bilingualism

Bilingualism refers to the ability to use two languages in everyday life. It encompasses listening, speaking, reading, and writing. Proficiency is uneven across languages and domains and may vary by context. Bilinguals may be simultaneous (acquiring two languages from birth or early childhood) or sequential (acquiring a second language after establishing a first language). Code-switching, or alternating between languages within a conversation, is common and reflects flexible language use rather than confusion.

Bilingual acquisition and development depend on exposure, use, quality of input, and social environment. Simultaneous bilinguals learn two languages from early childhood; sequential bilinguals learn a second language after establishing a first. Language dominance can shift with contexts such as school, work, or family. Language attrition can occur when a language becomes less used.

Cognition and health: Research on cognitive benefits is mixed. Some studies report enhanced executive functions, such as task switching and inhibitory control, particularly in children, but effects are small and not universal. Other studies find no robust advantages. Bilingualism may contribute to cognitive reserve later in life, potentially associated with delayed onset of dementia in some observational studies. Differences in measurement and sample complicate conclusions.

Societal aspects: Bilingualism intersects with education, immigration, and policy. Bilingual education and heritage-language maintenance support cultural identity and access to opportunities. Challenges include unequal access to services, stigma, and language discrimination. Assessing bilingualism often requires looking at functional proficiency across languages and real-world use rather than a single test score.