Being bilingual gives you a lasting boost in executive control.
Verdict: contested
Early studies suggested a cognitive edge, but larger, publication-bias-aware analyses find little or none.
What the evidence shows
A popular research narrative held that constantly switching between languages trains the brain's executive-control system, giving bilinguals better attention and self-control and even delaying dementia. It became a common argument for early language learning.
Closer scrutiny weakened it. Paap & Greenberg (2013) ran a battery of executive-function tasks and found no consistent bilingual advantage. De Bruin et al. (2015) then showed the literature was skewed by publication bias: studies finding an advantage were far more likely to be published than null results presented at the same conferences. Larger, better-controlled studies tend to find small or null effects. Bilingualism has many genuine benefits, but the specific claim of a robust, general executive-control advantage is contested and probably overstated.
Sources
Paap, K. R., & Greenberg, Z. I. (2013). There is no coherent evidence for a bilingual advantage in executive processing.
Cognitive Psychology, 66(2), 232–258
Across many executive-function tasks, bilinguals showed no consistent advantage over monolinguals.
DOI: 10.1016/j.cogpsych.2012.12.002 →de Bruin, A., Treccani, B., & Della Sala, S. (2015). Cognitive advantage in bilingualism: An example of publication bias?.
Psychological Science, 26(1), 99–107
Studies supporting a bilingual advantage were far more likely to be published than null studies, indicating publication bias.
DOI: 10.1177/0956797614557866 →