Bilingualism, trilingualism or multilingualism is a common reality in India — most literate people can read and write in more than one language, and almost everyone can speak or at least understand several at once. In other predominantly English-speaking parts of the world, multilingual people are often exclaimed at and lauded, but for most Indians, it’s a characteristic that’s inherently a part and parcel of growing up in a country with 22 official languages and hundreds of dialects.

A common question posed to people who speak more than one language is what language they think in. Famous linguist Francois Grosjean writes that most thinking often occurs without language, in “mentalese,” which he describes as “prelinguistic.” Thoughts often translate into particular languages when they’re either “self-talk” — a dialogue directed one’s own self — or when the thoughts are on the verge of being converted into speech. Here, bi- or multilingual people often “use their languages for different purposes, in different domains of life, to accomplish different things. Their level of fluency in a language depends on their need for that language,” Grosjean writes. Any thinking that happens within the confines of language, then, is dependent on what the individual is thinking about. For me, communication with my grandmother will be anticipated in Gujarati; any work email will be formed in English; any weekend plans will be made in Hindi, or in a mixture of Hindi and English.

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As for inner speech, or “self-talk,” the language that comes in use for multilingual people depends on which language they’re most proficient in at the time, researchers say. Most often, multilingual people tend to conduct inner speech in the language they acquired first, and subsequently, the language in which they have spent most of their lives communicating, researchers add. However, a foreign language, such as English (for non-native speakers) can also be internalized, mainly due to its ubiquitousness — “the more languages a multilingual knew, the more frequently they reported using English in inner speech and the less frequently the [native language] was used. This might be linked to a broader acceptance of the self as multilingual — the more languages a person knows and their multilinguality being more part of and integrated into their selves,” according to a study published in the International Journal of Bilingual Education and Bilingualism.

How do these languages, then, exist together, to swap out as the individual pleases, in the multilingual brain? The switch between languages is not a conscious decision; it’s made easier as “fluent bilinguals seem to have both languages active at all times, whether both languages are consciously being used or not,” according to a study published in Frontiers of Psychology. This is apparent in how bilinguals don’t mix up languages while speaking, or if they do, it’s on purpose, which means there is parallel activity going on between two or more languages “without needing to consciously think about it,” researchers said.

The switch, according to a University of Arizona study, happens not between languages, but between different “sound systems” of the languages. Researchers evaluated 32 Spanish/English-speaking people, all of whom have been bilingual since before they were 8 years old. The participants were asked to identify ‘pa’ and ‘ba’ sounds in words presented to them. Researchers found that while both the sounds exist in English and Spanish, they are produced and perceived differently — “English speakers typically begin to vibrate their vocal chords the moment they open their lips, while Spanish speakers begin vocal chord vibration slightly before they open their lips and produce ‘pa’ in a manner similar to English ‘ba.’ As a result of those subtle differences, English-only speakers might, in some cases, confuse the ‘ba’ and ‘pa’ sounds they hear in Spanish,” co-author of the study and assistant professor of speech Andrew Lotto told Psychological Science.

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Language and Early Child Development

The bilingual speakers who participated in the study demonstrated that they perceived the ‘pa’ and ‘ba’ sounds depending on the individual who uttered the sound — while conversing with a Spanish speaker, for example, the bilinguals kicked into ‘Spanish mode’ and understood the meaning of the sounds in Spanish as ‘pa,’, while in ‘English mode,’ they understood the sounds as ‘ba’ within the English language. Uttering the sounds also takes on a similar categorization, with bilinguals deciding based on context as to how to voice words.

“When most people think about differences between languages, they think they use different words and they have different grammars, but at their base languages use different sounds,” he said, adding “If you learn a second language later in life, you usually have a dominant language and then you try to use that sounds system for the other language, which is why you end up having an accent.”

As debate grows about how the multilingual brain processes and utilizes different languages, in different capacities and with different levels of proficiency, we can at least settle on the benefits of multilingualism: The constant incorporation of language increases mental flexibility, which “strengthens your mental muscle and your executive function becomes enhanced,” Judith F. Kroll, professor of Psychology, Linguistics and Women’s Studies, at Penn State University, said in a statement.