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Inside the bi-dialectal mind and brain: An electrophysiological study on executive functions

Periodic Reporting for period 1 - NeuroBid (Inside the bi-dialectal mind and brain: An electrophysiological study on executive functions)

Reporting period: 2018-03-01 to 2020-02-29

There is a widespread impression in Western societies that monolingualism is the norm, but in fact most people function in multilingual and/or bi-dialectal settings. In Europe, it is estimated that around 54% of the population can functionally use a second language. Equally, the European sociolinguistic landscape suggests that bi-dialectals –speakers of two closely related linguistic varieties, known as dialects- exist across Europe (e.g. in Cyprus with speakers of Cypriot Greek and Standard Modern Greek). Recently, research on how bilingualism affects cognitive and brain functioning has seen a steep increase. Within this body of work, several studies have provided evidence in support to the hypothesis that bilingualism enhances executive control, a set of brain and cognitive processes that include inhibition (the ability to inhibit irrelevant information), working memory (the ability to simultaneously hold and manipulate information in mind) and switching (the skill to flexibly switch between different tasks). However, it is yet not clear from this research whether bilingualism affects specific executive control processes (e.g. inhibition) or whether it has a broader effect across executive control components. In addition, the bilingual benefit has not always been replicated and this led some researchers to challenge its very existence. Finally, relative to bilingualism, bi-dialectalism has so far received very little research attention (at least from a neurocognitive perspective that compares the neurocognitive profile of bi-dialectals to that of bilinguals and monolinguals). Examining bi-dialectals’ neurocognition is all the more urgent as bi-dialectals and dialects are often associated with several negative stereotypes in the communities (e.g. bi-dialectals often under-perform at school with the blame put on their intelligence and dialects are considered inferior forms of speech or careless language when used in education). In this context, NeuroBid aimed to closely examine the effect of bilingualism and bi-dialectalism on executive control. In doing so, we also wanted to establish the neurocognitive profile of bi-dialectals as compared to multilinguals and monolinguals (focusing on executive control) and to determine whether the typological distance between the languages spoken by bilinguals (smaller for bi-dialectals) modulates the bilingual advantage. The final goal was to examine whether bilingualism/bi-dialectalism affect specific cognitive components or the EC network as a whole.
In this report, we present preliminary results, as the work reported has yet not been published. First, at the brain level, we conducted a critical review of past research that investigated the effect of bilingualism on executive control using the Event-Related Potentials (ERP) method from cognitive neuroscience. In this review, we identified 23 published studies. The majority of these studies focused on the N2 and P3, two brain measures associated with executive control. Other brain measures have been also investigated (e.g. Error-Related Negativity, N450) but to a much lesser extent. Most of these studies tested young adults and used inhibition tasks. Our review suggests that there is some consistency only in the findings of bilingualism-related effects on the N2 and the Error-Related Negativity (ERN). There is also some evidence supporting an interpretation of these effects as indicating enhanced cognitive processing. Nevertheless, the existence of some null or even contradictory results in a not so extensive literature suggest that it is yet too early for firm conclusions to be drawn, even for these effects. Moreover, in general, the interpretation of the results from this literature is further complicated by various methodological challenges, some of which have been already discussed in the extant literature on the cognitive effects of bilingualism using behavioural measures. These include the following. (1) The existence of confounding variables; that is, many studies do not convincingly exclude the possibility that the reported bilingualism-related effects might alternatively be attributed to various other factors that are also known to affect executive control but have nothing to do with bilingualism. (2) The use of small sample sizes. (3) The task-specificity of some bilingualism-related effects (e.g. a more negative N2 for bilinguals has been mainly reported for only some but not other inhibition tasks). (4) The fact that in many studies no adequate evidence is provided that the brain measures used are indeed sensitive to executive control processes (e.g. larger N2 for conditions that more heavily depend on inhibition).
Second, we individually tested 164 young adult participants (46 multilinguals, 72 bi-dialectals and 46 monolinguals) in seven executive control tasks tapping into all three executive control processes. Participants’ brain responses were also recorded using the ERP method. Here we focus only on the behavioural data. Preliminary results of the behavioural data reveal the following. First, we find that both multilinguals and bi-dialectals have higher executive control scores than monolinguals. Moreover, both the multilingual and bi-dialectal advantage is found in overall executive control ability and cannot be attributed to a specific executive control component.
Our review of the literature on the effect of bilingualism on executive control using the ERP method indicates that the evidence is yet not clear and convincing enough to conclude a bilingual benefit in executive control (at the brain level). This does not necessarily mean that the bilingual advantage does not exist. It suggests, however, that various methodological issues should be carefully addressed in future research, if we are to gain a better understanding of the bilingual mind and brain through the use of the ERP neuroscientific technique. On the other hand, preliminary results from the behavioural data of our empirical study suggest that multilinguals enjoy an executive control advantage and that this benefit extends even to bi-dialectal speakers. The latter finding indicates that, in terms of executive functioning, bi-dialectals pattern like multilinguals and exhibit a different profile compared to monolinguals. It further shows that typological distance is not a factor relevant to the bilingual executive control advantage. Finally, the results of our empirical study provide preliminary support to theoretical accounts, which suggest that bilingualism has a wider effect across executive control components. We believe that, upon publication, these scientific results will have implications beyond academia. Our results show that being a native speaker of a dialect or bi-dialectalism does not have any negative effect on aspects of non-verbal cognitive functioning. In this respect, they refute several of the negative stereotypes that are often associated with dialects and bi-dialectal speakers. Furthermore, our evidence for a bilingual and a bi-dialectal benefit in some aspects of cognition are potentially relevant to language policy; particularly, they provide some empirical support to Europe’s language policy that considers language learning as a priority and aims for every European to master two other languages in addition to their mother tongue.
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