Bilingualism and cognition

Scientific interest in the effects of (individual) bilingualism on cognition dates back to at least the first quarter of the 20th century, as illustrated by two articles that were published in 1923 on the relation between bilingualism and mental development (Smith, 1923) and between bilingualism and intelligence (Saer, 1923). In addition to engaging scientists, the question of whether and how bilingualism affects cognition also concerns policy makers, educators, and parents of bilingual families. The reason for this widespread interest in this issue plausibly is the high incidence of bilingualism and the appreciation that knowing about the way in which bilingualism affects cognition is a prerequisite for creating the circumstances that foster any of its beneficial effects on cognitive functioning while at the same time preventing any adverse effects it might have. In one domain of cognition, namely, language representation and use, the influence of bilingualism is ubiquitous, affecting all components of the language system, but there is also plenty of evidence to suggest that bilingualism affects nonlinguistic cognitive domains as well. In this entry the influence of bilingualism on language (verbal cognition) will first be discussed and, next, its effect on various aspects of nonverbal cognition