In his dystopian novel “Nineteen Eighty-Four,” George Orwell imagined an artificial language, Newspeak, whose restricted grammar and vocabulary were designed to limit the freedom of thought. Although that was clearly an extreme scenario, might those who speak a second language find their thoughts and behavior shaped in some lesser and more benign manner by the words they choose? In his lucid and fascinating book “The Bilingual Brain,” Albert Costa forensically explores how different languages coexist within a single human brain, locked into a functional and perpetual—although sometimes awkward and uncomfortable—embrace.

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