September 28, 2018

New Research Shows How Bilingual People Switch From One Language To Another

Scientists have worked out what happens in the brains of multilingual people when they switch from one language to another. And, according to their research, this switch is much easier than previously thought.

Past work has highlighted how the switch between languages increases activity in areas of the brain associated with cognitive control, such as the prefrontal and anterior cingulate cortices. But people didn’t know if this spike in activity was the result of disengaging from the first language, engaging in the second, or both. As reported in the Proceedings of the National Academy of Sciences, the team found that disengaging from one language required the effort but starting to speak in a different one was relatively cost-free.

“A remarkable feature of multilingual individuals is their ability to quickly and accurately switch back and forth between their different languages,” lead author Esti Blanco-Elorrieta, a New York University doctoral candidate, said in a statement. “Our findings help pinpoint what occurs in the brain in this process – specifically, what neural activity is exclusively associated with disengaging from one language and then engaging with a new one.”

To understand how the switch occurred, the team used a technique called magnetoencephalography (MEG) to study brain activity in volunteers fluent in both English and American Sign Language (ASL), who often produce both languages at once.

The participants were shown pictures and had to name what they saw in English, ASL, or both. The people who took part were asked to go from producing both languages to producing only one (switching off), or to move from using just one language to using both (switching on).

“The fact that they can do both at the same time offers a unique opportunity to disentangle engagement and disengagement processes – that is, how they turn languages ‘on’ and ‘off’,” observed Blanco-Elorrieta. “In all, these results suggest that the burden of language-switching lies in disengagement from the previous language as opposed to engaging a new language.”

The team showed that using ASL and English at the same time is no more energetically expensive from a neurobiological standpoint than speaking in a single language. Using both is actually less cognitively costly than using the less dominant one alone, which in this case was ASL.  

The study also gives some interesting insights into multitasking. Recently a study showed that our brains can easily reach full capacity when dealing with difficult tasks. However, we now know that communicating in two complementary languages like English and ASL at the same time is not taxing because it uses the same regions of the brain.