Bilingual advantages are real but specific: executive function, metalinguistic awareness, and theory of mind — not overall IQ.
2
Code-switching is sophisticated, not confused — children switch languages when one offers a more precise word or better emotional expression.
3
25% minimum exposure threshold: below this, children develop passive understanding but active production lags significantly in the minority language.
Research Data
Bilingual Cognitive Advantage by Domain (Effect Size, vs. Monolinguals)
Relative effect size across 152 studies. Psychological Bulletin meta-analysis (2019); CUHK Bilingualism Centre.
Children need at least ~25% exposure to each language to develop active production — passive comprehension alone develops at lower exposure levels but active speaking lags significantly (University of Houston Child Language Lab).