How does bilingualism modify cognitive function? Attention to the mechanism

Selective attention in cognitive processing revisited: A Long-term Re-evaluation

The volume by Harris (1992) was published at a time when research on the cognitive effects of bilingualism was in its infancy. In this article I revisit the chapter I contributed to that volume and evaluate the extent to which the arguments presented there remain valid. Specifically, I review three claims I made, namely, that the effects of bilingual experience extend into nonverbal domains, that these effects were continuous in nature and not categorical, and that selective attention was the key to explaining cognitive change in bilinguals. Thirty years later, these claims remain largely intact. In contrast, the claim that the mechanism for the effects comes from a specific aspect of linguistic processing that transfers to other domains must be rejected.

Is adaptation involved in bilingual language production? A fresh look at the assumptions motivating potential bilingual-monolingual differences in adaptive control

One of the hottest debates in psychology-whether bilingual-monolingual differences exist in cognitive control-is at a stalemate. Here we propose that the stalemate could be broken by shifting the research focus from whether those differences emerge to why they should. We offer an example of this approach by testing the assumption of current theories of language-control associations that adaptive control is involved in bilingualism, specifically language production. Unbalanced Italian-English bilinguals living in the Milan area completed a Stroop task in their L1 and a picture-naming task in their L2. Both tasks involved a manipulation of the proportion of the type of stimuli that are assumed to require control, i.e., incongruent stimuli in the Stroop task (e.g., the word RED written in blue) and pictures with noncognate names in the picture-naming task (e.g., the picture of a horse, whose Italian name, "cavallo," has a very different pronunciation). Both confirmatory and exploratory analyses showed a clear dissociation between the two tasks, with the Stroop task producing an interactive pattern indicative of adaptive-control involvement and the picture-naming task failing to produce a similar one. These results suggest that adaptive control may not be involved in bilingual language production and, therefore, may not produce bilingual-monolingual differences in cognitive control. It is hoped that this research will inspire a change in the study of language-control associations, pushing future research efforts towards grounding the assumptions for those associations in empirical evidence.

Attention networks in multilingual adults who do and who do not stutter

This study investigated whether multilinguals who stutter differ from multilinguals who do not stutter in terms of attention networks. Towards that end, it measured (a) performance differences in attention networks between multilinguals who stutter and those who do not stutter and (b) the correlation between stuttering characteristics and attention networks. Twenty-four multilingual Dutch-English speaking adults (20-46y), half of whom were diagnosed with stuttering, completed the Attentional Network Task (ANT) that evaluates the attention networks of alerting, orienting, and executive control. A language and social background questionnaire and a lexical decision task (LexTALE) assessed the participants' language proficiency. The Stuttering Severity Instrument 4th Ed. and the Brief Version of the Unhelpful Thoughts and Beliefs About Stuttering Scale were used to evaluate stuttering characteristics. The two groups did not differ in the ANT in terms of reaction time and error rate scores. Furthermore, no differences were observed in the three attention networks between the groups. Lastly, no correlation was found between stuttering characteristics and attention networks. The results suggest that the attention abilities of multilinguals who stutter do not differ from multilinguals who do not stutter.

Bilingualism modifies cognition through adaptation, not transfer

The standard explanation for bilingual effects on cognition is that an aspect of language processing transfers to nonverbal cognitive performance, leading to improvements in executive functioning. However, much evidence is incompatible with that view, and transfer across those domains seems unlikely. The present argument is that bilingual experience modifies cognition through an adaptation to the underlying attention system, making attention more efficient. 'Transfer' focuses on the overlap of specific processes, so task similarity predicts outcomes. By contrast, 'adaptation' focuses on recruitment of the modified resource, so the degree of attention required predicts outcome. In this view, bilinguals require less attentional effort than monolinguals for similar levels of performance, and outperform monolinguals on tasks with high attention demands regardless of task similarity.

Listening comprehension in a home language: a case of Russian in Germany

Listening comprehension is central to language learning, yet it remains the least understood and least researched skill. This statement is still relevant today, as there is insufficient research to explore listening comprehension from the perspective of family-related multilingualism and to consider the complete linguistic repertoire of multilingual speakers. Moreover, with regard to home language, listening comprehension is assumed to be a more developed language competence than reading or writing. Based on the mentioned research, the aim of the present study is to investigate listening comprehension and its influencing factors specifically in German-Russian simultaneous bilinguals aged 13-19 (n = 99) by considering the home- and majority language. The study uses quantitative data collection methods such as linguistic tests in Russian and German for the elicitation in different levels of listening and questionnaires for strategy use and background. The research questions are as follows: What does the language proficiency and input in Russian look like? (1) Regarding listening comprehension in Russian as a home language, are there differences between the speakers within comprehension on different levels, e.g., is sound decoding easier than sentence parsing? (2) If there are differences in Russian as a home language, which linguistic and background variables can correlate with the performance of listening comprehension on its different levels? Concerning the first research question, the results show relevant differences between four different levels of listening comprehension (phoneme, word, sentence, and text level), which strengthened the assumed complexity of listening comprehension in the home language. In addition, the results show different connections between the listening comprehension competence and the input from different family members, as well as exposure to film and television in the home and majority language.

Heterogeneity in cognitive profiles of monolingual and bilingual Hispanic/Latino older adults in HABS-HD

OBJECTIVE

The present study characterized heterogeneity in the cognitive profiles of monolingual and bilingual Latino older adults enrolled in the HABS-HD.

METHODS

A total of 859 cognitively unimpaired older adults completed neuropsychological testing. Raw scores for cognitive tests were converted to z-scores adjusted for age, education, sex, and language of testing. A latent profile analysis (LPA) was conducted for monolingual and bilingual speaker groups. A series of 2-5 class solutions were examined, and the optimal model was selected based on fit indices, posterior probabilities, proportion of sample sizes, and pattern of scores. Identified classes were compared on sociodemographic, psychosocial, and health characteristics.

RESULTS

For the monolingual group (n = 365), a 3-class solution was optimal; this consisted of a Low Average Memory group with low average verbal memory performances on the SEVLT Total Learning and Delayed Recall trials, as well as an Average Cognition group and a High Average Cognition group. For the bilingual group (n = 494), a 3-class solution was observed to be optimal; this consisted of a Low Average Memory group, with low average verbal memory performances on the learning and delayed recall trials of Logical Memory; a Low Average Executive group, where performance on Trails A and B and Digit Substitution were the lowest; and a High Average Cognition group, where performance was generally in the high average range across most cognitive measures.

CONCLUSIONS

Cognitive class solutions differed across monolingual and bilingual groups and illustrate the need to better understand cognitive variability in linguistically diverse samples of Latino older adults.

Brain correlates of attentional load processing reflect degree of bilingual engagement: Evidence from EEG

The present study uses electroencephalography (EEG) with an N-back task (0-, 1-, and 2-back) to investigate if and how individual bilingual experiences modulate brain activity and cognitive processes. The N-back is an especially appropriate task given recent proposals situating bilingual effects on neurocognition within the broader attentional control system (Bialystok and Craik, 2022). Beyond its working memory component, the N-Back task builds in complexity incrementally, progressively taxing the attentional system. EEG, behavioral and language/social background data were collected from 60 bilinguals. Two cognitive loads were calculated: low (1-back minus 0-back) and high (2-back minus 0-back). Behavioral performance and brain recruitment were modeled as a function of individual differences in bilingual engagement. We predicted task performance as modulated by bilingual engagement would reflect cognitive demands of increased complexity: slower reaction times and lower accuracy, and increase in theta, decrease in alpha and modulated N2/P3 amplitudes. The data show no modulation of the expected behavioral effects by degree of bilingual engagement. However, individual differences analyses reveal significant correlations between non-societal language use in Social contexts and alpha in the low cognitive load condition and age of acquisition of the L2/2L1 with theta in the high cognitive load. These findings lend some initial support to Bialystok and Craik (2022), showing how certain adaptations at the brain level take place in order to deal with the cognitive demands associated with variations in bilingual language experience and increases in attentional load. Furthermore, the present data highlight how these effects can play out differentially depending on cognitive testing/modalities - that is, effects were found at the TFR level but not behaviorally or in the ERPs, showing how the choice of analysis can be deterministic when investigating bilingual effects.

Comparison of executive functions in Russian and Japanese preschoolers

This study analyzed differences in level of main executive function (EF) components (such as inhibition, working memory, and cognitive flexibility) among Russian and Japanese preschoolers. The study involved 102 children of 5-6.9 years old: 51 child from Russia and 51 child from Japan. Out of 102 children 48 were boys and 54 girls. It was found that the cognitive flexibility level in Russian children is higher and inhibition level is lower than in Japanese children. The results of the boys' EF comparison showed that boys from Russia have lower cognitive and physical inhibition levels than boys from Japan. Also it was shown that cognitive flexibility in Russian girls is significantly higher and cognitive inhibition is lower than in Japanese girls. The results obtained are discussed from the point of view of possible cultural differences in the two countries studied, which are manifested in the expectations of adults from children.

The effects of language learning on cognitive functioning and psychosocial well-being in cognitively healthy older adults: A semi-blind randomized controlled trial

This study investigated the impact of language learning in comparison to other complex learning activities on cognitive functioning and psychosocial well-being in cognitively healthy, community-dwelling older adults. In a randomized controlled trial, 43 Dutch functionally monolinguals aged 65-78 completed a three-month English course (n = 15), music training (n = 13), or a lecture series (n = 15). Cognitive functioning (global cognition, cognitive flexibility, episodic memory, working memory, verbal fluency, and attention) and psychosocial well-being were assessed before and immediately after the intervention, and at a four-month follow-up. The language learners significantly improved on episodic memory and cognitive flexibility. However, the magnitude of cognitive change did not significantly differ between the language learning and music training conditions, except for a larger positive change in cognitive flexibility for the language learners from pretest to follow-up. Our results suggest that language learning in later life can improve some cognitive functions and fluency in the additional language, but that its unique effects seem limited.

Second language learning in older adults modulates Stroop task performance and brain activation

Introduction

Numerous studies have highlighted cognitive benefits in lifelong bilinguals during aging, manifesting as superior performance on cognitive tasks compared to monolingual counterparts. Yet, the cognitive impacts of acquiring a new language in older adulthood remain unexplored. In this study, we assessed both behavioral and fMRI responses during a Stroop task in older adults, pre- and post language-learning intervention.

Methods

A group of 41 participants (age:60-80) from a predominantly monolingual environment underwent a four-month online language course, selecting a new language of their preference. This intervention mandated engagement for 90 minutes a day, five days a week. Daily tracking was employed to monitor progress and retention. All participants completed a color-word Stroop task inside the scanner before and after the language instruction period.

Results

We found that performance on the Stroop task, as evidenced by accuracy and reaction time, improved following the language learning intervention. With the neuroimaging data, we observed significant differences in activity between congruent and incongruent trials in key regions in the prefrontal and parietal cortex. These results are consistent with previous reports using the Stroop paradigm. We also found that the amount of time participants spent with the language learning program was related to differential activity in these brain areas. Specifically, we found that people who spent more time with the language learning program showed a greater increase in differential activity between congruent and incongruent trials after the intervention relative to before.

Discussion

Future research is needed to determine the optimal parameters for language learning as an effective cognitive intervention for aging populations. We propose that with sufficient engagement, language learning can enhance specific domains of cognition such as the executive functions. These results extend the understanding of cognitive reserve and its augmentation through targeted interventions, setting a foundation for future investigations.

Comparing pragmatic abilities across multiple languages in adults with ADHD: Insights from a self-report questionnaire

Attention-Deficit/Hyperactivity Disorder (ADHD) is associated with pragmatic language impairments in children, but less is known about the communicative abilities of adults with ADHD, especially when using a second or third language. In this study, we developed a questionnaire to collect self-report measures of a set of pragmatic skills in a person's first, second and third language, comparing adults with and without an ADHD diagnosis. One hundred seventy-nine multilingual adults with (N = 91) and without ADHD (N = 88) completed the survey. As predicted, adults with ADHD reported more pragmatic difficulties than the control group. More specifically, people with ADHD showed pronounced impairments in regulating their behaviour in spoken interactions in the form of excessive talking, frequently interrupting others, and speaking without thinking first. Notably, these types of hyperactive and impulsive behaviours were significantly reduced when people with ADHD communicated in a second or third language. For pragmatic difficulties related to inattention such as concentrating on a conversation, both groups tended to be more inattentive in their third language compared to their first and second language. The understanding of non-literal language was only affected by ADHD in the first language and was generally more taxing in a language with lower proficiency levels. Our study contributes to a more nuanced understanding of how ADHD affects different kinds of communicative abilities in multilingual adults. It also has implications for clinical practice, highlighting the importance of assessing symptoms of inattention, hyperactivity, and impulsivity in a person's dominant language.

New insights into bilingual visual word recognition: State of the art on the role of orthographic markedness, its theoretical implications, and future research directions

In the past decade, research on bilingual visual word recognition has given rise to a new line of study focusing on a sublexical orthographic variable referred to as orthographic markedness, derived from the comparison of the two orthotactic distributions known by a bilingual reader. Orthographic markers have been shown to speed up language decisions but also, to some extent, to modulate language nonselectivity during lexical access (i.e., the degree of co-activation of lexical representations of the two languages). In this review, we (1) describe the results available in the literature about orthographic markedness on language membership detection and lexical access and discuss the locus of these effects, which leads us to (2) present theoretical extensions to the bilingual interactive activation models and discuss their respective adequacy to the data, finally leading us to (3) propose future research directions in the study of orthographic markedness, such as extension to different reading tasks and contexts as well as considering developmental and learning dynamics.

Assessing the Impact of Bilingualism on the Linguistic Skills of Children with Autism Spectrum Disorder (ASD) in Greece: A Scoping Review

(1) Background and Objectives: This review aims to identify the latest literature on the possible effect of bilingualism on the linguistic skills of children with autism spectrum disorder (ASD) residing in Greece. (2) Materials and Methods: The literature was searched in the databases of Scopus and PubMed by selecting articles and by reviewing four studies published in peer-reviewed journals. This Scoping Review is based on the standards of PRISMA recommendations for scoping reviews, while the PCC framework was used as a guide to construct clear and meaningful objectives and eligibility criteria. (3) Results: The publications included in the review addressed a variety of language-related skills, including morphology, the syntax-pragmatics interface, narrative ability, as well as both receptive and expressive language skills. (4) Conclusions: Three out of four studies provide evidence that bilingual ASD children are not disadvantaged compared to monolingual peers but rather enjoy some benefits, to a certain extent, due to bilingualism. However, the number of the reviewed studies as well as the limitations of the studies themselves render this conclusion tentative. Additionally, the findings set guidelines that speech therapists, educators, psychologists, and doctors in the Greek context need to follow when treating or educating bilingual children with ASD.

How Mandarin-English bilinguals interpret qián/forward: impact of language proficiencies on retrieval of temporal concepts

Mandarin qián and English forward are semantically equivalent in the domain of Space, but could be semantically opposite in the domain of Time. In other words, equivalent spatial lexical items could convey opposite temporal concepts. What temporal concepts conveyed by qián and forward would be retrieved by Mandarin-English (M-E) bilinguals with different language proficiencies? Drawing a sample from college students in Mainland China, this study examines how L1 and L2 proficiencies would affect M-E bilinguals' retrieval of temporal concepts by examining their interpretation of the Mandarin temporal metaphor of qián and the English temporal metaphors of forward. The results show that L1 temporal concepts would be retrieved more frequently than L2 temporal concepts regardless of the testing languages, that L1 and L2 proficiencies were not predictors for the way of interpretation, and that the higher L2 proficiency group could retrieve temporal concepts in line with the testing languages with higher accuracy than the lower L2 proficiency group. The findings suggest that bilinguals with higher L2 proficiency may be able to represent temporal concepts with language tags or may have an attentional and/or inhibitory control advantage.

Is there a bilingual advantage in auditory attention among children? A systematic review and meta-analysis of standardized auditory attention tests

A wealth of research has investigated the associations between bilingualism and cognition, especially in regards to executive function. Some developmental studies reveal different cognitive profiles between monolinguals and bilinguals in visual or audio-visual attention tasks, which might stem from their attention allocation differences. Yet, whether such distinction exists in the auditory domain alone is unknown. In this study, we compared differences in auditory attention, measured by standardized tests, between monolingual and bilingual children. A comprehensive literature search was conducted in three electronic databases: OVID Medline, OVID PsycInfo, and EBSCO CINAHL. Twenty studies using standardized tests to assess auditory attention in monolingual and bilingual participants aged less than 18 years were identified. We assessed the quality of these studies using a scoring tool for evaluating primary research. For statistical analysis, we pooled the effect size in a random-effects meta-analytic model, where between-study heterogeneity was quantified using the I2 statistic. No substantial publication bias was observed based on the funnel plot. Further, meta-regression modelling suggests that test measure (accuracy vs. response times) significantly affected the studies' effect sizes whereas other factors (e.g., participant age, stimulus type) did not. Specifically, studies reporting accuracy observed marginally greater accuracy in bilinguals (g = 0.10), whereas those reporting response times indicated faster latency in monolinguals (g = -0.34). There was little difference between monolingual and bilingual children's performance on standardized auditory attention tests. We also found that studies tend to include a wide variety of bilingual children but report limited language background information of the participants. This, unfortunately, limits the potential theoretical contributions of the reviewed studies. Recommendations to improve the quality of future research are discussed.

Individual variation in bilingual vocabulary in preschoolers with developmental language disorder

BACKGROUND

It is unclear how speech production, selective attention, and phonological working memory are related to first- (L1) and second-language (L2) vocabularies in bilingual preschoolers with Developmental Language Disorder (DLD).

AIMS

To study individual variation in vocabularies in DLD bilingual preschoolers by (1) comparing them to typically developing (TD) bilingual, and TD and DLD monolingual peers; (2) differentially predicting L2 vocabulary; and (3) identifying and characterizing bilinguals' L1/L2 vocabulary profiles.

METHODS

We measured the selective attention, working memory, and L1 Turkish/Polish (where applicable) and L1/L2 Dutch speech and vocabulary abilities of 31 DLD bilingual, 37 TD bilingual, and 61 DLD and 54 TD Dutch monolingual three-to-five year-olds.

RESULTS

DLD bilinguals scored lower than TD bilinguals and TD/DLD monolinguals on all measures, except L2 vocabulary, where all bilinguals underperformed all monolinguals. Selective attention predicted Dutch vocabulary across groups. Three bilingual vocabulary profiles emerged: DLD bilinguals were less likely to be L1 dominant, TD/DLD bilinguals with better attention more often had a Balanced high L1/L2 profile, while those with poorer selective attention and L1 speech tended to be L2 dominant.

CONCLUSIONS

These findings highlight the roles of L1 speech and selective attention, rather than L2 speech and working memory, in understanding bilingual vocabulary variation among DLD preschoolers.

Language prediction in monolingual and bilingual speakers: an EEG study

Prediction of upcoming words is thought to be crucial for language comprehension. Here, we are asking whether bilingualism entails changes to the electrophysiological substrates of prediction. Prior findings leave it open whether monolingual and bilingual speakers predict upcoming words to the same extent and in the same manner. We address this issue with a naturalistic approach, employing an information-theoretic metric, surprisal, to predict and contrast the N400 brain potential in monolingual and bilingual speakers. We recruited 18 Iranian Azeri-Persian bilingual speakers and 22 Persian monolingual speakers. Subjects listened to a story in Persian while their electroencephalogram (EEG) was recorded. Bayesian item-level analysis was used. While in monolingual speakers N400 was sensitive to information-theoretic properties of both the current and previous words, in bilingual speakers N400 reflected the properties of the previous word only. Our findings show evidence for a processing delay in bilingual speakers which is consistent with prior research.

Dual-Language Use and Cognitive Function Among Mexican Americans Aged 65 and Older

Background

Better English proficiency and higher frequency of using English among non-native speakers are associated with lower dementia risk.

Objective

We investigated if Mexican American older adults who use English and Spanish to a more similar degree demonstrate better cognitive function than those who use one language more than the other.

Methods

We used data from waves one (1992/93) to eight (2012/13) of the Hispanic Established Population for the Epidemiological Study of the Elderly. At baseline, participants were asked what language they usually use across communicative contexts. We based dual language on participants' use of Spanish and English within and across contexts. We categorized participants as low (n = 1,145), medium (n = 717), and high (n = 702) dual-language users. Linear mixed models were used to estimate the association between dual-language use, baseline Mini-Mental State Examination (MMSE) scores, and change in MMSE.

Results

Participants in the medium and high dual-language use categories scored 1.91 points and 3.03 points higher at wave one compared to the low dual-language use category. Adjusting for education reduced the association between dual-language use and baseline MMSE (medium B = 0.99 SE = 0.19 p < 0.01; high B = 1.41 SE = 0.21 p < 0.01). The association between dual-language use and decline in the MMSE was not statistically significant.

Conclusions

Greater dual-language use was associated with higher MMSE scores but not change in MMSE scores among Mexican Americans aged 65 and older. Future work should characterize bilingualism with greater nuance and use more rigorous cognitive measures to identify the components of the bilingual experience that may benefit the cognitive functioning of older adult bilinguals.

Multilingual Language Diversity Protects Native Language Production under Different Control Demands

The use of multiple languages has been found to influence individuals' cognitive abilities. Although some studies have also investigated the effect of multilingualism on non-native language proficiency, fewer studies have focused on how multilingual experience affects native language production. This study investigated the effect of multilingualism on native language production, specifically examining control demands through a semantic Go/No-Go picture naming task. The multilingual experience was quantified using language entropy, which measures the uncertainty and diversity of language use. Control demands were achieved by manipulating the proportion of Go (i.e., naming) trials in different conditions. Results showed that as control demands increased, multilingual individuals exhibited poorer behavioral performance and greater brain activation throughout the brain. Moreover, more diverse language use was associated with higher accuracy in naming and more interconnected brain networks with greater involvement of domain-general neural resources and less domain-specific neural resources. Notably, the varied and balanced use of multiple languages enabled multilingual individuals to respond more efficiently to increased task demands during native language production.

A neural mechanism of cognitive reserve: The case of bilingualism

Cognitive Reserve (CR) refers to the preservation of cognitive function in the face of age- or disease-related neuroanatomical decline. While bilingualism has been shown to contribute to CR, the extent to which, and what particular aspect of, second language experience contributes to CR are debated, and the underlying neural mechanism(s) unknown. Intrinsic functional connectivity reflects experience-dependent neuroplasticity that occurs across timescales ranging from minutes to decades, and may be a neural mechanism underlying CR. To test this hypothesis, we used voxel-based morphometry and resting-state functional connectivity analyses of MRI data to compare structural and functional brain integrity between monolingual and bilingual older adults, matched on cognitive performance, and across levels of second language proficiency measured as a continuous variable. Bilingualism, and degree of second language proficiency specifically, were associated with lower gray matter integrity in a hub of the default mode network - a region that is particularly vulnerable to decline in aging and dementia - but preserved intrinsic functional network organization. Bilingualism moderated the association between neuroanatomical differences and cognitive decline, such that lower gray matter integrity was associated with lower executive function in monolinguals, but not bilinguals. Intrinsic functional network integrity predicted executive function when controlling for group differences in gray matter integrity and language status. Our findings confirm that lifelong bilingualism is a CR factor, as bilingual older adults performed just as well as their monolingual peers on tasks of executive function, despite showing signs of more advanced neuroanatomical aging, and that this is a consequence of preserved intrinsic functional network organization.

Multilingualism is associated with small task-specific advantages in cognitive performance of older adults

The protective effects of multiple language knowledge on the maintenance of cognitive functions in older adults have been discussed controversially, among others, because of methodological inconsistencies between studies. In a sample of N = 528 German monolinguals and multilinguals (speaking two or more languages) older than 60 years, this study examined (1) whether speaking multiple languages is positively related to performance on tasks of interference suppression, working memory, concept shifting, and phonemic and semantic fluency, and (2) whether language proficiency and age of second language acquisition (AoA) are associated with cognitive performance of multilinguals. Controlling for education and daily activity, we found small cognitive benefits of speaking multiple languages on interference suppression, working memory, and phonemic fluency, but not on concept shifting and semantic fluency. Furthermore, no substantive correlations were found between language proficiency or AoA and cognitive performance. In conclusion, multilingualism appears to have small incremental effects on cognitive performance beyond education and daily activity in older age that are task-specific and widely independent of proficiency and AoA.

A Classification Bias and an Exclusion Bias Jointly Overinflated the Estimation of Publication Biases in Bilingualism Research

A publication bias has been argued to affect the fate of results in bilingualism research. It was repeatedly suggested that studies presenting evidence for bilingual advantages are more likely to be published compared to studies that do not report results in favor of the bilingual advantage hypothesis. This work goes back to the original claim and re-examines both the dataset and the classification of the studies that were employed. We find that the exclusion of published works such as doctoral dissertations, book chapters, and conference proceedings from the original dataset significantly inflated the presumed publication bias. Moreover, the estimation of the publication bias was affected by a classification bias that uses a mega-category that consists of both null and negative outcomes. Yet finding evidence for a bilingual disadvantage is not synonymous with obtaining a result indistinguishable from zero. Consequently, grouping together null and negative findings in a mega-category has various ramifications, not only for the estimation of the presumed publication bias but also for the field's ability to appreciate the insofar hidden correlations between bilingual advantages and disadvantages. Tracking biases that inflate scientific results is important, but it is not enough. The next step is recognizing the nested Matryoshka doll effect of bias-within-bias, and this entails raising awareness for one's own bias blind spots in science.

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.

Monolingual and bilingual children's performance on arithmetic fluency varies by language fluency

Research has demonstrated that learning two or more languages during development (i.e., becoming bilingual) shapes children's cognition in myriad ways. However, because such studies have largely been conducted using laboratory experiments, it is unclear how bilingualism may modulate more naturalistic cognitive skills such as arithmetic fluency. Moreover, how the relationship between speaking two (or more) languages and arithmetic varies with language fluency-specifically, the degree of bilingualism-has been understudied. Therefore, this study examined third- to fifth-grade monolingual (n = 70) and bilingual (n = 51) children's performance on an arithmetic fluency task. Monolinguals' and bilinguals' performance on the arithmetic fluency task did not differ. However, individual differences in the relation between children's arithmetic fluency and their language fluency were found, suggesting that bilingual children's skill in their nondominant language was associated with arithmetic fluency. These findings point to the importance of examining individual differences in language fluency among bilinguals to understand how bilingualism may shape cognitive skills.

Functional neural architecture of cognitive control mediates the relationship between individual differences in bilingual experience and behaviour

Bilinguals have often, but not always, been found to outperform monolinguals on domain-general attentional control. Inconsistent findings have been argued to stem, at least partly, from treating bilingualism as a uniform category and from not considering how neural adaptations to bilingual experiences modulate behavioural outcomes. The present study investigated how patterns of language experience, including language switching behaviour, duration and intensity/diversity of bilingual language use, influence the brain processes underlying cognitive control, and how these in turn translate to cognitive control performance. We examined reaction times and spectral dynamics of the electroencephalograms (EEG) of two-hundred-and-thirty-nine participants (about 70% bilinguals) with diverse language experiences during two cognitive control paradigms testing interference suppression (flanker and Simon task). Using structural equation modelling, we found that different bilingual experience factors were related with neurocognitive measures, which in turn were related with behavioural interference effects, for the flanker but not the Simon task. More specifically, increased frequency of language switching and intensity / diversity of bilingual language usage was negatively related to induced top-down control measures (especially midline-frontal theta), which in turn was beneficial for interference control. In contrast, duration of bilingual engagement correlated negatively with evoked bottom-up control measures (especially P3) and was therefore detrimental to interference control. We demonstrate here for the first time how the different factors of bilingual experience lead to different neural adaptations which impact behavioural outcomes. SIGNIFICANCE STATEMENT: Like other intensive experiences, bilingualism leads to brain adaptations. It results in structural changes in language areas, and, due to demands on language control, in brain areas associated with domain-general cognitive control. Related to this, bilinguals often outperform monolinguals on cognitive control tasks. But what is often ignored is that bilingualism is a multi-dimensional phenomenon, with variations such as diversity of language usage and duration of language use. The present large-scale study of neural functioning in bilingualism revealed for the first time how individual differences in bilingual experience lead to adaptations to brain functioning which in turn affect cognitive control behaviour. It exemplifies how the complexity of individual experiences plays a fundamental role in brain function.

Multivariate decoding methods reveal how speaking two dialects affects executive functions

How speaking two languages affects executive functions has been a long-standing debate and the mechanisms underlying the observed cognitive advantages of bilingualism remain unspecified. Here, using multivariate pattern classification methods, we decoded spatial patterns of neural signals associated with Flanker task performance in mono-dialectal and bi-dialectal speakers of Chinese. While univariate approach to even-related potentials (ERPs) showed no between-group difference, decoding accuracy of ERPs was reduced in bi-dialectal as compared to mono-dialectal speakers in both congruent-neutral and incongruent-neutral classifications. There was no effect of bidialectalism, however, on decoding accuracy of alpha-band oscillations, an electrophysiological index implicated in inhibition. Behavioural data analysed using the Drift Diffusion Model (DDM) showed facilitating effects of bidialectalism on non-decision times but no effect on drift rates. These findings demonstrate that using two dialects on a daily basis enhances general attentional deployment rather than affecting specific component of executive functions such as inhibitory control. Given that the two dialects of Chinese differed almost exclusively in phonology, the bidialectalism effect was most likely motivated by resolving phonological competition at lexical processing level.

Bilingualism modulates neural efficiency at rest through alpha reactivity

The aim of the present study was to investigate how resting state EEG rhythms reflect attentional processes and bilingual experience. We compared alpha and beta rhythms for monolingual and bilingual young adults in eyes open and eyes closed conditions using EEG measures of frequency power, reactivity, and coherence. Power shows the amount of brain activity at a given frequency band; reactivity indexes the desynchronization of neuronal activity when individuals open their eyes at rest; and coherence indicates the brain regions that have correlated activity. The results showed that bilinguals had similar alpha power as monolinguals in both resting conditions but less alpha reactivity across the whole scalp. There was also more focused activation for bilinguals expressed as more coherence in posterior electrodes, particularly when eyes were opened to direct attention. For beta, there were no group differences in power or reactivity, but there was higher coherence for monolinguals than bilinguals, a pattern consistent with previous literature showing that beta frequency was related to language learning and native language proficiency. These results are in line with a neural efficiency theory and suggest that bilinguals have a more efficient brain for attentional mechanisms than monolinguals at rest.

Executive functioning during verbal fluency tasks in bilinguals: A systematic review

BACKGROUND

Bilingualism is widespread and being bilingual is more common than being monolingual. The lifelong practice bilinguals receive from managing two languages seems to lead to a cognitive benefit. Conversely, bilingualism seems to affect language ability negatively due to less use of each known language.

AIMS

This systematic review aims to summarize the results of the studies on the effect of bilingualism on executive functioning assessed by verbal fluency tasks. The verbal fluency task is a neuropsychological measure of lexical retrieval efficiency and executive functioning.

METHODS

The review was conducted according to the PRISMA statement through searches in the scientific databases PsycINFO, PsycARTICLES, MEDLINE, PubMed, Web of Science and SCOPUS. Studies included in this review had at least one bilingual and monolingual group, participants over 18 years and one verbal fluency task. Studies that considered bimodal bilingual, second language learners, trilingual or multilingual people, and clinical populations were excluded. A total of 38 studies were included in the systematic review.

MAIN CONTRIBUTION

Quantitative analysis of performance did not show significant differences between monolinguals and bilinguals. Qualitative results are mixed, and no definitive conclusions can be drawn about a bilingual advantage or disadvantage in the verbal fluency tasks.

CONCLUSIONS

Normative data based on the monolingual population are not appropriate to test a bilingual population. It is necessary to take precautions in using this task, especially in clinical practice.

WHAT THIS PAPER ADDS

What is already known on the subject Bilingualism seems to lead to a cognitive benefit due to constantly monitoring the known languages to select the most suitable one for each interactional context and to affect language ability negatively due to less use of each known language but also to language ability negatively. What this paper adds to the existing knowledge This systematic review summarizes the results of the studies on the effect of bilingualism on executive functioning assessed by verbal fluency tasks, a neuropsychological measure of lexical retrieval efficiency and executive functioning. What are the potential or actual clinical implications of this work? Normative data based on the monolingual population are not appropriate to test a bilingual population. It is necessary to take precautions in using this task, especially in clinical practice.

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The Involvement of Listening Effort in Explaining Bilingual Listening Under Adverse Listening Conditions

The current review examines listening effort to uncover how it is implicated in bilingual performance under adverse listening conditions. Various measures of listening effort, including physiological, behavioral, and subjective measures, have been employed to examine listening effort in bilingual children and adults. Adverse listening conditions, stemming from environmental factors, as well as factors related to the speaker or listener, have been examined. The existing literature, although relatively limited to date, points to increased listening effort among bilinguals in their nondominant second language (L2) compared to their dominant first language (L1) and relative to monolinguals. Interestingly, increased effort is often observed even when speech intelligibility remains unaffected. These findings emphasize the importance of considering listening effort alongside speech intelligibility. Building upon the insights gained from the current review, we propose that various factors may modulate the observed effects. These include the particular measure selected to examine listening effort, the characteristics of the adverse condition, as well as factors related to the particular linguistic background of the bilingual speaker. Critically, further research is needed to better understand the impact of these factors on listening effort. The review outlines avenues for future research that would promote a comprehensive understanding of listening effort in bilingual individuals.

Can Speaking More Than One Language Help Prevent Alzheimer's Disease?

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Over-reliance on English hinders cognitive science

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An individualized functional magnetic resonance imaging protocol to assess semantic congruency effects on episodic memory in an aging multilingual population

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The Multifaceted Nature of Bilingualism and Attention

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Testing the Bilingual Cognitive Advantage in Toddlers Using the Early Executive Functions Questionnaire

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