Bilingualism and age are continuous variables that influence executive function

Revisiting perceptual sensitivity to non-native speech in a diverse sample of bilinguals

Werker and Tees (1984) prompted decades of research attempting to detail the paths infants take towards specialisation for the sounds of their native language(s). Most of this research has examined the trajectories of monolingual children. However, it has also been proposed that bilinguals, who are exposed to greater phonetic variability than monolinguals and must learn the rules of two languages, may remain perceptually open to non-native language sounds later into life than monolinguals. Using a visual habituation paradigm, the current study tests this question by comparing 15- to 18-month-old monolingual and bilingual children's developmental trajectories for non-native phonetic consonant contrast discrimination. A novel approach to the integration of stimulus presentation software with eye-tracking software was validated for objective measurement of infant looking time. The results did not support the hypothesis of a protracted period of sensitivity to non-native phonetic contrasts in bilingual compared to monolingual infants. Implications for diversification of perceptual narrowing research and implementation of increasingly sensitive measures are discussed.

Improvement in executive function for older adults through smartphone apps: a randomized clinical trial comparing language learning and brain training

Bilingualism has been linked to improved executive function and delayed onset of dementia, but it is unknown whether similar benefits can be obtained later in life through deliberate intervention. Given the logistical hurdles of second language acquisition in a randomized trial for older adults, few interventional studies have been done thus far. However, recently developed smartphone apps offer a convenient means to acquire skills in a second language and can be compared with brain training apps specifically designed to improve executive function. In a randomized clinical trial, 76 adults aged 65-75 were assigned to either 16 weeks of Spanish learning using the app Duolingo 30 minutes a day, an equivalent amount of brain training using the app BrainHQ, or a waitlist control condition. Executive function was assessed before and after the intervention with preregistered (NCT03638882) tests previously linked to better performance in bilinguals. For two of the primary measures: incongruent Stroop color naming and 2-back accuracy, Duolingo provided equivalent benefits as BrainHQ compared to a control group. On reaction time for N-back and Simon tests, the BrainHQ group alone experienced strong gains over the other two groups. Duolingo was rated as more enjoyable. These results suggest that app-based language learning may provide some similar benefits as brain training in improving executive function in seniors but has less impact on processing speed. However, future advancements in app design may optimize not only the acquisition of the target language but also the side benefits of the language learning experience.

Examining long-term repetition priming effects in spoken word recognition using computer mouse tracking

Language researchers in a variety of disciplines have used priming as a tool to investigate theoretical questions. In spoken word recognition, long-term repetition priming effects have been obtained across a number of behavioral tasks (e.g., lexical decision, shadowing). Repeated - primed - words are responded to more efficiently than new - unprimed - words. However, to our knowledge, long-term repetition priming effects have not been examined using computer mouse tracking, which would provide data regarding the time course of long-term repetition priming effects. Consequently, we compared participants' lexical decision responses using a computer mouse to primed and unprimed words. We predicted that participants would respond more efficiently to primed words compared to unprimed words. Indeed, across all of the dependent variables investigated (accuracy, reaction time, mouse trajectories) and across environments (in person, online), participants responded more efficiently to primed words than to unprimed words. We also performed additional exploratory analyses examining long-term repetition priming effects for nonwords. Across environments (in person, online), participants had more errors to primed nonwords than to unprimed nonwords, but there were no differences in reaction times and mouse trajectories. The current data demonstrating long-term repetition priming effects in mouse tracking are expected to motivate future investigations examining the time course of various long-term repetition priming effects for both words and nonwords.

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

Alzheimer's disease (AD) is an age-related neurocognitive disorder that is epidemic in the elderly population. Currently, there are limited pharmacological interventions, and this has heightened the urgency to identify potential preventable or modifiable risk factors that promote resilience to the neuropathological effects of AD. The regular use of two or more languages is one such factor that may increases cognitive reserve through the long-standing executive control involved in managing multiple languages in the brain. There is also evidence that bilingualism is associated with increased brain reserve or maintenance, particularly in frontal-executive structures and networks. This review examines the current, sometimes conflicting literature on bi/multilingualism and AD. These studies have confounding variations in the assessment of age of second language onset, language proficiency, language usage, and whether determining incidence of AD or age of symptom onset. Despite these limitations, most publications support the presence of increased frontal-executive reserve that compensates for the development of AD neuropathology and, thereby, delays the emergence of clinical symptoms of dementia by about 4-5 years. Although regularly speaking more than one language does not protect against AD neuropathology, the delay in its clinical expression has a potentially significant impact on the lifelong morbidity from this age-related disease. Learning other languages may be an important modifiable factor for delaying the clinical expression of AD in later life.

Moving beyond response times with accessible measures of manual dynamics

Button-press measures of response time (RT) and accuracy have long served a central role in psychological research. However, RT and accuracy provide limited insight into how cognitive processes unfold over time. To address this limitation, researchers have used hand-tracking techniques to investigate how cognitive processes unfold over the course of a response, are modulated by recent experience, and function across the lifespan. Despite the efficacy of these techniques for investigating a wide range of psychological phenomena, widespread adoption of hand-tracking techniques within the field is hindered by a range of factors, including equipment costs and the use of specialized software. Here, we demonstrate that the behavioral dynamics previously observed with specialized motion-tracking equipment in an Eriksen flanker task can be captured with an affordable, portable, and easy-to-assemble response box. Six-to-eight-year-olds and adults (N = 90) completed a computerized version of the flanker task by pressing and holding a central button until a stimulus array appeared. Participants then responded by releasing the central button and reaching to press one of two response buttons. This method allowed RT to be separated into initiation time (when the central button was released) and movement time (time elapsed between initiation and completion of the response). Consistent with previous research using motion-tracking techniques, initiation times and movement times revealed distinct patterns of effects across trials and between age groups, indicating that the method used in the current study presents a simple solution for researchers from across the psychological and brain sciences looking to move beyond RTs.

Multifactorial approaches to study bilingualism in the aging population: Past, present, future

A better understanding and more reliable classification of bilinguals has been progressively achieved through the fine-tuning methodology and simultaneously optimizing the measurement tools. However, the current understanding is far from generalization to a larger population varying in different measures of bilingualism-L2 Age of acquisition (L2 AOA), L2 usage and exposure, and L2 proficiency. More recent studies have highlighted the importance of modeling bilingualism as a continuous variable. An in-depth look at the role of bilingualism, comparing groups, may be considered a reductionist approach, i.e., grouping based on one measure of bilingualism (e.g., L2 AOA) may not account for variability in other measures of bilingualism (L2 exposure, L2 use or L2 proficiency, amongst others) within and between groups. Similarly, a multifactorial dimension is associated with cognitive performance, where not all domains of cognition and subcomponents are equally influenced by bilingualism. In addition, socio-cultural and demographical factors may add another dimension to the impact of bilingualism on cognitive performance, especially in older adults. Nevertheless, not many studies have controlled or used the multiple socio-cultural and demographical factors as a covariate to understand the role of different aspects of bilingualism that may influence cognitive performance differently. Such an approach would fail to generalize the research findings to a larger group of bilinguals. In the present review paper, we illustrate that considering a multifactorial approach to different dimensions of bilingual study may lead to a better understanding of the role of bilingualism on cognitive performance. With the evolution of various fine-tuned methodological approaches, there is a greater need to study variability in bilingual profiles that can help generalize the result universally.

The Multifaceted Nature of Bilingualism and Attention

Attention has recently been proposed as the mechanism underlying the cognitive effects associated with bilingualism. However, similar to bilingualism, the term attention is complex, dynamic, and can vary from one activity to another. Throughout our daily lives, we use different types of attention that differ in complexity: sustained attention, selective attention, alternating attention, divided attention, and disengagement of attention. The present paper is a focused review summarizing the results from studies that explore the link between bilingualism and attention. For each level of attention, a brief overview of relevant theoretical models will be discussed along with a spotlight on paradigms and tasks used to measure these forms of attention. The findings illustrate that different types and levels of attention are modified by the variety of bilingual experiences. Future studies wishing to examine the effects of bilingualism on attention are encouraged to embrace the complexity and diversity of both constructs rather than making global claims about bilingualism and attention.

Bilingualism and Aging: Implications for (Delaying) Neurocognitive Decline

As a result of advances in healthcare, the worldwide average life expectancy is steadily increasing. However, this positive trend has societal and individual costs, not least because greater life expectancy is linked to higher incidence of age-related diseases, such as dementia. Over the past few decades, research has isolated various protective "healthy lifestyle" factors argued to contribute positively to cognitive aging, e.g., healthy diet, physical exercise and occupational attainment. The present article critically reviews neuroscientific evidence for another such factor, i.e., speaking multiple languages. Moreover, with multiple societal stakeholders in mind, we contextualize and stress the importance of the research program that seeks to uncover and understand potential connections between bilingual language experience and cognitive aging trajectories, inclusive of the socio-economic impact it can have. If on the right track, this is an important line of research because bilingualism has the potential to cross-over socio-economic divides to a degree other healthy lifestyle factors currently do not and likely cannot.

Add Bilingualism to the Mix: L2 Proficiency Modulates the Effect of Cognitive Reserve Proxies on Executive Performance in Healthy Aging

We investigated the contribution of bilingual experience to the development of cognitive reserve (CR) when compared with other, traditionally more researched, CR proxies, in a sample of cognitively healthy senior (60 +) bilingual speakers. Participants performed in an online study where, in addition to a wide inventory of factors known to promote CR, we assessed several factors related to their second language (L2) use. In addition, participants’ inhibitory executive control was measured via the Flanker Task. We used Structural Equation Modeling to derive a latent composite measure of CR informed by traditional CR proxies (i.e., occupational complexity, marital status, current and retrospective socio-economic status, physical exercise, perceived positive support, maximal educational attainment, frequency of leisure activities and extent of social network). We examined whether bilingualism may act as a mediator of the effects of such proxies on cognitive performance therefore assessing the unique contribution of dual language use to CR. First, our analyses revealed facilitatory effects of both L2 age of acquisition and L2 proficiency on the executive performance. Second, our analyses confirmed the moderating role of bilingual experience on the relationship between other factors known to promote CR and cognitive integrity, revealing a strong contribution by bilingualism to CR development. Our findings provide further support to the notion that bilingualism plays an important role in mitigating cognitive decline and promoting successful aging.

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.

Grammatical Aspect and Mental Activation of Implied Instruments: A Mouse-Tracking Study in Persian

Can grammatical cues affect the way people activate event knowledge? We used mouse tracking to study the effect of grammatical aspect on the mental activation of instruments in Persian. Verb aspect is defined as how an action or event is extended over time, whether it is perfective (complete) or imperfective (incomplete). We predicted that imperfective aspect would trigger the mental activation of event knowledge, thus making participants mistakenly believe that the instrument with which the action is normally performed was present in the sentence. We tested this hypothesis using manual action verbs. Fifty female participants read a simple active sentence in which an actor had done or was doing an action (e.g., Sara has sliced/is slicing the zucchinis) with an implied instrument (knife). Then, they were presented with a picture of the implied instrument and judged whether the instrument was mentioned in the sentence they just read by clicking on the PRESENT or ABSENT response option. We predicted that participants would be less efficient at clicking ABSENT in the imperfective condition. In line with this prediction, we found that the imperfective condition caused significant deviation to the incorrect response PRESENT. However, no significant time differences emerged. The results are consistent with embodied views of language comprehension.

Continuous effects of bilingualism and attention on Flanker task performance

Both bilingualism and attention contribute to the development of executive functioning (EF), with higher levels of both leading to better outcomes. The present study treats bilingualism and attention as continuous variables to investigate their impact on EF. Eighty-two 9-year-olds who were attending a French school in an anglophone community completed a flanker task. Children's progress in French represented their level of bilingualism, and attention was assessed through a standard standardized instrument. Degree of bilingualism and degree of attention were both positively related to performance, but exposure to a third language in the home did not further affect outcomes.

Cognitive Persistence and Executive Function in the Multilingual Brain During Aging

Researchers have debated the extent to which the experience of speaking more than two languages induces long-term neuroplasticity that protects multilinguals from the adverse cognitive effects of aging. In this review, I propose a novel theory that multilingualism affects cognitive persistence, the application of effort to improve performance on challenging tasks. I review recent evidence demonstrating that the cingulo-opercular network, consisting of the bilateral inferior frontal gyrus (IFG) and dorsal anterior cingulate cortex (dACC), supports cognitive persistence. I then show that this same network is involved in multilingual language control and changes with multilingual language experience. While both early and late multilinguals exhibit differences in the cingulo-opercular network compared to monolinguals, I find that early multilinguals have a pattern of decreased dACC activity and increased left IFG activity that may enable more efficient cognitive control, whereas late multilinguals show larger dACC responses to conflict that may be associated with higher cognitive persistence. I further demonstrate that multilingual effects on the cingulo-opercular network are present in older adults and have been implicated in the mitigation of cognitive symptoms in age-related neurodegenerative disorders. Finally, I argue that mixed results in the literature are due, in part, to the confound between cognitive persistence and ability in most executive function tasks, and I provide guidance for separating these processes in future research.

Extensive Experience with Multiple Languages May Not Buffer Age-Related Declines in Executive Function

BACKGROUND

Whether bilingualism can improve aspects of cognitive function in late adulthood is hotly debated. A few limited studies have reported that bilingualism may provide a limited buffer against age-related cognitive decline; however, others have not. The present study furthered this inquiry by analyzing the combined effects of age and language experience upon executive function in a geographically diverse online sample.

METHODS

Amazon Mechanical Turk was used to recruit a sample of younger (YA) and older adults (OA) from 24 countries. A total of 81 monolingual participants (YA = 37; OA = 44) and 82 bilingual/multilingual participants (YA = 43; OA = 39) completed task-pure executive function assessments of inhibition, memory updating, and attention switching.

RESULTS

YAs performed better than OAs on both the inhibition and updating tasks. On the attention switching task, a greater switch cost occurred when participants had less time to process a stimulus cue. Notably, no effects of language (i.e., bilingualism) were significant: no main effects or interactions with aging were found for executive function performance.

CONCLUSION

The results of the present study challenge the claim that extensive experience with multiple languages can be a reliably protective factor against some normative age-related declines in executive function.

Employing Natural Control for Confounding Factors in the Hunt for the Bilingual Advantage in Attention: Evidence from School Children in Gibraltar

Does being bilingual convey a benefit in 'cognitive control'? Research on this question has been plagued by confounding geo-political factors which themselves might affect cognitive ability (e.g., Socio-Economic Status, immigration and culture). In the current study, we addressed this problem by exploring individuals of varying degrees of bilingualism from one and the same population, hence naturally controlling for confounding variables. The English/Spanish speaking population of Gibraltar share the same education, amenities, and culture on a very small landmass but vary in the degree to which they master multiple languages. We assessed the performance of 207 Gibraltarian children (9-10 yrs) on a battery of auditory attention tests and captured their degree of bilingualism via self-reported and 'objective' methods. We found at least 'moderate' evidence that measures of bilingualism cannot predict attentional ability. These results add to growing scepticism concerning the truthfulness of the claim that bilingualism conveys cognitive advantages.

Alerting, Orienting, and Executive Control: The Effect of Bilingualism and Age on the Subcomponents of Attention

Life-long experience of using two or more languages has been shown to enhance cognitive control abilities in young and elderly bilinguals in comparison to their monolingual peers. This advantage has been found to be larger in older adults in comparison to younger adults, suggesting that bilingualism provides advantages in cognitive control abilities. However, studies showing this effect have used a variety of tasks (Simon Task, Stroop task, Flanker Task), each measuring different subcomponents of attention and raising mixed results. At the same time, attention is not a unitary function but comprises of subcomponents which can be distinctively addressed within the Attention Network Test (ANT) (1, 2). The purpose of this work was to examine the neurofunctional correlates of the subcomponents of attention in healthy young and elderly bilinguals taking into account the L2 age of acquisition, language usage, and proficiency. Participants performed an fMRI version of the ANT task, and speed, accuracy, and BOLD data were collected. As expected, results show slower overall response times with increasing age. The ability to take advantage of the warning cues also decreased with age, resulting in reduced alerting and orienting abilities in older adults. fMRI results showed an increase in neurofunctional activity in the frontal and parietal areas in elderly bilinguals when compared to young bilinguals. Furthermore, higher L2 proficiency correlated negatively with activation in frontal area, and that faster RTs correlated negatively with activation in frontal and parietal areas. Such a correlation, especially with L2 proficiency was not present in young bilinguals and provides evidence for a bilingual advantage in the alerting subcomponent of attention that characterizes elderly bilinguals' performance. This study thus provides extra details about the bilingual advantage in the subcomponent of attention, in older bilinguals. Consequently, speaking more than one language impacts cognition and the brain later in life.

Retracted: The Effect of Bilingualism on Older Adults' Inhibitory Control: A Meta-Analysis

BACKGROUND AND OBJECTIVES

The effect bilingualism has on older adults' inhibitory control has been extensively investigated, yet there is continued controversy regarding whether older adult bilinguals show superior inhibitory control compared with monolinguals. The objective of the current meta-analysis was to examine the reliability and magnitude of the bilingualism effect on older adults' inhibitory control as measured by the Simon and Stroop tasks. In addition, we examined whether individual characteristics moderate the bilingual advantage in inhibition, including age (young-old vs old-old), age of second language acquisition, immigrant status, language proficiency, and frequency of language use.

RESEARCH DESIGN AND METHODS

A total of 22 samples for the Simon task and 14 samples for the Stroop task were derived from 28 published and unpublished articles (32 independent samples, with 4 of these samples using more than 1 task) and were analyzed in 2 separate meta-analyses.

RESULTS

Analyses revealed a reliable effect of bilingualism on older adults' performance on the Simon (g = 0.60) and Stroop (g = 0.27) tasks. Interestingly, individual characteristics did not moderate the association between bilingualism and older adults' inhibitory control.

DISCUSSION AND IMPLICATIONS

The results suggest there is a bilingual advantage in inhibitory control for older bilinguals compared with older monolinguals, regardless of the individual characteristics previously thought to moderate this effect. Based on these findings, bilingualism may protect inhibitory control from normal cognitive decline with age.

Layers of latent effects in cognitive control: An EEG investigation

Recent research demonstrates that two components of reaching behavior - initiation time (the time elapsed from stimulus presentation to movement initiation) and reach curvature (the degree to which a reach movement deviates from a direct path to the selected response) - exhibit distinct cross-trial dynamics in cognitive control tasks, indicating that these components of behavior reflect two dissociable processes underlying cognitive control: a threshold adjustment process involving the inhibition of motor output and a controlled selection process involving the recruitment of top-down resources to support goal-relevant behavior. The current study investigates the extent to which the cross-trial dynamics previously observed in reaching behavior in the Eriksen flanker task are reflected in event-related potentials during standard button-press responses. Candidate EEG measures of the threshold adjustment process (N2 and Pre-LRP amplitudes) failed to reveal the cross-trial dynamics previously observed in initiation times. Slow wave amplitudes exhibited a close correspondence to the cross-trial dynamics observed in reach curvatures, indicating that the measure is sensitive to some functions of the controlled selection process. Further, LRP slopes presented a close correspondence to the cross-trial dynamics observed in response times, indicating that this measure reflects the combined output of the threshold adjustment process and controlled selection process. The implications of these findings for future research examining the links among behavioral and neural dynamics are discussed.

The Effect of Cognates on Cognitive Control in Late Sequential Multilinguals: A Bilingual Advantage?

The present study investigated the influence of Dutch-German cognates resp. orthographic neighbors on controlled language processing (i.e., response inhibition). Two monolingual Stroop tasks (Dutch and German) were performed by Dutch-speaking participants who could and could not speak German, and by French-speaking participants who could speak German. The question is whether or not cognate language processing affects cognitive control, resulting in a possible bilingual advantage. In the German Stroop task, we found additional advantages in congruent, as well as incongruent, trials for the two Dutch-speaking groups, which postulates the existence of a cognate resp. orthographic neighbor facilitation effect, even when participants only know one of the two cognate languages. The findings are discussed in relation to two possible factors that can modulate the effect of bilingualism on cognitive control: cognateness and orthographic neighborhood. The results suggest the existence of a notification mechanism in the bilingual brain. This mechanism would notify the bilingual brain when dealing with cognates and orthographic neighbors.

Language proficiency does not modulate executive control in older bilinguals

We examined if language proficiency modulates performance in tasks that measure executive control in older Telugu-English bilinguals (n = 50, mean age = 57.15 years). We administered numerical Stroop task, Attention Network Task, Dimensional Change Card Sorting task, and stop-signal task that are known to tap into different aspects of executive functioning on healthy aging Telugu-English bilinguals. Second language (English) proficiency was calculated as a cumulative score that considered both subjective and objective measures of L2 fluency and use. Bilinguals were divided into two groups based on the cumulative score and compared on each task. We did not find any effect of language proficiency on any of the executive control measures. The additional Bayesian analysis also supported these findings. Therefore, the results do not support the claim that bilingual language proficiency modulates executive control, at least in the elderly population. We discuss the results with regard to the issue of bilingual advantage in executive control and the role of age and language use.

Measuring the Timing of the Bilingual Advantage

Empirical evidence has supported the idea that the bilingual advantage is a question of nuanced differences between bilinguals and monolinguals. In this article, I review findings from studies using eye tracking, mouse tracking, and event-related potentials (ERPs) which are particularly suited to measure time. Understanding the timing of the processes underlying executive function is crucial in evaluating the intricacies of the bilingual mind. Furthermore, I provide recommendations on how to best use these timing techniques to compare bilinguals and monolinguals. Temporal differences can characterize ongoing discussions of the bilingual advantage and help explain conflicting findings. Methodological and analytical innovations to better investigate the timing of the cognitive processes at play will inform a wide range of areas in cognitive science.