Bilingual Brain: Language, Thought, and Dementia—Exploring How Multilingualism Shapes Memory, Perception, and Society

In this Speaking of Psychology episode, host Kim Mills chats with Dr. Viorica Marian about how bilingualism and multilingualism shape our minds, memories, and view of the world. The conversation covers definitions of bilingual and multilingual, how the brain manages multiple languages, and the surprising cognitive benefits that may delay age-related dementia. The discussion also explores heritage bilingualism, metalinguistic awareness, and the idea that language influences perception and emotion. The episode concludes with thoughts on how artificial intelligence could impact language diversity and what questions remain for future research.

Overview

In this episode of Speaking of Psychology, the conversation centers on the cognitive and societal implications of speaking more than one language. Dr. Viorica Marian, a psychologist and cognitive scientist at Northwestern University, explains that bilingualism and multilingualism go beyond fluency—they involve managing several symbolic systems in memory and everyday communication. The discussion begins with a personal note on how Marian’s own multilingual background informs her research and a broad definition of language as a symbolic system that can include computer code, math, or music when considered through a linguistic lens. The host and guest emphasize that bilingualism and multilingualism are common across cultures and time, and they review how scientists have begun to quantify their effects on the brain and behavior.

“To have another language is to possess another soul.” This epigraph frames the idea that languages filter identity and perception in culturally distinct ways, something Marian returns to as she describes how people may feel like different selves when switching tongues. The conversation then moves to foundational definitions: a bilingual can use two languages, a multilingual more than two, and both can be learned at any age, not just in childhood. The discussion also covers the concept of heritage bilingualism, where a household language may differ from the dominant language of the country, yet still yields the cognitive and social benefits of bilingual experience.