Does Being Bilingual Really Improve Brain Performance?
Speaking two languages does not appear to improve mental control processes, and the tests psychologists use to measure these processes often fail to agree with one another.
Source
Bilingual advantages in executive functioning: problems in convergent validity, discriminant validity, and the identification of the theoretical constructs
What they did
The researchers tested 58 bilingual and 62 monolingual college students using 4 computerized tasks: the antisaccade task, the attentional network test, the Simon task, and a color-shape switching task. From these tests, they calculated 13 separate performance scores designed to measure mental abilities like inhibition, monitoring, and cognitive switching. They then compared the scores between the two groups and analyzed whether a participant's degree of bilingual balance predicted better performance.
What they found
Out of the 13 measures, there was no evidence of a bilingual advantage; instead, the few significant differences actually favored monolinguals on measures like the Simon effect and antisaccade response times. Furthermore, the tests showed incredibly poor convergent validity, meaning that different tasks supposed to measure the exact same mental ability (like inhibition) did not correlate with each other. For example, the relationship between the Simon effect and the flanker effect yielded a weak correlation of only 0.14.
The limits
What it doesn't show
This study does not prove that bilingualism never provides cognitive benefits, as it only looked at young, highly educated university students rather than children or older adults. Additionally, because the tasks themselves failed to correlate with each other, the study highlights that our current tests may not reliably capture general executive functioning. Finally, the research relies on self-reported ratings to determine bilingual proficiency, which might not be as precise as objective language testing.
Key terms
- convergent validity
- The degree to which two different tests designed to measure the same underlying mental concept actually yield similar results.
- executive functioning
- A set of top-down mental processes, including working memory, flexible thinking, and self-control, that help people plan, focus, and multi-task.
- inhibitory control
- The cognitive ability to ignore distractions, suppress habitual responses, and focus on relevant information.
- Simon effect
- A phenomenon where people respond slower and make more errors when a visual stimulus is on the opposite side of the screen as the response key.
- mixing costs
- The performance slowdown that occurs when a person must perform a task in a block containing mixed trials compared to a block with only one task type.
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Quiz yourself
What was the main finding of this study regarding the performance difference between bilingual and monolingual university students on the 13 executive functioning (EF) measures?
Common questions
why does this study contradict previous findings of a bilingual advantage?
Older studies often had small sample sizes, which can inflate the rate of false-positive results. When larger samples or multiple tasks are used, the apparent bilingual advantage frequently disappears.
how did the researchers measure the participants' bilingualism?
Participants self-rated their language proficiency on a 7-point scale, and the researchers calculated a balance score based on the ratio of their weakest to strongest language.
why is the lack of correlation between different tasks a big deal?
If tasks like the Simon and flanker tests are supposed to measure the same brain function (inhibitory control) but do not correlate, it suggests these tests measure specific task habits rather than a general mental ability.
did any demographics other than language predict cognitive performance?
No, demographic variables like video game frequency, parental education, and multitasking habits were very poor predictors of performance across the 13 cognitive measures.
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