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

Do bilinguals have a cognitive advantage? Examining effects of bilingualism and language use on executive control

The daily practice of bilingual language control has been argued to affect both lexical processing and non-verbal executive control in bilingual speakers. On the one hand, bilingualism may slow down lexical processing in both languages. On the other hand, bilinguals have been said to show cognitive advantages compared to monolinguals, for example on inhibition and switching tasks. However, this ‘bilingual advantage’ is hotly debated, can often not be replicated, and language groups have been poorly matched on background variables in previous studies. Furthermore, I examined the reliability of the literature and found evidence for the existence of a publication bias (Chapter 3). This over-representation of positive studies compared to studies with null or negative findings hinders a reliable interpretation of the actual effects of bilingualism. The current thesis therefore aimed to examine possible effects of bilingualism on both lexical processing and executive control. Specifically, I investigated the effects of an understudied, but important feature of bilingualism: language use. Effects of bilingualism have been argued to be largest in older adults. Chapter 4 presents a study discussing inhibition and possible effects of age across various tasks. I show that inhibitory control and age effects depend on task-specific features, including the type of interference, type of stimuli, and processing speed. Next, I present a study (Chapter 5 and 6) examining the relation between bilingualism and both lexical processing and executive control in older adults. Importantly, bilingual and monolingual groups were matched on background variables including immigrant status. I furthermore compared a group of active to inactive bilinguals to assess effects of language use. On a lexical processing task, bilinguals had a disadvantage compared to monolinguals. This effect was modulated by language use, implying that not only language proficiency but also actual language use are needed to explain lexical effects of bilingualism. However, the non-verbal executive control tasks showed no consistent effects of bilingualism or language use on inhibition or task switching. Thus, this study did not replicate positive effects on executive control in older adults. Between-subject comparisons remain problematic as groups can never be matched perfectly. Furthermore, these designs cannot assess a causal effect of bilingualism. Therefore, I conducted another study using behavioural and EEG measurements to test for causal effects of language switching on task switching (Chapter 7). When young bilinguals completed a language-switching task prior to a verbal task-switching paradigm, they showed larger switching costs than after a monolingual naming task. However, this effect of language switching was not found for non-verbal task switching. Language switching may thus have a negative impact on verbal switching, but these effects did not extend to non-verbal executive control. Together, these studies suggest that bilingualism and language use affect lexical processing, but there was no evidence for effects of bilingualism and language use on non-verbal executive control in younger or older adults. In combination with other failed replications and the biased literature, this questions the reliability of cognitive benefits associated with bilingualism. However, executive control is not a unity and its manifestation depends on task-specific features. This task impurity, together with the degree to which participant groups are matched, may explain the inconsistency with which effects of bilingualism on executive control have been observed

Understudied factors contributing to variability in cognitive performance related to language learning

While much of the literature on bilingualism and cognition focuses on group comparisons (monolinguals vs bilinguals or language learners vs controls), here we examine the potential differential effects of intensive language learning on subjects with distinct language experiences and demographic profiles. Using an individual differences approach, we assessed attentional performance from 105 university-educated Gaelic learners aged 21–85. Participants were tested before and after beginner, elementary, and intermediate courses using tasks measuring i.) sustained attention, ii.) inhibition, and iii.) attention switching. We examined the relationship between attentional performance and Gaelic level, previous language experience, gender, and age. Gaelic level predicted attention switching performance: those in higher levels initially outperformed lower levels, however lower levels improved the most. Age also predicted performance: as age increased attention switching decreased. Nevertheless, age did not interact with session for any attentional measure, thus the impact of language learning on cognition was detectable across the lifespan

Lifelong interplay between language and cognition: from language learning to perspective-taking, new insights into the ageing mind

A fundamental question in language research is the extent to which linguistic and cognitive systems interact. The aim of this thesis is to explore that relationship across new contexts and over the entire adult lifespan. This work centers on two branches of empirical research: the first is an investigation into the impact of later-life language learning on cognitive ageing (chapters 2-4), and the second examines the cognitive mechanisms underlying communicative perspective-taking from young adulthood into old age (chapter 5). The results of these chapters demonstrate that changes to one’s linguistic environment can affect cognitive functions at any age, and similarly age-related changes to cognition can affect linguistic abilities, shedding light on the extent to which language and the brain are intricately connected over the lifespan. In the discussion (chapter 6), I consider how this work contributes new insights to the field, opening the door for future research to explore methods of improving cognitive abilities and linguistic behavior in old age

Searching for the bilingual advantage in executive functions in speakers of Hunsrückisch and other minority languages: a literature review

The issue of a bilingual advantage on executive functions has been a hotbed for research and debate. Brazilian studies with the minority language Hunsrückisch have failed to replicate the finding of a bilingual advantage found in international studies with majority languages. This raises the question of whether the reasons behind the discrepant results are related to the language’s minority status. The goal of this paper was to investigate the bilingual advantage on executive functions in studies with minority languages. This is a literature review focusing on state of the art literature on bilingualism and executive functions; as well as a qualitative analysis of the selected corpus in order to tackle the following questions: (1) is there evidence of a bilingual advantage in empirical studies involving minority languages? (2) are there common underlying causes for the presence or absence of the bilingual advantage? (3) can factors pertaining to the language’s minority status be linked to the presence or absence of a bilingual advantage? The analysis revealed that studies form a highly variable group, with mixed results regarding the bilingual advantage, as well as inconsistent controlling of social, cognitive and linguistic factors, as well as different sample sizes. As such, it was not possible to isolate which factors are responsible for the inconsistent results across studies. It is hoped this study will provide an overview that can serve as common ground for future studies involving the issue of a bilingual advantage with speakers of minority languages