New Research Shows Unexpected Side-effect of being Bilingual

Bilingual Brains

are stronger brains

Why do you want to learn English? This is a question that we often ask our students at the beginning of their course, and they usually tell us that their motivation comes from their need to use English for their jobs, to pass the exams necessary for them to get a place at university, in order to travel the world or just because “English is now necessary for life”

English School - language learners

We have yet to meet a student who tells us that their motivation for learning English is driven by a desire to alter the function and structure of their brain and improve their cognitive abilities and to hopefully build up cognitive reserve which will help their brain to age healthily as they get older. And yet this is what is happening when we learn languages. 

“Think about the way that the bilingual mind is organised - there are two possibilities, the first possibility is that the two languages of a bilingual are stored separately and when one language is “turned on” the other language is “turned off”. The second possibility is that both languages overlap and that the brain has an exceptional method of managing the process of selecting one language while simultaneously suppressing the other.”- Dr.Anne-Marie Connolly (Director of Studies, Everest Language School)


Our students will know that this process can be quite difficult, especially when the new language is at the early stages and the dominant mother tongue is very difficult to suppress but as proficiency in the second language increases, this linguistic cognitive control improves. Fully fledged bilinguals don’t even notice the enormous feat of coordination that their brain has achieved when they manage to switch between two languages and two sets of linguistic rules regarding sentence structure, tone, register and everything else that is involved in comprehensible, articulate, appropriate speech.

Researching Bilingual Brains


Learning a new language is like exercise for your brain

During her PhD, Anne-Marie compared the cognitive abilities of early bilinguals (people who learned their second language before age 7) and late bilinguals (people who learned their second language after the age of 12) and found that there was an advantage for late bilinguals.

“This finding may be surprising for some people who might expect that early bilingualism is best - the more time you have speaking and switching between two languages the more “training” your brain gets, it’s a logical theory. However, we attribute our finding [that it is the late bilinguals who have the advantage] to the fact that learning a new language after the age of 12 is a far more cognitively difficult task. The effort that a late bilingual needs to put into suppressing the dominant mother tongue to select the less-dominant new language requires a far more intensive training regime for the cognitive system and this then extends beyond the linguistic system and results in a generalised fortification of the executive control system as a whole.” - Dr.Anne-Marie Connolly (Director of Studies, Everest Language School)

PhD graduation from Trinity College Dublin
Everest Language School’s Director of Studies, Anne-Marie Connolly was recently awarded a PhD from Trinity College Dublin. Her thesis explored the ways that learning languages and becoming bilingual impact upon the development, function and change of basic cognitive abilities.

Bilingualism Promotes healthy cognitive ageing

One of Anne-Marie’s experiments was to investigate the long-term benefits of second language learning. This she did by comparing the cognitive abilities of older adults who were active or passive (they were once bilingual but no longer used both languages regularly)  bilinguals and she found a clear cognitive advantage for the active bilinguals. This finding is in line with research emerging from labs all around the world where bilingualism has been found to be a factor that promotes healthy cognitive ageing and helps to combat cognitive decline and the symptoms of age related disorders such as Alzheimer’s and dementia.


Boosting cognitive control may not be any student’s primary motivation for learning English as a second language but it is interesting to think and learn about what is happening under the surface of their heads as they get to grips with phrasal verbs, the structure of the third conditional and the many other intricacies that are involved in mastering the English language.

Future research at Everest Language School

“Another experiment I did was to try to track the emergence of this advantage in language learners, in other words to try to answer the question ‘how bilingual do you need to be before this kind of cognitive advantage comes online’, to do this I used a test-retest design and tested English language learners before and after a six month intensive language course. To measure their cognitive control I used behavioural psychological tests and EEG (electroencephalogram). I also used extensive questionnaires to capture all of the background elements that may or may not have impacted upon the learners’ progress in learning English and subsequent improvement in executive control. In this experiment the results were less clear than in the first one. Overall I didn’t see any improvement in executive control after 6 months of language learning, however when I split the learners into those who had made the most progress (moved up from beginner to elementary to pre-intermediate to intermediate) versus those who made the least progress (those who moved from beginner to elementary) over the course of six months a slight advantage started to emerge for the high progress learners. This may be an indication of the beginning of the bilingual advantage, and I think that if those learners had stayed another 6 months and allowed me to track them from intermediate to upper-int to advanced then the results would have been clearer. The time window I used was definitely too short. At intermediate level the student is just beginning to be able to use English with some degree of fluency, the struggle to suppress the mother tongue is still very evident and the executive control system in the brain is still very much in training in terms of its role in managing a new language. That being said the data and results are promising and provide an excellent springboard for future research. I hope to refine the parameters of this experiment and repeat it over a longer time window at Everest Language School in the very near future." - Dr.Anne-Marie Connolly (Director of Studies, Everest Language School)

Find below a summary of the 2017 Doctoral Thesis of Anne-Marie Connolly, Titled ‘Exploring Bilingual Cognition in Younger and Older Adults and Second Language Learners’. For more information on any aspect of the thesis please feel free to contact Anne-Marie at

Thesis Summary

There is extensive research investigating the benefits of bilingualism on the ways that basic cognitive abilities develop, function and change throughout the lifespan, particularly from cohorts at either end of the developmental lifespan. The central aspect of the bilingual experience that gives rise to generalised effects on cognitive function comes from the well-documented finding that both languages of the bilingual are jointly active, even in situations where only one language is required. Joint activation produces the processing problem of selecting, attending to and maintaining the target language and inhibiting the non-target language. To manage this conflict the domain-general executive control system is recruited, and through its sustained and persistent exercise it is strengthened.

There is much less evidence from young and middle adulthood, perhaps because this age-group is functioning at their cognitive peak and any effects are thereby masked due to insufficiently sensitive tests. However, this life-stage is the time when individuals are most likely to be globally mobile and participating in periods of immersive living and working in environments where a language other than their native one is spoken. This cohort therefore, despite the challenges, presents a unique opportunity to address aspects of the bilingual experience (such as age of acquisition and level of proficiency) and to track the impact of L2 acquisition on cognitive function in language learners at their cognitive peak.

In Chapter 2, the conceptual, methodological and procedural challenges involved in studying the bilingual advantage are discussed and recent criticisms of the field are addressed. It then details the specifics of the Task- Switching Paradigm and the

behavioural and electrophysiological methods adopted in the studies within this thesis along with the behavioural and electrophysiological components of interest.

Chapter 3 aims to disentangle the impact of age of acquisition on the Bilingual Advantage in young adults who have reached a high level of proficiency and who actively use their L2 on a daily basis. Convergent data from behavioural and electrophysiological measurements of executive control indicates that late acquisition results in the differential reorganising of the networks that support the joint activation of two languages. We observed an overall advantage in late bilinguals on the switch cost which we interpret to be the result of an adaptation in early attentional deployment, as evidenced by an enhanced N1. This, we suggest, has arisen on foot of the additional cognitive effort involved in reaching high proficiency as a late acquisition bilingual.

In Chapter 4 we aspire to track the emergence of the bilingual advantage in young adults learning English as an L2 by examining executive function both behaviourally and electrophysiologically in learners before and after a 6 month period of intensive immersive learning. This study provides insight into the unfolding cognitive skills that accompany gains in L2 proficiency as evidenced by a switch cost advantage observed only in those learners who made greater progress in their language learning. We interpret this to be indicative of separate cognitive effects coming online as differing thresholds of proficiency are exceeded.

Chapter 5 explores aspects of the bilingual advantage in older adults, specifically addressing whether sustained active use of both languages is necessary to maintain the associated cognitive advantage. This study employed a wide range of cognitive tests, including a clinical screening tool, the MoCA and found the bilingual advantage to be present in older adults who have maintained active use of both languages. Furthermore, this Chapter revisits the impact of age of acquisition on the bilingual advantage and provides further evidence for an additional enhancement in late bilinguals.

Finally, Chapter 6 presents a discussion of the contributions and implications of these studies, along with suggestions for the future direction of this work.

Bilingual brains are stronger