Effects of Bilingual Language Use and Language Proficiency on 24-month-olds’ Cognitive Control

ABSTRACT

Although a bilingual advantage has been reported for various measures of cognitive control, most previous studies have looked at a limited range of cognitive control measures. Furthermore, they typically leave unaddressed whether positive effects of bilingualism hold for all bilinguals or whether these are modulated by differences in bilingual language use and proficiency of children and their parents. This study reports on tasks of selective attention and inhibitory control from 24-month-old bilinguals (n = 37) and monolinguals (n = 58). Their parents completed a Dutch vocabulary checklist assessing receptive and productive vocabulary as well as questionnaires on children’s attentional focusing, attention shifting and inhibitory control, and language background. Linear mixed-effect regressions showed no differences on cognitive control between the monolinguals and bilingual groups. However, analyses taking into account differences in children’s bilingual language use and proficiency and of their parents revealed a more nuanced picture. Specifically, children’s degree of balanced language usage predicted parent-rated cognitive control. Furthermore, bilingual toddlers who had parents were low proficient in one of the home languages showed significantly better performance on a selective attention task than toddlers whose parents were both proficient in both home languages. These findings suggest that both children’s active usage of two languages and their experience with switching depending on their interlocutor are related to cognitive control performance in young bilingual children. As such, they add to a growing body of evidence that the bilingual advantage in cognitive control is tied to specific conditions of bilingualism, already at a young age.     

Neurophysiological marker of inhibition distinguishes language groups on a non-linguistic executive function test

Successful interaction with the environment depends on flexible behaviors which require shifting attention, inhibiting primed responses, ignoring distracting information, and withholding motor responses. These abilities, termed executive function (EF), are believed to be mediated by inhibitory processes in the frontal lobes. Superior performance on EF tests (i.e., faster reaction times (RT), and fewer errors) has been shown in bilinguals compared to monolingual speakers. However, findings are inconsistent, and no study has directly linked this bilingual advantage to frontal lobe inhibitory processes. To clarify this uncertainty, we concomitantly tested neural inhibitory processes and behavioral responses on an EF test in bilinguals and monolinguals. Specifically, we compared English monolinguals (N = 15) to Spanish/English bilinguals (N = 13) on event-related brain potentials (ERP) during a non-linguistic, auditory Go/NoGo task, a task linked to non-motor, cognitive inhibition in monolinguals. Participants responded with a button press on trials in which target tone-pairs (Go trials) were presented and withheld their responses on non-target trials (NoGo trials). Results revealed significantly greater inhibition (i.e., greater mean N2 amplitude) in bilinguals compared to monolinguals during NoGo trials even though both groups performed the task equally well (i.e., withheld a motor response). On Go trials where participants pressed a response button, neither ERPs nor RT distinguished the groups. Additionally, scores on a second language proficiency test (i.e., English in our bilingual group) were positively correlated with N2 amplitude. These findings are the first to directly link this bilingual advantage to a neural correlate of inhibition and to reveal that inhibition in bilinguals is moderated by second language proficiency. Results are discussed in the context of plasticity, and we propose that evaluating bilinguals at varying levels of second-language proficiency may serve as a model of human neuroplasticity.     

On the time course of exogenous cueing effects in bilinguals: Higher proficiency in a second language is associated with more rapid endogenous disengagement

Previous investigations have demonstrated a bilingual advantage on various aspects of executive control. It remains unclear how the language proficiency of bilinguals might relate to the mechanisms involved in attentional disengagement. In the present investigation, we tested the hypothesis that high bilingual proficiency would lead to a more rapid endogenous disengagement of attention from task-irrelevant peripheral cues. We predicted that more rapid attentional disengagement would result in an earlier appearance of inhibition of return (IOR). In this study Hindi–English bilinguals who differed in their L2 (English) proficiency participated in a target detection task. Visual targets were preceded by uninformative peripheral cues at various stimulus onset asynchronies (SOAs) allowing for us to visualize the time course of cue-related facilitation and inhibition. High-proficient Hindi–English bilinguals showed an earlier appearance of IOR than did low-proficient bilinguals, suggesting increased efficiency in disengagement of attention from task-irrelevant inputs. Furthermore, consistent with the “global” advantage that characterizes bilinguals in many tasks, the high-proficient group outperformed low-proficient bilinguals in overall reaction time.     

Neurophysiological marker of inhibition distinguishes language groups on a non-linguistic executive function test

Successful interaction with the environment depends on flexible behaviors which require shifting attention, inhibiting primed responses, ignoring distracting information, and withholding motor responses. These abilities, termed executive function (EF), are believed to be mediated by inhibitory processes in the frontal lobes. Superior performance on EF tests (i.e., faster reaction times (RT), and fewer errors) has been shown in bilinguals compared to monolingual speakers. However, findings are inconsistent, and no study has directly linked this bilingual advantage to frontal lobe inhibitory processes. To clarify this uncertainty, we concomitantly tested neural inhibitory processes and behavioral responses on an EF test in bilinguals and monolinguals. Specifically, we compared English monolinguals (N = 15) to Spanish/English bilinguals (N = 13) on event-related brain potentials (ERP) during a non-linguistic, auditory Go/NoGo task, a task linked to non-motor, cognitive inhibition in monolinguals. Participants responded with a button press on trials in which target tone-pairs (Go trials) were presented and withheld their responses on non-target trials (NoGo trials). Results revealed significantly greater inhibition (i.e., greater mean N2 amplitude) in bilinguals compared to monolinguals during NoGo trials even though both groups performed the task equally well (i.e., withheld a motor response). On Go trials where participants pressed a response button, neither ERPs nor RT distinguished the groups. Additionally, scores on a second language proficiency test (i.e., English in our bilingual group) were positively correlated with N2 amplitude. These findings are the first to directly link this bilingual advantage to a neural correlate of inhibition and to reveal that inhibition in bilinguals is moderated by second language proficiency. Results are discussed in the context of plasticity, and we propose that evaluating bilinguals at varying levels of second-language proficiency may serve as a model of human neuroplasticity.     

On the time course of exogenous cueing effects in bilinguals: higher proficiency in a second language is associated with more rapid endogenous disengagement

Previous investigations have demonstrated a bilingual advantage on various aspects of executive control. It remains unclear how the language proficiency of bilinguals might relate to the mechanisms involved in attentional disengagement. In the present investigation, we tested the hypothesis that high bilingual proficiency would lead to a more rapid endogenous disengagement of attention from task-irrelevant peripheral cues. We predicted that more rapid attentional disengagement would result in an earlier appearance of inhibition of return (IOR). In this study Hindi-English bilinguals who differed in their L2 (English) proficiency participated in a target detection task. Visual targets were preceded by uninformative peripheral cues at various stimulus onset asynchronies (SOAs) allowing for us to visualize the time course of cue-related facilitation and inhibition. High-proficient Hindi-English bilinguals showed an earlier appearance of IOR than did low-proficient bilinguals, suggesting increased efficiency in disengagement of attention from task-irrelevant inputs. Furthermore, consistent with the "global" advantage that characterizes bilinguals in many tasks, the high-proficient group outperformed low-proficient bilinguals in overall reaction time.     

Language and Cognitive Predictors of Lexical Selection in Storytelling for Monolingual and Sequential Bilingual Children

The primary purpose of the present study was to test language and cognitive predictors of lexical selection in the storytelling of monolingual and bilingual children. Measures of language proficiency and cognitive ability were assessed with both English- and Mandarin-speaking monolinguals and Mandarin-English bilinguals aged 4 to 6 years old. To elicit stories, children watched a cartoon and told the story back. Bilinguals did these tasks in both of their languages. The results showed that the bilinguals told stories with as many different words as monolinguals of both languages but scored lower on measures of vocabulary. For monolinguals, vocabulary score was an important predictor of lexical variety even after controlling for age. For bilinguals, attentional control was a significant predictor of lexical variety in their second language, English. These results suggest that for monolingual children, vocabulary size is an important predictor of lexical variety in stories, while bilingual children might rely more on cognitive abilities to lexicalize concepts.     

Language proficiency and executive control in proactive interference: evidence from monolingual and bilingual children and adults

Two studies are reported in which monolingual and bilingual children (Study 1) and adults (Study 2) completed a memory task involving proactive interference. In both cases, the bilinguals attained lower scores on a vocabulary test than monolinguals but performed the same on the proactive interference task. For the children, bilinguals made fewer intrusions from previous lists even though they recalled the same number of words. For the adults, bilinguals recalled more words than monolinguals when the scores were corrected for differences in vocabulary. In addition, there was a strong effect of vocabulary in which higher vocabulary participants recalled more words irrespective of language group. These results point to the important role of vocabulary in verbal performance and memory. They also suggest that bilinguals may compensate for weaker language proficiency with their greater executive control to achieve the same or better levels of performance as monolinguals.     

Components of executive control with advantages for bilingual children in two cultures

The present study used a behavioral version of an anti-saccade task, called the ‘faces task’, developed by [Bialystok, E., Craik, F. I. M., & Ryan, J. (2006). Executive control in a modified anti-saccade task: Effects of aging and bilingualism. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32, 1341-1354] to isolate the components of executive functioning responsible for previously reported differences between monolingual and bilingual children and to determine the generality of these differences by comparing bilinguals in two cultures. Three components of executive control were investigated: response suppression, inhibitory control, and cognitive flexibility. Ninety children, 8-years old, belonged to one of three groups: monolinguals in Canada, bilinguals in Canada, and bilinguals in India. The bilingual children in both settings were faster than monolinguals in conditions based on inhibitory control and cognitive flexibility but there was no significant difference between groups in response suppression or on a control condition that did not involve executive control. The children in the two bilingual groups performed equivalently to each other and differently from the monolinguals on all measures in which there were group differences, consistent with the interpretation that bilingualism is responsible for the enhanced executive control. These results contribute to understanding the mechanism responsible for the reported bilingual advantages by identifying the processes that are modified by bilingualism and establishing the generality of these findings across bilingual experiences. They also contribute to theoretical conceptions of the components of executive control and their development.     

Bilingualism,executive control,and age at diagnosis among people with early‐stage Alzheimer's disease in Wales

The observation of a bilingual advantage in executive control tasks involving inhibition and management of response conflict suggests that being bilingual might contribute to increased cognitive reserve. In support of this, recent evidence indicates that bilinguals develop Alzheimer's disease (AD) later than monolinguals, and may retain an advantage in performance on executive control tasks. We compared age at the time of receiving an AD diagnosis in bilingual Welsh/English speakers (n = 37) and monolingual English speakers (n = 49), and assessed the performance of bilinguals (n = 24) and monolinguals (n = 49) on a range of executive control tasks. There was a non‐significant difference in age at the time of diagnosis, with bilinguals being on average 3 years older than monolinguals, but bilinguals were also significantly more cognitively impaired at the time of diagnosis. There were no significant differences between monolinguals and bilinguals in performance on executive function tests, but bilinguals appeared to show relative strengths in the domain of inhibition and response conflict. Bilingual Welsh/English speakers with AD do not show a clear advantage in executive function over monolingual English speakers, but may retain some benefits in inhibition and management of response conflict. There may be a delay in onset of AD in Welsh/English bilinguals, but if so, it is smaller than that found in some other clinical populations. In this Welsh sample, bilinguals with AD came to the attention of services later than monolinguals, and reasons for this pattern could be explored further.     

第二语言水平对双语者语言抑制能力的影响——来自英语–汉语单通道双语者和英语–美国手语双通道双语者的证据

采用同形异义词干扰任务考察第二语言水平对英语–汉语单通道双语者和英语–美国手语双通道双语者语言抑制能力的影响。结果发现:(1)高水平英语–汉语单通道双语者的语言抑制能力较强,但低水平英语–汉语单通道双语者与英语单语者的语言抑制能力没有显著差异,说明少量的双语经验不足以导致双语认知优势;(2)不同水平的英语–美国手语双通道双语者的语言抑制能力差异不显著。所以如此,与英语–美国手语双通道双语者不存在口语和手语的双语表征加工竞争有关。整个研究表明,双语认知优势效应与双语者的二语水平以及通道经验有关。     

Effect of language proficiency and executive control on verbal fluency performance in bilinguals

We use a time-course analysis to examine the roles of vocabulary size and executive control in bilinguals’ verbal fluency performance. Two groups of bilinguals and a group of monolingual adults were tested in English with verbal fluency subtests from the Delis–Kaplan Executive Function System. The two bilingual groups were equivalent in their self-rated English proficiency but differed in levels of receptive and expressive vocabulary. We hypothesized that the difference between the two bilingual groups in vocabulary and between the monolingual and bilingual groups in executive control would lead to differences in performance on the category and letter fluency tests and dissociate the roles of vocabulary knowledge and executive control in verbal production. Bilinguals and monolinguals performed equivalently in category fluency, but the high-vocabulary bilingual group outperformed both monolinguals and low-vocabulary bilinguals in letter fluency. An analysis of the retrieval time-course functions in letter fluency showed dissociable effects of resources available at the initiation of the trial, considered to reflect vocabulary size, and ability to monitor and retrieve new items using a novel phonemic-based word searching strategy, considered to reflect executive control. The difference in slope of the best-fitting curves reflected enhanced executive control for both bilingual groups compared to monolinguals, whereas the difference in the starting point of the logarithmic functions reflected higher levels of vocabulary for high-vocabulary bilinguals and monolinguals compared to low-vocabulary bilinguals. The results are discussed in terms of the contributions of linguistic resources and executive control to verbal performance.     

Measuring executive function skills in young children in Kenya

Interest in measuring executive function skills in young children in low- and middle-income country contexts has been stymied by the lack of assessments that are both easy to deploy and scalable. This study reports on an initial effort to develop a tablet-based battery of executive function tasks, which were designed and extensively studied in the United States, for use in Kenya. Participants were 193 children, aged 3–6 years old, who attended early childhood development and education centers. The rates of individual task completion were high (65–100%), and 85% of children completed three or more tasks. Assessors indicated that 90% of all task administrations were of acceptable quality. An executive function composite score was approximately normally distributed, despite higher-than-expected floor and ceiling effects on inhibitory control tasks. Children’s simple reaction time (β = –0.20, p = .004), attention-related behaviors during testing (β = 0.24, p = .0005), and age (β = –0.24, p = .0009) were all uniquely related to performance on the executive function composite. Results are discussed as they inform efforts to develop valid and reliable measures of executive function skills among young children in developing country contexts.     

Bilingual advantage,bidialectal advantage or neither? Comparing performance across three tests of executive function in middle childhood

When bilinguals speak, both fluent language systems become activated in parallel and exert an influence on speech production. As a consequence of maintaining separation between the two linguistic systems, bilinguals are purported to develop enhanced executive control functioning. Like bilinguals, individuals who speak two dialects must also maintain separation between two linguistic systems, albeit to a lesser degree. Across three tests of executive function, we compared bilingual and bidialectal children's performance to that of a monolingual control group. No evidence for a bidialectal advantage was found. However, in line with a growing number of recent partial and failed replications, we observed a significant bilingual advantage only in one measure in one task. This calls the robustness of the bilingual advantage into question. A comprehensive review of studies investigating advantages of inhibitory control and cognitive flexibility in bilingual children reveals that the bilingual advantage is likely to be both task and sample specific, and the interaction between these factors makes qualification of the effect challenging. These findings highlight the importance of tracking the impact of dual linguistic systems across the lifespan using tasks calibrated for difficulty across different ages.     

Novel evidence in support of the bilingual advantage: Influences of task demands and experience on cognitive control and working memory

The bilingual advantage—enhanced cognitive control relative to monolinguals—possibly occurs due to experience engaging general cognitive mechanisms in order to manage two languages. Supporting this hypothesis is evidence that bimodal (signed language–spoken language) bilinguals do not demonstrate such an advantage, presumably because the distinct language modalities reduce conflict and control demands. We hypothesized that the mechanism responsible for the bilingual advantage is the interplay between (a) the magnitude of bilingual management demands and (b) the amount of experience managing those demands. We recruited adult bimodal bilinguals with high bilingual management demands and examined cognitive control and working memory capacity longitudinally. After gaining experience managing high bilingual management demands, participants outperformed themselves from 2 years earlier on cognitive abilities associated with managing the bilingual demands. These results suggest that cognitive control outcomes for bilinguals vary as a function of the mechanisms recruited during bilingual management and the amount of experience managing the bilingual demands.     

The relationship between habitual physical activity status and executive function in individuals with Alzheimer’s disease: a longitudinal,cross-lagged panel analysis

To determine whether habitual physical activity status specifically influences executive function change in Alzheimer’s disease (AD) over 1 year. In this longitudinal cohort study, 45 participants with AD were recruited and provided follow-up data approximately 1 year later. Executive function measures (map search task, digit symbol substitution task, controlled oral word association task, verbal fluency task) and habitual physical activity measures (Physical Activity Scale for the Elderly (PASE) and handgrip strength) were taken at baseline and follow-up. Individual composites were subsequently created. Additional demographic, lifestyle, and neuropsychiatric measures were also taken. In a structural equation model (χ²(26) = 9.84, p = .998, comparative fit index = 1.00, root mean square error of approximation = .00), a significant association was found between habitual physical activity and executive function change (β = .27, p = .04). In a cross-lagged panel analysis, a significant path was found between the PASE score and executive change (β = .22, p = .01). As higher habitual physical activity levels were associated with reduced executive function change, the promotion of low-intensity habitual physical activities in individuals with a diagnosis of AD may be warranted. Further research is needed, however, to explore the impact of habitual physical activity on the trajectory of change across cognitive domains, and how this relates to the progression of the underlying pathology associated with this disease.     

Word Mapping and Executive Functioning in Young Monolingual and Bilingual Children

The effect of bilingualism on the cognitive skills of young children was investigated by comparing performance of 162 children who belonged to one of two age groups (approximately 3- and 4.5-year-olds) and one of three language groups on a series of tasks examining executive control and word mapping. The children were monolingual English speakers, monolingual French speakers, or bilinguals who spoke English and one of a large number of other languages. Monolinguals obtained higher scores than bilinguals on a receptive vocabulary test and were more likely to demonstrate the mutual exclusivity constraint, especially at the younger ages. However, bilinguals obtained higher scores than both groups of monolinguals on three tests of executive functioning: Luria's tapping task measuring response inhibition, the opposite worlds task requiring children to assign incongruent labels to a sequence of animal pictures, and reverse categorization in which children needed to reclassify a set of objects into incongruent categories after an initial classification. There were no differences between the groups in the attentional networks flanker task requiring executive control to ignore a misleading cue. This evidence for a bilingual advantage in aspects of executive functioning at an earlier age than previously reported is discussed in terms of the possibility that bilingual language production may not be the only source of these developmental effects.     

Are bilingual advantages dependent upon specific tasks or specific bilingual experiences?

Paap and Greenberg concluded that there is no coherent evidence for bilingual advantages in executive processing. More optimistic researchers believe that the advantages may be restricted to certain types of bilinguals. Recent large-scale and lifespan investigations that tested highly fluent bilinguals from communities where the same two languages are spoken by most residents reported no bilingual advantages in any age group or in any of the tasks used to measure executive functioning. The present study takes a complementary approach by examining a sample that is quite homogeneous in terms of current life experiences, but heterogeneous in terms of its exposure to second languages. The composite database of 168 bilinguals and 216 monolinguals is used to explore for differences based on: (1) the age of acquiring a second language (L2), (2) the relative proficiency of an L2 and (3) the number of languages used. Across 12 different measures of executive function, derived from 4 different nonverbal tasks, there was no consistent evidence supporting the hypotheses that either early bilingualism, highly fluent balanced bilingualism, or trilingualism enhances inhibitory control, monitoring or switching. In fact, when statistically significant effects did occur, they more often disconfirmed than confirmed these hypotheses.     

工作记忆更新任务中的认知优势效应

目的：采用N-back范式,探讨熟练双语者与非熟练双语者之间工作记忆更新能力的差异,以验证双语优势效应是否存在于工作记忆更新任务中。方法：采用数字型2-back任务,两因素混合实验设计。自变量分别为被试间变量(熟练双语者与非熟练双语者）和被试内变量（低难度任务组和高难度任务组）,因变量为2-back任务中目标刺激、非目标刺激、诱惑刺激和非诱惑刺激的准确率和反应时。结果：熟练双语者与非熟练双语者在低难度的2-back任务（一般的2-back任务）中,目标刺激和非目标刺激的准确率和反应时上没有差异;在高难度任务组（有冲突的2-back任务）中,熟练双语者在非目标刺激、诱惑刺激和非诱惑刺激的准确率显著高于非熟练双语者。结论：工作记忆更新中的“双语优势效应”更容易体现在高执行功能需求的条件下。     

Brain bases of English morphological processing: A comparison between Chinese-English,Spanish-English bilingual,and English monolingual children

How do early bilingual experiences influence children's neural architecture for word processing? Dual language acquisition can yield common influences that may be shared across different bilingual groups, as well as language-specific influences stemming from a given language pairing. To investigate these effects, we examined bilingual English speakers of Chinese or Spanish, and English monolinguals, all raised in the US (N = 152, ages 5–10). Children completed an English morphological word processing task during fNIRS neuroimaging. The findings revealed both language-specific and shared bilingual effects. The language-specific effects were that Chinese and Spanish bilinguals showed principled differences in their neural organization for English lexical morphology. The common bilingual effects shared by the two groups were that in both bilingual groups, increased home language proficiency was associated with stronger left superior temporal gyrus (STG) activation when processing the English word structures that are most dissimilar from the home language. The findings inform theories of language and brain development during the key periods of neural reorganization for learning to read by illuminating experience-based plasticity in linguistically diverse learners.     

No evidence for reduced Simon cost in elderly bilinguals and bidialectals

We explored whether a bilingual advantage in executive control is associated with differences in cultural and ethnic background associated with the bilinguals' immigrant status, and whether dialect use in monolinguals can also incur such an advantage. Performance on the Simon task in older non-immigrant (Gaelic-English) and immigrant (Bengali, Gujarati, Hindi, Malay, Punjabi, Urdu-English) bilinguals was compared with three groups of older monolingual English speakers, who were either monodialectal users of the same English variety as the bilinguals or were bidialectal users of a local variety of Scots. Results showed no group differences in overall reaction times as well as in the Simon effect thus providing no evidence that an executive control advantage is related to differences in cultural and ethnic background as was found for immigrant compared to non-immigrant bilinguals, nor that executive control may be improved by use of dialect. We suggest the role of interactional contexts and bilingual literacy as potential explanations for inconsistent findings of a bilingual advantage in executive control.