[Source:  Science Daily]

Bilingual speakers can switch languages seamlessly, likely developing a higher level of mental flexibility than monolinguals, according to Penn State linguistic researchers.
“In the past, bilinguals were looked down upon,” said Judith F. Kroll, Distinguished Professor of Psychology, Linguistics and Women’s Studies. “Not only is bilingualism not bad for you, it may be really good. When you’re switching languages all the time it strengthens your mental muscle and your executive function becomes enhanced.”
Fluent bilinguals seem to have both languages active at all times, whether both languages are consciously being used or not, the researchers report in a recent issue of Frontiers in Psychology. Both languages are active whether either was used only seconds earlier or several days earlier.
Bilinguals rarely say a word in the unintended language, which suggests that they have the ability to control the parallel activity of both languages and ultimately select the intended language without needing to consciously think about it.
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