Researchers at the University of Luxembourg gathered 21 who all had Luxemburgish (an official language of Luxembourg that developed from a variant of German) as their native language and who studied within the Luxembourgish school system which means they all had German as instruction language and they had all learned French as a second language. The participants then attended secondary school with French as the predominant instruction language. Thus, all of the participants were considered adequately bilingual with the highest proficiency levels in both German and French.
Participants were asked to solve a mixture of simple and complex math problems in both German and French. While participants were able to solve the math problems with equal proficiency in both languages, they took longer on complex tasks and made more errors when working in French.
Participants’ brain activity was measured by functional magnetic resonance imaging which showed that they used different parts of their brains depending on the language in use. Participants used parts of their brain when calculating in French that indicate the need for greater cognitive resources to solve the complexity of the tasks. This also possibly indicated that complex additional solving may have been automatized in German but not French, hence it took more ‘brain power’ to solve the problems in French.
Researchers also found that when solving problems in French, the part of the brain associated with visual presentation also lit up, even though the study had no visual stimuli. “These activations,” the study says, “raise the question of whether bilinguals performed the French complex additions with
the help of a mental visual support, such as via imagining the heard numbers in their visual symbolic form.”
Contrary to previous studies on bilinguals and arithmetic, the brain regions associated with translation were not activated. This indicates that bilinguals are not translating the problems from one language to the other (German to French), but are instead using visio-spacial processing.
“In sum,” the researchers said, “different brain regions can underlie proficient task solving in each of a bilingual’s languages, while behavioral differences are minimal to non-existent.”