Multilingualism
"Pvt. Lloyd A. Taylor, 21-year-old transportation dispatcher at Mitchel Field, New York City, who knows Latin, Greek, Spanish, French, German, and Japanese, studies a book on Chinese. A former medical student at Temple University, he passes two hours a day studying languages as a hobby."
This picture was taken during WW2.
A multilingual person is someone who can communicate in more than one language actively (through speaking, writing, or signing).
Multilingual people can speak any language they write in, but cannot necessarily write in any language they speak.[citation ^needed]
More specifically, bilingual and trilingual people are those in comparable situations involving two or three languages, respectively.
A multilingual person is generally referred to as a polyglot, a term that may also refer to people who learn multiple languages as a hobby.
Multilingual speakers have acquired and maintained at least one language during childhood, the so-called first language (L1).
The first language (sometimes also referred to as the mother tongue) is acquired without formal education, by mechanisms heavily disputed.
Children acquiring two languages in this way are called simultaneous bilinguals.
Even in the case of simultaneous bilinguals, one language usually dominates over the other.
In linguistics, first language acquisition is closely related to the concept of a "native speaker".
According to a view widely held by linguists, a native speaker of a given language has in some respects a level of skill which a second (or subsequent) language learner cannot easily accomplish.
Consequently, descriptive empirical studies of languages are usually carried out using only native speakers.
This view is, however, slightly problematic, particularly as many non-native speakers demonstrably not only successfully engage with and in their non-native language societies, but in fact may become culturally and even linguistically important contributors (as, for example, writers, politicians, media personalities and performing artists) in their non-native language.
In recent years, linguistic research has focused attention on the use of widely known world languages, such as English, as a lingua franca or a shared common language of professional and commercial communities.
In lingua franca situations, most speakers of the common language are functionally multilingual.
The reverse phenomenon, where people who know more than one language end up losing command of some or all of their additional languages, is called language attrition.
It has been documented that, under certain conditions, individuals may lose their L1 language proficiency completely, after switching to the exclusive use of another language, and effectively "become native" in a language that was once secondary after the L1 undergoes total attrition.
This is most commonly seen among immigrant communities and has been the subject of substantial academic study.
The most important factor in spontaneous, total L1 loss appears to be age; in the absence of neurological dysfunction or injury, only young children typically are at risk of forgetting their native language and switching to a new one.
Once they pass an age that seems to correlate closely with the critical period, around the age of 12, total loss of a native language is not typical, although it is still possible for speakers to experience diminished expressive capacity if the language is never practiced.