Is being bilingual good for your brain?
双语能力对你的大脑有好处吗？

Reams of papers have been published on the cognitive advantages of multilingualism. Beyond the conversational doors it can open, multilingualism is supposed to improve “executive function”, a loose concept that includes the ability to ignore distractions, plan complex tasks and update beliefs as new information arrives. Most striking, numerous studies have even shown that bilinguals undergo a later onset of dementia, perhaps of around four years, on average. But some of these studies have failed to replicate, leaving experts wondering whether the effect is real, and if so, what exactly it consists of.

The good news is that it is never too late to start learning a new language, if you want your brain to benefit. A study from 2019 showed that a moderate amount of language learning in adults does not boost things like executive function. But it does mitigate age-related decline.

The biggest benefits seem to come to those who master their second languages fully. That in turn is usually because they have spoken them on a near-daily basis for a long time. A bit of university French does not, unfortunately, convey the same advantages as deep knowledge and long experience. Switching languages frequently in the course of a day (or conversation) may be particularly important. Studies of interpreters and translators have provided some of the strongest evidence for a bilingual advantage. For example they are faster at repeatedly jumping between simple addition and subtraction problems than monolinguals, suggesting generally better cognitive control.

But elsewhere is “a forest of confounding variables”, says Mark Antoniou of Western Sydney University. The child of diplomats, raised in a foreign language abroad, may have cognitive and educational advantages that have nothing to do with bilingualism. At the other end of the socioeconomic ladder, though, studies have found striking evidence that in poorer parts of the world multilingual people show the strongest advantages from speaking several languages. Where schooling is scant, researchers surmise that bilingualism exercises children’s brains in a way that their schooling might not.

Age plays a role too. Studies suggest that the effects of languages on the brain are stronger for young children and the old than they are for young adults. Bilingual tots seem to outperform in cognitive development in the early years, but their monolingual classmates may catch up with them later. One meta-analysis on the topic found that 25 studies of 45 found a bilingual advantage in children younger than six, while only 17 found them in children aged 6-12.
年龄也起着作用。研究表明，语言对大脑的影响对幼儿和老年人比对年轻人更强。双语幼儿在早期似乎在认知发展方面表现更优，但他们的单语同学可能在后来赶上他们。一项关于该主题的元分析发现，在 45 项研究中，有 25 项发现 6 岁以下儿童存在双语优势，而只有 17 项发现 6-12 岁儿童存在双语优势。

At the other end of life, Ellen Bialystok of the York University in Canada, the godmother of the field, has compared the cognitive protection bilingualism offers to that afforded by a slice of holey swiss cheese. Doing other things that are good for the brain, such as exercise, is akin to stacking the slices. Their holes occur in different places, and thus collectively offer greater cognitive protection.
在生命的另一端，加拿大多伦多约克大学的艾伦·比奥尔斯托克（Ellen Bialystok），这个领域的保护神，将双语所能提供的认知保护与一块瑞士奶酪的孔洞所带来的保护进行了比较。做其他有益于大脑的事情，比如锻炼，类似于堆叠这些奶酪片。它们的孔洞出现在不同的位置，因此集体上提供了更大的认知保护。

But all these studies take for granted the uncontroversial mental superpower that you get from language study: being able to talk to people you could not have otherwise. Even if you can’t pick your parents and be fluent from birth, that should be more than enough reason to give it a go.
但是，所有这些研究都默认了语言学习所带来的无可争议的心理超能力：能够与那些你原本无法交谈的人交流。即使你不能选择父母并在出生时就流利，这也应该足以成为尝试的理由。