Multilingual Brains: Study Reveals How Polyglots Process Language

New research sheds light on how our brains process languages, particularly in individuals who speak multiple languages fluently, known as polyglots. The study, published in the journal Cerebral Cortex, involved monitoring brain activity in 34 polyglots using functional magnetic resonance imaging (fMRI).

Increased Activity for Proficient Languages

The study revealed that brain activity in the language processing network increased when polyglots listened to languages they were highly proficient in, compared to languages they knew less well or not at all. This suggests that the brain engages more resources when processing languages that require more effort to understand and generate.

The Native Language Exception

Interestingly, the study found a notable exception. For many polyglots, listening to their native language resulted in a significantly lower brain response compared to other languages they knew well. This decrease was around 25% on average. The researchers believe this is because native languages become so ingrained that processing them requires less neural effort.

Efficiency and Expertise

"Polyglots become experts in their native language from a neural efficiency standpoint," explains co-lead author Olessia Jouravlev, a neuroscientist at Carleton University. "This efficiency reduces the need for the entire language network to activate when processing their native tongue."

Distilling Meaning Drives Brain Response

The study suggests that the brain's response to language is primarily driven by how much meaning is extracted from the input. "The more meaning you can extract, the greater the response in language regions," says co-lead author Saima Malik-Moraleda, a doctoral student at Harvard/MIT. "This explains the exception for the native language, as polyglots are likely more efficient at extracting meaning from it."

Investigating the Language Experts

The study included 34 polyglots, ranging in age from 19 to 71. Their native languages were diverse, encompassing English, French, Russian, Spanish, Dutch, German, Hungarian, and Mandarin Chinese. Researchers monitored their brain activity while they listened to passages in eight languages: their native tongue, three languages with varying proficiency levels, and four unknown languages. The passages included excerpts from Lewis Carroll's "Alice in Wonderland" and biblical stories.

Efficiency and Simplicity

The reduced brain response for the native language was particularly pronounced for participants listening to the simpler biblical stories. This suggests that processing complexity also plays a role in brain activity during language comprehension.

This research, led by the Massachusetts Institute of Technology (MIT), offers valuable insights into how the brain adapts and optimizes language processing based on proficiency and familiarity. By studying the "experts" like polyglots, researchers gain a deeper understanding of the cognitive and neural mechanisms underlying human language.