Is bilingualism related to a cognitive advantage in children? A systematic review and meta-analysis.

systematic review and meta-analysis of studies comparing bilingual and monolingual children

Bilingual and monolingual children

Meta-analysis of an overwhelmingly cross-sectional, non-randomised literature: bilingualism is not assigned, and bilingual and monolingual samples differ systematically in immigration status, socioeconomic position and parental education. The meta-analysis's value is that it applies bias correction and moderator analysis to a field that had accumulated many small positive findings.

No reliable cognitive advantage for bilingual children in executive functioning once study quality and confounding are accounted for; effects cluster around zero. This matters for the age question because "start a second language early for the cognitive benefits" is a far-transfer claim, and it is the claim the evidence least supports.

High for the underlying literature. Whether a child is raised bilingual is determined by family migration and language background, which correlate with parental education and with heritable cognitive ability in both directions across samples.

Converges with the adult literature (large-scale replication failures of the bilingual executive-function advantage, and meta-analyses showing publication-bias-driven inflation). This archive treats far-transfer claims as presumptively absent; the bilingual advantage is a textbook instance.