming contexts. Thus, while cued-naming might be more effortful overall, cued and voluntary switching recruited similar levels of cognitive resources.

The role of minority language bilingualism in spotting agreement attraction errors: Evidence from Italian varieties

Bilingual adaptations remain a subject of ongoing debate, with varying results reported across cognitive domains. A possible way to disentangle the apparent inconsistency of results is to focus on the domain of language processing, which is what the bilingual experience boils down to. This study delves into the role of the bilingual experience on the processing of agreement mismatches. Given the underrepresentation of minority bilingual speakers of non-standard varieties, we advance a unique comparative perspective that includes monolinguals, standard language bilinguals, and different groups of minority language bilinguals, taking advantage of the rich linguistic diversity of the Italian peninsula. This comparative approach can reveal the impact of various sociolinguistic aspects of the bilingual experience across different bilingual trajectories. We developed an auditory acceptability judgement task in Italian, featuring Subject-Verb agreement mismatches. Participants evaluated the stimuli on a 5-point Likert scale and reaction times were recorded. The results do not reveal significant differences between the speakers of standard languages: Italian monolinguals and Italian-Spanish bilinguals. Instead, significant differences are found between monolinguals and the two groups of minority language bidialectals, as well as between the bidialectal groups themselves: Italian-Pavese bidialectals were faster than both Italian-Agrigentino bidialectals and Italian monolinguals, while Italian-Agrigentino bidialectals were less accurate than both Italian-Pavese bidialectals and Italian monolinguals. This intricate picture is explained through variables associated with second language use and language switching. Our findings suggest that if bilingualism is viewed as a yes/no phenotype, it is unavoidable that the bilingual experience will remain a mystery linked to intensely debated results. If, however, one accepts that bilingual adaptations are shaped by the environmental ecology of each trajectory, variation across bilingual processing outcomes is unsurprising. Overall, we argue that specific sociolinguistic factors behind each bilingual experience can reveal where bilingual adaptations on language and cognition stem from.

Cognitive and neural mechanisms of voluntary versus forced language switching in Chinese-English bilinguals: an fMRI study

The ecological validity of bilingual code-switching has garnered increasing attention in recent years. Contrary to traditional studies that have focused on forced language switching, emerging theories posit that voluntary switching may not incur such a cost. To test these claims and understand differences between forced and voluntary switching, the present study conducted a systematic comparison through both behavioral and neural perspectives. Utilizing fMRI alongside picture-naming tasks, our findings diverge from prior work. Voluntary language switching not only demonstrated switching costs at the behavioral level but also significantly activated brain regions associated with inhibitory control. Direct comparisons of voluntary and forced language switching revealed no significant behavioral differences in switching costs, and both shared several common brain regions that were activated. On the other hand, a nuanced difference between the two types of language switching was revealed by whole-brain analysis: voluntary switching engaged fewer language control regions than forced switching. These findings offer a comprehensive view of the neural and behavioral dynamics involved in bilingual language switching, challenging prior claims that voluntary switching imposes no behavioral or neural costs, and thus providing behavioral and neuroimaging evidence for the involvement of inhibitory control in voluntary language switching.

Beyond the tried and true: How virtual reality, dialog setups, and a focus on multimodality can take bilingual language production research forward

Bilinguals possess the ability of expressing themselves in more than one language, and typically do so in contextually rich and dynamic settings. Theories and models have indeed long considered context factors to affect bilingual language production in many ways. However, most experimental studies in this domain have failed to fully incorporate linguistic, social, or physical context aspects, let alone combine them in the same study. Indeed, most experimental psycholinguistic research has taken place in isolated and constrained lab settings with carefully selected words or sentences, rather than under rich and naturalistic conditions. We argue that the most influential experimental paradigms in the psycholinguistic study of bilingual language production fall short of capturing the effects of context on language processing and control presupposed by prominent models. This paper therefore aims to enrich the methodological basis for investigating context aspects in current experimental paradigms and thereby move the field of bilingual language production research forward theoretically. After considering extensions of existing paradigms proposed to address context effects, we present three far-ranging innovative proposals, focusing on virtual reality, dialog situations, and multimodality in the context of bilingual language production.

Different language control mechanisms in comprehension and production: Evidence from paragraph reading

Chinese-English bilinguals read paragraphs with language switches using a rapid serial visual presentation paradigm silently while ERPs were measured (Experiment 1) or read them aloud (Experiment 2). Each paragraph was written in either Chinese or English with several function or content words switched to the other language. In Experiment 1, language switches elicited an early, long-lasting positivity when switching from the dominant language to the nondominant language, but when switching to the dominant language, the positivity started later, and was never larger than when switching to the nondominant language. In addition, switch effects on function words were not significantly larger than those on content words in any analyses. In Experiment 2, participants produced more cross-language intrusion errors when switching to the dominant than to the nondominant language, and more errors on function than content words. These results implicate different control mechanisms in bilingual language selection across comprehension and production.

Combining Languages in Bilingual Input: Using Experimental Evidence to Formulate Bilingual Exposure Strategies

PURPOSE

Traditional approaches to studying bilingual language development through bilingual-monolingual comparisons are deeply flawed. They are also insufficient as the evidence base for informing advice to bilingual parents regarding the optimal bilingual exposure strategy and for supporting the formulation of bilingual intervention approaches. The purpose of this review article is to provide an overview of empirical studies that have queried the question of how different types of dual-language input shape learning and language outcomes in bilingual children.

METHOD

We rely on tightly controlled experimental studies of word learning in Spanish-English bilingual children, where we contrast children's learning in dual-language conditions (defined as distributed exposure and code-switched input) to a single-language condition in a within-subjects design.

RESULTS

Word-learning studies querying the role of distributed exposure indicated that distribution of exposures across Spanish and English reduced children's performance in comparison to English-only exposure. However, this effect was rooted in the abrupt switch from Spanish to English rather than distributed exposure itself. In contrast, an experiment designed to test the role of code-switched context on children's word learning revealed that code-switched context where switches resembled naturalistic code-switching behaviors enhanced learning in Spanish-English bilingual children. Notably, across different studies, children with weaker language skills (developmental language disorder) were no more affected by dual-language input than children with typical language skills.

CONCLUSIONS

Together, experimental studies of word learning indicate that bilingual children can effectively learn from dual-language input but that different ways of combining languages in the input to bilingual children can have distinct consequences for learning. Ultimately, word-learning experiments, beyond answering critical questions regarding bilingual learning, can serve as an effective bridge between laboratory-based work and intervention studies whose goal it is to discover the optimal way of combining languages in the input to bilingual children with communication impairments.

PRESENTATION VIDEO

https://doi.org/10.23641/asha.23929515.

Inhibitory control of the dominant language: Reversed language dominance is the tip of the iceberg

Theories of speech production have proposed that in contexts where multiple languages are produced, bilinguals inhibit the dominant language with the goal of making both languages equally accessible. This process often overshoots this goal, leading to a surprising pattern: better performance in the nondominant vs. dominant language, or reversed language dominance effects. However, the reliability of this effect in single word production studies with cued language switches has been challenged by a recent meta-analysis. Correcting for errors in this analysis, we find that dominance effects are reliably reduced and reversed during language mixing. Reversed dominance has also consistently been reported in the production of connected speech elicited by reading aloud of mixed language paragraphs. When switching, bilinguals produced translation-equivalent intrusion errors (e.g., saying pero instead of but) more often when intending to produce words in the dominant language. We show this dominant language vulnerability is not exclusive to switching out of the nondominant language and extends to non-switch words, linking connected speech results to patterns first reported in single word studies. Reversed language dominance is a robust phenomenon that reflects the tip of the iceberg of inhibitory control of the dominant language in bilingual language production.

How processing emotion affects language control in bilinguals

Research has shown that several variables affect language control among bilingual speakers but the effect of affective processing remains unexplored. Chinese-English bilinguals participated in a novel prime-target language switching experiment in which they first judged the affective valence (i.e., positive or negative) of auditorily presented words and then named pictures with neutral emotional valence in either the same (non-switch trial) or different language (switch trial). Brain activity was monitored using functional magnetic resonance imaging (fMRI). The behavioral performance showed that the typical switch cost (i.e., the calculated difference between switch and non-switch trials) emerged after processing positive words but not after negative words. Brain imaging demonstrated that processing negative words immediately before non-switch picturing naming trials (but not for switch trials) increased activation in brain areas associated with domain-general cognitive control. The opposite patterns were found after processing positive words. These findings suggest that an (emotional) negative priming effect is induced by spontaneous exposure to negative words and that these priming effects may be triggered by reactive emotional processing and that they may interact with higher level cognitive functions.

Cost or advantage? Intra-sentential language switching could facilitate L2 emotional words' comprehension in auditory modality

Language switching is encountered commonly and inevitably in bilingual society and often induces costs for target language's production. However, for auditory words' comprehension at sentence level, the limited research showed divergent findings. Some research observed comprehension costs when the language of target words was switched with the code of sentential contexts kept constant; but a potential switch advantage was also showed in non-dominant targets' processing when sentential context switches occurred. Additionally, it's well documented that the words' emotional connotations play a key role in both L1 and L2 word comprehension. Therefore, we aimed to explore which switch effect would occur when bilinguals comprehended L1/L2 emotional target nouns in auditory modality at behavioral and neural level through a visual object selection task. Behaviorally, switch related costs occurred in L1 targets' comprehension, whereas advantage effects were found in L2. Moreover, greater switch advantage occurred for positive and negative targets than for neutral ones. Consistently, larger LPC (Late Positive Component) defection was elicited for L2-Switch trials relative to L2-Nonswitch trials and the differences of LPC's amplitude could predict the behavioral advantageous effects of switching in nondominant targets' comprehension, which suggest that language switching lead to deeper re-analyses for emotional words. Taken together, it's suggested that bilinguals can adaptively utilize top-down (sentential prediction) and bottom-up (words' emotional information) cues to access weaker L2 representations.

Neural circuits underlying language control and modality control in bilinguals: An fMRI study

Human communication not only involves the need to switch between the modalities of speaking and listening, but for bilinguals, it can also involve switching between languages. It is unknown as to whether modality and language switching share underlying control mechanisms or whether one type of switching affects control processes involved in the other. The present study uses behavioral and fMRI measures to examine neural circuits of control during communicative situations that required Chinese-English bilinguals to switch between modalities and their two languages according to associated color cues. The results showed that for both language and modality control, similar brain regions were recruited during speech production and comprehension. For modality control, the specific control processes partly depended on the corresponding modality. Finally, switching between modalities appears to exert more influence on language control in production compared to comprehension. These findings offer a first detailed characterization of the neural bases involved in control mechanisms in bilingual communication.

No evidence for a mixing benefit-A registered report of voluntary dialect switching

Previous language production research with bidialectals has provided evidence for similar language control processes as during bilingual language production. In the current study, we aimed 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. While the bidialectals in this study also showed symmetrical switch costs, no mixing effect was observed. These results could be taken as evidence that bidialectal and bilingual language control are not entirely similar.

Oscillatory brain responses to processing code-switches in the presence of others

Code-switching, i.e. the alternation between languages in a conversation, is a typical, yet socially-constrained practice in bilingual communities. For instance, code-switching is permissible only when other conversation partners are fluent in both languages. Studying code-switching provides insight in the cognitive and neural mechanisms underlying language control, and their modulation by linguistic and non-linguistic factors. Using time-frequency representations, we analyzed brain oscillation changes in EEG data recorded in a prior study (Kaan et al., 2020). In this study, Spanish-English bilinguals read sentences with and without switches in the presence of a bilingual or monolingual partner. Consistent with prior studies, code-switches were associated with a power decrease in the lower beta band (15-18 Hz). In addition, code-switches were associated with a power decrease in the upper gamma band (40-50 Hz), but only when a bilingual partner was present, suggesting the semantic/pragmatic processing of code-switches differs depending on who is present.

Event-related responses reflect chunk boundaries in natural speech

Chunking language has been proposed to be vital for comprehension enabling the extraction of meaning from a continuous stream of speech. However, neurocognitive mechanisms of chunking are poorly understood. The present study investigated neural correlates of chunk boundaries intuitively identified by listeners in natural speech drawn from linguistic corpora using magneto- and electroencephalography (MEEG). In a behavioral experiment, subjects marked chunk boundaries in the excerpts intuitively, which revealed highly consistent chunk boundary markings across the subjects. We next recorded brain activity to investigate whether chunk boundaries with high and medium agreement rates elicit distinct evoked responses compared to non-boundaries. Pauses placed at chunk boundaries elicited a closure positive shift with the sources over bilateral auditory cortices. In contrast, pauses placed within a chunk were perceived as interruptions and elicited a biphasic emitted potential with sources located in the bilateral primary and non-primary auditory areas with right-hemispheric dominance, and in the right inferior frontal cortex. Furthermore, pauses placed at stronger boundaries elicited earlier and more prominent activation over the left hemisphere suggesting that brain responses to chunk boundaries of natural speech can be modulated by the relative strength of different linguistic cues, such as syntactic structure and prosody.

Control mechanisms in voluntary versus mandatory language switching: Evidence from ERPs

The present study measured event-related potentials (ERP) and behavioral performance to examine whether inhibitory control is involved in voluntary language switching, and if so, to explore the differences in inhibitory control between voluntary and mandatory language switching. Unbalanced Chinese-English bilinguals completed two picture naming tasks: one involving mandatory language switches and one in which participants could voluntarily switch between the two languages. Behavioral data showed significant switch costs and a reversed language dominance effect in both switching tasks. Critically, both effects were larger in mandatory compared to voluntary switching. ERP results revealed that neural switch costs during mandatory switching was significantly different than voluntary switching in both N2 and LPC amplitudes. In contrast, a significant difference in the reversed language dominance effect between both tasks was only observed in LPC amplitude. Together, these findings suggest the involvement of inhibitory control in both mandatory and voluntary language switching, but the degree of inhibition and the time-course of control processes between both tasks appear to be distinct.

Dynamic Effects of Immersive Bilingualism on Cortical and Subcortical Grey Matter Volumes

Bilingualism has been shown to induce neuroplasticity in the brain, but conflicting evidence regarding its specific effects in grey matter continues to emerge, probably due to methodological differences between studies, as well as approaches that may miss the variability and dynamicity of bilingual experience. In our study, we devised a continuous score of bilingual experiences and we investigated their non-linear effects on regional GM volume in a sample of young healthy participants from an immersive and naturalistic bilingual environment. We focused our analyses on cortical and subcortical regions that had been previously proposed as part of the bilingual speech pipeline and language control network. Our results showed a non-linear relationship between bilingualism score and grey matter volume of the inferior frontal gyrus. We also found linear increases in volumes of putamen and cerebellum as a function of bilingualism score. These results go in line with predictions for immersive and naturalistic bilingual environments with increased intensity and diversity of language use and provide further evidence supporting the dynamicity of bilingualism’s effects on brain structure.

Language-switch Costs from Comprehension to Production Might Just Be Task-switch Costs

Spanish-English bilinguals switched between naming pictures in one language and either reading-aloud or semantically classifying written words in both languages. When switching between reading-aloud and picture-naming, bilinguals exhibited no language switch costs in picture naming even though they produced overt language switches in speech. However, when switching between semantic classification and picture naming, bilinguals, especially unbalanced bilinguals, exhibited switch costs in the dominant language and switch facilitation in the nondominant language even though they never switched languages overtly. These results reveal language switching across comprehension and production can be cost-free when the intention remains the same. Assuming switch costs at least partially reflect inhibition of the nontarget language, this implies such language control mechanisms are recruited only under demanding task conditions, especially for unbalanced bilinguals. These results provide striking demonstration of adaptive control mechanisms and call into question previous claims that language switch costs necessarily transfer from comprehension to production.

Attentional orienting abilities in bilinguals: Evidence from a large infant sample

A key question in studies of cognitive development is whether bilingual environments impact higher-cognitive functions. Inconclusive evidence in search of a "bilingual cognitive advantage" has sparked debates on the reliability of these findings. Few studies with infants have examined this question, but most of them include small samples. The current study presents evidence from a large sample of 6- and 10-month-old monolingual- and bilingual-exposed infants (N = 152), which includes a longitudinal subset (n = 31), who completed a cueing attentional orienting task. The results suggest bilingual infants showed significant developmental gains in latency performance during the condition that was most cognitively demanding (Incongruent). The results also revealed bilingual infants' performance was associated with their parents' dual-language switching behavior. Taken together, these results provide support that bilingual experiences (i.e., dual-language mixing) influence infants' shifting and orienting of attention.

Natural vs forced language switching: Free selection and consistent language use eliminate significant performance costs and cognitive demands in the brain

Bilinguals are known to switch language spontaneously in everyday conversations, even if there are no external requirements to do so. However, in the laboratory setting, language control is often investigated using forced switching tasks, which result in significant performance costs. The present study assessed whether switching would be less costly when performed in a more natural fashion, and what factors might account for this. Mandarin-English bilinguals engaged in language switching under three different contexts with varied task demands. We examined two factors which may be characteristic of natural switching: (i) freedom of language selection; (ii) consistency of language used to name each item. Participants' brain activities were recorded using magnetoencephalography (MEG), along with behavioural measures of reaction speed and accuracy. The natural context (with both free selection and consistent language use for each item) produced better performance overall, showing reduced mixing cost and no significant switch cost. The neural effect of language mixing was also reversed in this context, suggesting that freely mixing two languages was easier than staying in a single language. Further, while switching in the forced context elicited increased brain activity in the right inferior frontal gyrus, this switch effect disappeared when the language used to name each item was consistent. Together, these findings demonstrate that the two factors above conjointly contribute to eliminating significant performance costs and cognitive demands associated with language switching and mixing. Such evidence aligns with lexical selection models which do not assume bilingual production to be inherently effortful.

Cross-Task Adaptation Effects of Bilingual Language Control on Cognitive Control: A Dual-Brain EEG Examination of Simultaneous Production and Comprehension

For bilinguals, speaking and listening are assisted by complex control processes including conflict monitoring and inhibition. However, the extent to which these processes adapt to linguistic and situational needs has been examined separately for language production and comprehension. In the present study, we use a dual-EEG to record the carry-over effects of language control on general cognitive control in three language contexts (single-first language [L1], single-second language [L2], and mixed). Chinese learners of English were placed in dyads in which one participant was asked to name pictures while the other listened. Interleaved after each naming/listening trial were flanker trials. The results from picture naming and listening revealed higher delta and theta synchronization in the single-L2 and mixed contexts compared with the single-L1 context and higher theta synchronization in the mixed context compared with the single-L2 and single-L1 contexts. The results from the interleaved flanker trials demonstrated that inhibition was adaptively generalized in the single-L2 and mixed contexts. Altogether, the findings support the natural adaptation of language control to cognitive control and underscore the importance of linguistic context. We argue that these adaptive patterns have the potential to affect corresponding control processes across language and cognitive control tasks.

Phasic pupillary responses reveal differential engagement of attentional control in bilingual spoken language processing

Language processing is cognitively demanding, requiring attentional resources to efficiently select and extract linguistic information as utterances unfold. Previous research has associated changes in pupil size with increased attentional effort. However, it is unknown whether the behavioral ecology of speakers may differentially affect engagement of attentional resources involved in conversation. For bilinguals, such an act potentially involves competing signals in more than one language and how this competition arises may differ across communicative contexts. We examined changes in pupil size during the comprehension of unilingual and codeswitched speech in a richly-characterized bilingual sample. In a visual-world task, participants saw pairs of objects as they heard instructions to select a target image. Instructions were either unilingual or codeswitched from one language to the other. We found that only bilinguals who use each of their languages in separate communicative contexts and who have high attention ability, show differential attention to unilingual and codeswitched speech. Bilinguals for whom codeswitching is common practice process unilingual and codeswitched speech similarly, regardless of attentional skill. Taken together, these results suggest that bilinguals recruit different language control strategies for distinct communicative purposes. The interactional context of language use critically determines attentional control engagement during language processing.

The source of attention modulations in bilingual language contexts

Bilinguals who switch from a monolingual context to a bilingual context enhance their domain-general attentional system. But what drives the adaptation process and translates into the observed increased efficiency of the attentional system? To uncover the origin of the plasticity in a bilingual's language experience, we investigated whether switching between other types of categories also modulated domain-general attentional processes. We compared performance of Catalan-Spanish bilinguals across three experiments in which participants performed the Attentional Network Test in a mixed context and in two single contexts that were created by interleaving words with flankers. The contexts were related to switching (or not) between languages (Experiment-1) or between low-level perceptual color categories (Experiment-2) or between linguistic categories (Experiment-3). Both switching between languages and linguistic categories revealed increased target-P3 amplitudes in mixed contexts compared to single contexts. These findings can inform the Inhibitory Control model regarding the locus and domain-generality of attentional adaptations.

Clear Theories Are Needed to Interpret Differences: Perspectives on the Bilingual Advantage Debate

The heated debate regarding bilingual cognitive advantages remains ongoing. While there are many studies supporting positive cognitive effects of bilingualism, recent meta-analyses have concluded that there is no consistent evidence for a bilingual advantage. In this article we focus on several theoretical concerns. First, we discuss changes in theoretical frameworks, which have led to the development of insufficiently clear theories and hypotheses that are difficult to falsify. Next, we discuss the development of looking at bilingual experiences and the need to better understand language control. Last, we argue that the move from behavioural studies to a focus on brain plasticity is not going to solve the debate on cognitive effects, especially not when brain changes are interpreted in the absence of behavioural differences. Clearer theories on both behavioural and neural effects of bilingualism are needed. However, to achieve this, a solid understanding of both bilingualism and executive functions is needed first.

Moving From Bilingual Traits to States: Understanding Cognition and Language Processing Through Moment-to-Moment Variation

The study of how bilingualism is linked to cognitive processing, including executive functioning, has historically focused on comparing bilinguals to monolinguals across a range of tasks. These group comparisons presume to capture relatively stable cognitive traits and have revealed important insights about the architecture of the language processing system that could not have been gleaned from studying monolinguals alone. However, there are drawbacks to using a group-comparison, or Traits, approach. In this theoretical review, we outline some limitations of treating executive functions as stable traits and of treating bilinguals as a uniform group when compared to monolinguals. To build on what we have learned from group comparisons, we advocate for an emerging complementary approach to the question of cognition and bilingualism. Using an approach that compares bilinguals to themselves under different linguistic or cognitive contexts allows researchers to ask questions about how language and cognitive processes interact based on dynamically fluctuating cognitive and neural states. A States approach, which has already been used by bilingualism researchers, allows for cause-and-effect hypotheses and shifts our focus from questions of group differences to questions of how varied linguistic environments influence cognitive operations in the moment and how fluctuations in cognitive engagement impact language processing.

Composition within and between Languages in the Bilingual Mind: MEG Evidence from Korean/English Bilinguals

The ability of the human brain to build complex expressions from simpler parts is fascinating, but the ability of the bilingual brain to do so is perhaps even more remarkable. When highly proficient bilinguals converse, they can fluidly switch from one language to another even inside sentences. Thus, they build expressions using words from more than one language. How are bilinguals able to compose words across different languages in real time? While robust evidence has implicated the left anterior temporal lobe (LATL) for the composition of words within one language, we do not know how the LATL, or other regions implicated for composition, operates when the language switches. We also do not know whether prefrontal regions associated with language control are recruited for language switching during composition. We addressed these questions with magnetoencephalography measurements in bilinguals who are fluent in two typologically distant languages, English and Korean. We observed early composition effects in the LATL at ∼200 ms that were unaffected by either language or orthography switching, which was also varied (Hangul vs Roman alphabet). Thus, the combinatory mechanism at 200 ms housed in the anterior temporal cortex appears blind to the language in which its input concepts are expressed. However, in later time windows, language and orthography switching interacted both in regions implicated for composition [LATL, ventromedial prefrontal cortex, left inferior frontal gyrus (LIFG)] as well as in regions associated with language control (ACC, LIFG). This establishes a starting point for understanding how bilingual brains code switch: words are initially combined without consideration of which language they come from, but language switching affects later processing.

Bilingualism contributes to reserve and working memory efficiency: Evidence from structural and functional neuroimaging

This study compared brain and behavioral outcomes for monolingual and bilingual older adults who reported no cognitive or memory problems on three types of memory that typically decline in older age, namely, working memory (measured by n-back), item, and associative recognition. The results showed that bilinguals were faster on the two-back working memory task than monolinguals but used a set of frontostriatal regions less than monolinguals. There was no group difference on an item/associative recognition task. In brain structure, gray matter volume and white matter integrity (fractional anisotropy) were generally lower in bilinguals than in monolinguals, but bilinguals had better white matter integrity than monolinguals in the bilateral superior corona radiata and better gray matter density in the left inferior temporal gyrus. These regions may help preserve bilinguals' executive functions despite generally more significant atrophy throughout the brain than monolinguals in that these structures contribute to efficient communication between executive frontal regions and subcortical motor regions, and perceptual pathways. Reliable negative correlations between brain structure and age were only observed in bilinguals, and to the extent that bilinguals (but not monolinguals) had better brain structure, their performance was enhanced. Collectively, the findings provide evidence for reserve in bilingual older adults.

The Quest for Signals in Noise: Leveraging Experiential Variation to Identify Bilingual Phenotypes

Increasing evidence suggests that bilingualism does not, in itself, result in a particular pattern of response, revealing instead a complex and multidimensional construct that is shaped by evolutionary and ecological sources of variability. Despite growing recognition of the need for a richer characterization of bilingual speakers and of the different contexts of language use, we understand relatively little about the boundary conditions of putative “bilingualism” effects. Here, we review recent findings that demonstrate how variability in the language experiences of bilingual speakers, and also in the ability of bilingual speakers to adapt to the distinct demands of different interactional contexts, impact interactions between language use, language processing, and cognitive control processes generally. Given these findings, our position is that systematic variation in bilingual language experience gives rise to a variety of phenotypes that have different patterns of associations across language processing and cognitive outcomes. The goal of this paper is thus to illustrate how focusing on systematic variation through the identification of bilingual phenotypes can provide crucial insights into a variety of performance patterns, in a manner that has implications for previous and future research.

Modeling Bilingual Lexical Processing Through Code-Switching Speech: A Network Science Approach

The study of code-switching (CS) speech has produced a wealth of knowledge in the understanding of bilingual language processing and representation. Here, we approach this issue by using a novel network science approach to map bilingual spontaneous CS speech. In Study 1, we constructed semantic networks on CS speech corpora and conducted community detections to depict the semantic organizations of the bilingual lexicon. The results suggest that the semantic organizations of the two lexicons in CS speech are largely distinct, with a small portion of overlap such that the semantic network community dominated by each language still contains words from the other language. In Study 2, we explored the effect of clustering coefficients on language choice during CS speech, by comparing clustering coefficients of words that were code-switched with their translation equivalents (TEs) in the other language. The results indicate that words where the language is switched have lower clustering coefficients than their TEs in the other language. Taken together, we show that network science is a valuable tool for understanding the overall map of bilingual lexicons as well as the detailed interconnections and organizations between the two languages.

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.

Single-cell atlas of domestic pig cerebral cortex and hypothalamus

The brain of the domestic pig (Sus scrofa domesticus) has drawn considerable attention due to its high similarities to that of humans. However, the cellular compositions of the pig brain (PB) remain elusive. Here we investigated the single-nucleus transcriptomic profiles of five regions of the PB (frontal lobe, parietal lobe, temporal lobe, occipital lobe, and hypothalamus) and identified 21 cell subpopulations. The cross-species comparison of mouse and pig hypothalamus revealed the shared and specific gene expression patterns at the single-cell resolution. Furthermore, we identified cell types and molecular pathways closely associated with neurological disorders, bridging the gap between gene mutations and pathogenesis. We reported, to our knowledge, the first single-cell atlas of domestic pig cerebral cortex and hypothalamus combined with a comprehensive analysis across species, providing extensive resources for future research regarding neural science, evolutionary developmental biology, and regenerative medicine.

Incremental Language Comprehension Difficulty Predicts Activity in the Language Network but Not the Multiple Demand Network

What role do domain-general executive functions play in human language comprehension? To address this question, we examine the relationship between behavioral measures of comprehension and neural activity in the domain-general "multiple demand" (MD) network, which has been linked to constructs like attention, working memory, inhibitory control, and selection, and implicated in diverse goal-directed behaviors. Specifically, functional magnetic resonance imaging data collected during naturalistic story listening are compared with theory-neutral measures of online comprehension difficulty and incremental processing load (reading times and eye-fixation durations). Critically, to ensure that variance in these measures is driven by features of the linguistic stimulus rather than reflecting participant- or trial-level variability, the neuroimaging and behavioral datasets were collected in nonoverlapping samples. We find no behavioral-neural link in functionally localized MD regions; instead, this link is found in the domain-specific, fronto-temporal "core language network," in both left-hemispheric areas and their right hemispheric homotopic areas. These results argue against strong involvement of domain-general executive circuits in language comprehension.

Incremental Language Comprehension Difficulty Predicts Activity in the Language Network but Not the Multiple Demand Network

What role do domain-general executive functions play in human language comprehension? To address this question, we examine the relationship between behavioral measures of comprehension and neural activity in the domain-general "multiple demand" (MD) network, which has been linked to constructs like attention, working memory, inhibitory control, and selection, and implicated in diverse goal-directed behaviors. Specifically, functional magnetic resonance imaging data collected during naturalistic story listening are compared with theory-neutral measures of online comprehension difficulty and incremental processing load (reading times and eye-fixation durations). Critically, to ensure that variance in these measures is driven by features of the linguistic stimulus rather than reflecting participant- or trial-level variability, the neuroimaging and behavioral datasets were collected in nonoverlapping samples. We find no behavioral-neural link in functionally localized MD regions; instead, this link is found in the domain-specific, fronto-temporal "core language network," in both left-hemispheric areas and their right hemispheric homotopic areas. These results argue against strong involvement of domain-general executive circuits in language comprehension.

Unexpected words or unexpected languages? Two ERP effects of code-switching in naturalistic discourse

Bilingual speakers often switch between languages in conversation without any advance notice. Psycholinguistic research has found that these language shifts (or code-switches) can be costly for comprehenders in certain situations. The present study explores the nature of these costs by comparing code-switches to other types of unexpected linguistic material. To do this, we used a novel EEG paradigm, the Storytime task, in which we record readings of natural texts, and then experimentally manipulate their properties by splicing in words. In this study, we manipulated the language of our target words (English, Spanish) and their fit with the preceding context (strong-fit, weak-fit). If code-switching incurs a unique cost beyond that incurred by an unexpected word, then we should see an additive pattern in our ERP indices. If an effect is driven by lexical expectation alone, then there should be a non-additive interaction such that all unexpected forms incur a similar cost. We found three effects: a general prediction effect (a non-additive N400), a post-lexical recognition of the switch in languages (an LPC for code-switched words), and a prolonged integration difficulty associated with weak-fitting words regardless of language (a sustained negativity). We interpret these findings as suggesting that the processing difficulties experienced by bilinguals can largely be understood within more general frameworks for understanding language comprehension. Our findings are consistent with the broader literature demonstrating that bilinguals do not have two wholly separate language systems but rather a single language system capable of using two coding systems.

Rapid attentional adaptations due to language (monolingual vs bilingual) context

Does our general attentional system adapt to the language context we are in? Bilinguals switch between contexts in which only one language is present or both languages are equiprobable. Previous research by Wu and Thierry (2013) suggested that the bilingual language context can modify the workings of inhibitory control mechanisms. Here we investigate whether this can be replicated and whether other attentional mechanisms (alerting and orienting) also adjust depending on whether we are in a bilingual or a monolingual situation. Bilinguals performed the Attentional Network Task (ANT) task, which allows us to measure three types of attentional processes: alerting, orienting and executive control. Crucially, while performing the ANT task, participants also saw words presented in only one language (e.g., Catalan; monolingual context) or in two languages (Catalan and Spanish; bilingual context); this allowed us to assess whether the three attentional processes would be modified by language context. Compared to the monolingual context, in the bilingual context the target-P3 amplitude was enhanced for the alerting and executive control networks but not for the orienting network. This suggests that bilinguals' state of alertness was enhanced when surrounded by words from two languages. Exploratory analyses reveal that within the bilingual context, language switches have an alerting effect, as indexed by a greater target-N1, thus impacting upcoming visual processing of the flanker. Response hand activation is speeded up for congruent trials in a similar way that arbitrary alerting cues speed them up. This speed-up was reflected in a greater LRP in the bilingual context, but it was not reflected in behavioral measures (RTs or ACC). Thus, a bilingual context can enhance attentional capacity towards non-linguistic information. It also reveals how flexible the cognitive system is.

Lexical-semantic processing costs are not inherent to intra-sentential code-switching: The role of switching habits

A bank of past electrophysiological research suggests that code-switching (i.e., the use of multiple languages during a single conversational event) is characterized by increased processing costs. However, the majority of these studies tested bilinguals who did not necessarily code-switch on a regular basis. In order to investigate the impact of switching habits on language processing, two groups of French-English bilinguals (habitual code-switchers and non-habitual code-switchers) read sentences containing unilingual and switched determiner phrases while their EEG was recorded. The findings indicate important processing differences between the groups. Notably, switched trials (particularly those with a French determiner) generated an increased negativity from 300 to 500 ms for non-habitual code-switchers, but not for habitual code-switchers. The veritable impact of switching habits were also supported by a correlation analysis. This finding suggests that code-switching is not inherently effortful to process, but rather, that comprehension costs are related to idiosyncratic factors, such as the extent of prior exposure to code-switched input. An LPC was also observed from 500 to 900 for habitual code-switchers; for non-habitual switchers, this effect may have been attenuated by the long-lasting N400 effect. We advance several possible interpretations for the late positivity. Altogether, the results from the current study support the claim that the code-switching cost observed in previous literature may be linked to the bilingual samples tested in those studies: habitual code-switchers may not find switches effortful to process, but not all bilinguals code-switch. We highlight the importance of experience and individual differences in the study of bilingual cognition.

Should I focus on self-language actions or should I follow others? Cross-language interference effects in voluntary and cued language switching

We examined whether and how language produced by others influences self-language processes. This study addressed this issue by looking at effects of comprehension on language switching in cued and voluntary switching contexts. During voluntary language switching, Chinese-English bilinguals were more likely to repeat the language they previously used themselves than to repeat the language produced by others. Furthermore, during both voluntary and cued language switching, bilinguals showed larger switch costs when switching between languages themselves than when switching after hearing another language. This suggests that cross-language interference may primarily stem from the self-language system rather than from language produced by others.

Language switching training modulates the neural network of non-linguistic cognitive control

Bilingual language experience, such as switching between languages, has been shown to shape both cognitive and neural mechanisms of non-linguistic cognitive control. However, the neural adaptations induced by language switching remain unclear. Using fMRI, the current study examined the impact of short-term language switching training on the neural network of domain-general cognitive control for unbalanced Chinese-English bilinguals. Effective connectivity maps were constructed by using the extended unified structural equation models (euSEM) within 10 common brain regions involved in both language control and domain-general cognitive control. Results showed that, the dorsal anterior cingulate cortex/pre-supplementary motor area (dACC/pre-SMA) lost connection from the right thalamus after training, suggesting that less neural connectivity was required to complete the same domain-general cognitive control task. These findings not only provide direct evidence for the modulation of language switching training on the neural interaction of domain-general cognitive control, but also have important implications for revealing the potential neurocognitive adaptation effects of specific bilingual language experiences.

Processing of Code-Switched Sentences in Noise by Bilingual Children

Purpose The purpose of the current study was to examine the effects of code-switching on bilingual children's online processing and offline comprehension of sentences in the presence of noise. In addition, the study examined individual differences in language ability and cognitive control skills as moderators of children's ability to process code-switched sentences in noise. Method The participants were 50 Spanish-English bilingual children, ages 7;0-11;8 (years;months). Children completed an auditory moving window task to examine whether they processed sentences with code-switching more slowly and less accurately than single-language sentences in the presence of noise. They completed the Dimensional Change Card Sort task to index cognitive control and standardized language measures in English and Spanish to index relative language dominance and overall language ability. Results Children were significantly less accurate in answering offline comprehension questions about code-switched sentences presented in noise compared to single-language sentences, especially for their dominant language. They also tended to exhibit slower processing speed, but costs did not reach significance. Language ability had an overall effect on offline comprehension but did not moderate the effects of code-switching. Cognitive control moderated the extent to which offline comprehension costs were affected by language dominance. Conclusions The findings of the current study suggest that code-switching, especially in the presence of background noise, may place additional demands on children's ability to comprehend sentences. However, it may be the processing of the nondominant language, rather than code-switching per se, that is especially difficult in the presence of noise.

Is codeswitching easy or difficult? Testing processing cost through the prosodic structure of bilingual speech

A common practice often attested in bilingual and multilingual communities the world over is the combination of languages within a single utterance or conversation, a practice known as codeswitching. While sociolinguistic studies of spontaneous codeswitching have demonstrated its structure and systematicity, psycholinguistic approaches have focused on the cognitive mechanisms underlying language switching, most often at the lexical level. In the present study, we seek to investigate these mechanisms using spontaneous codeswitching from an established community of Spanish-English bilinguals in northern New Mexico. Focusing on the clausal rather than the lexical level, we find that global speech rates are fastest when bilinguals codeswitch compared to speaking only one language at a time. These results point to codeswitching as a unique discourse mode that these bilinguals use to facilitate production and suggests that what may appear costly at one level may be beneficial at another.

Bilingualism and domain-general cognitive functions from a neural perspective: A systematic review

A large body of research has indicated that bilingualism - through continual practice in language control - may impact cognitive functions, as well as relevant aspects of brain function and structure. The present review aimed to bring together findings on the relationship between bilingualism and domain-general cognitive functions from a neural perspective. The final sample included 210 studies, covering findings regarding neural responses to bilingual language control and/or domain-general cognitive tasks, as well as findings regarding effects of bilingualism on non-task-related brain function and brain structure. The evidence indicates that a) bilingual language control likely entails neural mechanisms responsible for domain-general cognitive functions; b) bilingual experiences impact neural responses to domain-general cognitive functions; and c) bilingual experiences impact non-task-related brain function (both resting-state and metabolic function) as well as aspects of brain structure (both macrostructure and microstructure), each of which may in turn impact mental processes, including domain-general cognitive functions. Such functional and structural neuroplasticity associated with bilingualism may contribute to both cognitive and neural reserves, producing benefits across the lifespan.

Neural signatures of inhibitory control in intra-sentential code-switching: Evidence from fMRI

In this study we examined the neural control mechanisms that are at play when habitual code-switchers read code-switches embedded in a sentence context. The goal was also to understand if and to what extent the putative control network that is engaged during the comprehension of code-switched sentences is modulated by the linguistic regularity of those switches. Towards that goal, we tested two different types of code switches (switches at the noun-phrase boundary and switches at the verb-phrase boundary) that despite being both represented in naturalistic corpora of code switching, show different distributional properties. Results show that areas involved in general cognitive control (e.g., pre-SMA, anterior cingulate cortex) are recruited when processing code-switched sentences, relative to non-code-switched sentences. Additionally, significant activation in the cerebellum when processing sentences containing code-switches at the noun-phrase boundary suggests that habitual code-switchers might engage a wider control network to adapt inhibitory control processes according to task demands. Results are discussed in the context of the current literature on neural models of bilingual language control.

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.

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.