An international team of researchers, including scientists from the National Research University Higher School of Economics (HSE University), has discovered that knowing a foreign language improves memory performance and enhances automaticity when solving complex tasks. The higher the level of language proficiency, the stronger the effect. The results were published in the journal Brain and Cognition.

Cognitive efficiency refers to the ability to optimally use mental resources while learning or solving various problems. It encompasses processes such as attention, memory, speech, and task-switching, according to Scientific Russia. Studies have shown that speaking two or more languages enhances cognitive efficiency due to the constant need to switch between linguistic systems without mixing them.

Researchers from Russia, Norway, and Italy, with participation from HSE University’s Institute for Cognitive Neuroscience, examined how cognitive efficiency manifests in bilinguals. The experiment involved 45 Russian-speaking bilinguals aged 18–34 who were learning English. Participants performed a series of n-back tasks—a type of computerized game designed to train working memory and intelligence. They had to track sequences of stimuli and identify when the current one matched the one presented n steps earlier. The task ranged in difficulty from 0 to 3, depending on how many steps back the comparison was made. In this experiment, the stimuli were Russian consonants: Б, Г, Ж, К, Л, М, П, Ф, Ч, Ш. Results were measured by accuracy, reaction time, and speed/accuracy tradeoff.

It turned out that participants with a higher level of English proficiency showed less decline in accuracy and speed when completing more difficult tasks. No significant differences were observed for easier tasks (levels 0–2).

“Cognitive efficiency means doing a lot while spending little. But to assess it, we need to look not just at how many tasks are completed versus resources spent — we must also vary the difficulty and observe how the brain copes with increased load,” explained Federico Gallo, a research fellow at HSE University’s Center for Intelligence and Cognitive Well-Being and one of the study’s authors. “In our experiment, bilinguals maintained high working memory performance — both in speed and accuracy — even under higher task complexity, which indicates cognitive efficiency.”

The researchers noted that the positive effects of bilingualism increased with cognitive load.

“This may be because the study involved young adults, whose cognitive abilities are naturally high due to their age. In simpler tasks, bilingualism had no room to show its effects, as the brain didn’t require additional resources. But as the load increased, we observed a different picture,” Gallo added.

Moreover, experienced bilinguals showed distinct speed–accuracy tradeoff patterns depending on task difficulty. Those with lower proficiency tended to prioritize accuracy at levels 1 and 2 (remembering one or two steps back) and shifted toward speed at level 3 (three steps back). More advanced bilinguals shifted toward accuracy only at level 2 and maintained that balance at level 3 — a sign of greater automatization of working memory processes.

The researchers also emphasized that the age at which language learning began and the frequency of its use had little impact on the results. The key factor was the actual proficiency level in the second language.

“Our study shows that learning foreign languages enhances cognitive abilities. It’s not necessary to live in a language environment — all participants lived in Russia and used English according to their personal, professional, and academic needs. The age at which they started learning the language was not a determining factor either: positive effects can emerge even when languages are learned later in life. This makes bilingualism a potentially valuable tool for lifelong cognitive training,” concluded Federico Gallo.