¿Hablas español? Parlez-vous français? ni hui shuo zhong wen ma? If you answered “si”,”oui” or ”hui” and you are watching this in English, chances are you belong to the world bilingual and multilingual majority. And besides having an easier time traveling, or watching movies without subtitles, knowing two or more languages means that your brain may actually look and work differently than those of your monolingual friends. So what does it really mean to know a language?
Language ability is typically measured in two active parts, speaking and writing, and two passive parts, listening and reading. While a balanced bilingual has near equal abilities across the board in two languages, most bilinguals around the world know and use their languages in vary proportions. And depending on their situation and how they acquired each language, they can be classified into three general types.
For example, let’s take Gabriella, whose family immigrates to the US from Peru when she was two-years old. As a compound bilingual, Gabriella develops two linguistic codes simultaneously, with a single set of concepts, learning both English and Spanish as she begins to process the world around her. Her teenage brother, on the other hand, might be a coordinate bilingual, working with two sets of concepts, learning English in school, while continuing to speak Spanish at home and with friends.
Finally, Gabriella’s parents are likely to be subordinate bilinguals who learned a secondary language by filtering it through their primary language.
Because all types of bilingual people can become fully proficient in a language regardless of accent and pronunciation, the difference may not be apparent to be a casual observer. But recent advances in imaging technology have given neurolinguists a glimpse into how specific aspects of language learning affect the bilingual brain.
It’s well known that the brain’s left hemisphere is more dominant and analytical in logical processes, while the right hemisphere is more active in emotional and social ones, though this is a matter of degree, not an absolute split.
The fact that language involves both types of functions while lateralization develops gradually with age, has lead to the critical period hypothesis. According to this theory, children learn languages more easilybecause the plasticity of their developing brains let them use both hemispheres in language acquisition, while in most adults, language is lateralized to one hemisphere, usually the left.