Bilingualism is a multidimensional and dynamic construct, and its definition has always been a complex challenge. More than half the global population, nowadays, is speaking at least two different languages, and several researchers have provided numerous definitions to date. In modern societies, many children grow up in families and communities where communication in more than one language is part of day-to-day life (e.g., Spanish-speaking children in the U.S.). Consequently, many countries and states are called upon to deal with the bilingualism or multilingualism phenomenon, both at a cultural and an educational level. Due to the complexity of its nature, the study of bilingualism relies on several fields within linguistics, psychology, neuroscience, and education. As research suggests, managing multiple languages may result in more pronounced cognitive improvements than other cognitively stimulating activities.
Top1. Introduction
In modern societies, more and more people speak more than two languages and many of these people are exposed to a second language during their early years of life. A growing body of research has recently focused on the relationship between bilingualism and the development of specific cognitive systems, particularly language, executive functions, and cognitive profile in general. Bilingualism and its relation to linguistic and non-linguistic cognitive functioning have been one of the most active areas of research in the last ten years. The current chapter attempts to shed light on the cognitive profile of bilingual populations by presenting empirical evidence.
Bilingualism is a common human characteristic (Hakuta, 2009) and is defined as a speaker's ability to use two languages simultaneously for communication (Verplaetse & Schmitt, 2010). In a simpler definition, in which language use rather than language proficiency was emphasized, Grosjean (1992) defined bilingualism as “the regular use of two (or more) languages”, whereas bilinguals are described as “those people who need and use two (or more) languages in their everyday lives” (p. 51). In addition, depending on the type of linguistic exposure the children have received, several terms have been used in the literature.
Researchers claim that two specific factors seem to play an essential role in terms of classifying different types of bilingualism, i.e., timing and amount of exposure to two (or more) different languages. According to Kohnert et al., (2020), children who must learn and use two languages, either simultaneously from birth or sequentially in early childhood, can be classified as bilinguals. Therefore, bilingual individuals are those who “rely on two languages for meaningful interactions”. An alternative classification of bilingual children has been proposed, based on the age of second language (L2) acquisition. This classification places children in two different categories, i.e., the «simultaneous bilingual children”, who are exposed to two languages from birth or shortly after (up to three years of age), and the “consecutive bilingual children”, who begin second language acquisition after having already made significant progress in their mother tongue (Riva et al., 2021). Kovelman, Baker, and Petitto (2008) classified bilingual children using the terms “early bilinguals (EBs)” and “late bilinguals (LBs)”. Their classification was based on the criterion of age (i.e., before or after the age of 3–4) during which the first bilingual exposure occurred, which refers to the actual timing in which a bilingual child first begins to receive intensive, regular, and continued exposure to his/her new language. This distinction has also been supported by studies, which found that children who have already mastered linguistic competence in their mother tongue and are exposed to a second language after the age of 4, did not show a native-like pattern of activity in a second language (Jasinska & Petitto, 2013; Perani et al., 2003). Generally, there seems to be a level of disagreement among researchers, as regards the critical age for second language (L2) acquisition; some argue that during the first years of life, the learning of the second language (L2) is almost comparable to that of their mother tongue (L1), while others have identified the age of seven as critical (Jasinska & Petitto, 2013).