About 60% of the world’s population is bilingual or multilingual. Managing several languages is a challenging task: Bilinguals often make speech errors allegedly due to interference effects that languages have on each other. How do bilinguals manage several languages within one mind? And how are different languages represented in the bilingual brain? These are the key questions in my program of bilingual research.

One theoretical possibility is that native (L1) and non-native (L2) languages are stored, processed, and organized in separate neuroanatomical systems in the brain. Further, according to this view, bilinguals have a capacity to select/de-select L1 or L2, depending on the communicative situation. An alternative view is that there is a single linguistic neuroanatomical system in the brain that gets activated when any language is used. Bilinguals seem to be in control of what language they speak because they actively inhibit an irrelevant language.

In my research, I combine behavioral, eye-tracking, electrophysiological (EEG/ERP), and neuroimaging (fMRI) methodologies to solve some mysteries of the bilingual mind/brain. On this quest, I discovered strong evidence that bilinguals’ languages are always co-activated. This co-activation of languages takes place even when (i) bilinguals speak typologically dissimilar languages; (ii) L2 is acquired relatively late in life and bilinguals’ L2 proficiency is not high; and even when (iii) local and global contexts cue that only one language is relevant (should be selected). Further, I demonstrated that this co-activation of languages happens at all linguistic levels, down to the level of speech sounds and letters. I also determined that inhibition of an irrelevant language is never strong enough to preclude a bilingual from processing it even when content in the irrelevant language is outside of the bilingual’s conscious awareness. Finally, I examined intricate patterns of activations within the language network in the brain in response to L1 and L2 in three different groups of bilinguals, who varied in their L2 proficiency levels and/or age of acquisition.

The results of neuroimaging studies provided further support to the idea that bilinguals’ languages rely on the common neural resources, although some differences in representations of L1 and L2 were also found.

This research helps us understand types of challenges in neurocognitive computations and executive control functioning that people speaking multiple languages face on daily basis. While the issue of potential neurocognitive advantage(s) of multilingualism is a heated topic of debate in the field, I am currently attempting to probe the validity of this idea in my research. In addition, I explore whether multilingualism might have any positive effect on social communicative abilities of individuals with high autistic and psychopathic feature(s) load.

Olessia Jouravlev is a Postdoctoral Research Associate at the McGovern Institute for Brain Research, MIT

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