什么时候学习一门新外语不算晚？

Perhaps you've toyed with the idea of learning a second or third language. But as an adult, is learning a new language too monumental of a task to undertake?

Let's look at what we know about language development. Early childhood — infancy until age 5 — is a particularly sensitive period when children's brains are primed to learn language.

According to Thomas Bak, Ph.D., a neuroscientist from the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh, children first learn sounds, and then acquire the basic rules of grammar. Then comes vocabulary, which continues to accumulate throughout life. (Microbiome, microagression, net neutrality, safe space, and Seussian are just a few of the 1000 new words that Merriam-Webster added in 2017.)

From birth through puberty, children learn language rapidly and efficiently due to their naturalbrain plasticity and cognitive flexibility. After puberty, however, language acquisition becomes progressively more difficult, and our ability to learn new languages steadily declines.

There's some individual variability in the age of this decline, Bak says, due to natural ability. But a slight decline does occur in all people at some point, whether it be in their 20s or 30s.

Nienke Meulman, who has published research on age and grammar acquisition effects on the brain, says the adage,"'The later, the harder' is definitely true, but there is no clear cut-off age." Even for late learners it is possible to become proficient in a second language, Meulman says.

Bak, who has conducted research on language and aging, tells Business Insider, "the thing which is most difficult to learn as we age is ... sounds." So while you may become more proficient in speaking and communicating in a second language other than your native language, if it's learned after puberty you won't ever speak with a local accent.

"Very often people are completely focused on the idea to sound like a local, but this is in fact the most difficult aspect," Bak says. While your pronunciation of a language will sound best if you learn it early, building your vocabulary and communicating well in a different language is attainable at any age.

Though it may get more difficult, the benefits of learning a new language are immense.

"Difficult is not a bad thing," Bak says. He compares language use to physical activity, where it may be more difficult to achieve physical health as you age, but the more you work out, the better off you are. And just as the benefits of exercise become more crucial as we age, so too do the cognitive benefits.

Because GPS and smartphones can do so much of our thinking for us, our mental acuity can suffer, especially as we age.

"It's not about making things easy, it's about making things worthwhile," says Bak. And his research supports the notion of how worthwhile language learning can be in later life, and that we can indeed learn all our life.

He tells the story of a woman he met when she was 92. With very little prior foreign language knowledge, she had began studying Russian at the age of 56. At age 75, she went on to write her Ph.D. thesis about Russian poets, and now at age 92 is one of the most acclaimed translators of Russian poetry into English.

"My main message is that it's never too late," says Bak. "The main message is about empowerment."

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你是否曾考虑过学习第二或第三语言?但对成年人而言，学习新语言是否太过艰难?众所周知，儿童在婴幼儿时期(0-5岁)格外敏感，他们的大脑非常擅长学习语言。

爱丁堡大学的神经学家Thomas Bak表示，儿童首先学习语音，其次掌握基本语法规则，然后扩充词汇量——在人的一生中，词汇量会不断地积累。从出生到青春期，由于天生的大脑可塑性和认知灵活性，儿童能够迅速而高效地学习语言。然而，在青春期结束后，学习语言会变得越来越困难，我们学习新语言的能力会逐渐下降。

所有人都无法避免语言学习能力退化的现象，但具体年龄节点存在个体差异——也许是二十岁，也许是三十岁。因此，即便你很晚才开始学习外语，仍然有可能熟练掌握。

随着年龄的增长，最难学习的部分是语音语调。因此，即便你能够熟练运用第二语言进行交流，但如果这门语言习得于青春期之后，那么你将永远无法掌握正宗的口音。很多时候，人们非常注重口音问题，希望说得像本土人一样;但其实，这恰恰是最难的部分。别丧气，虽然学习越早发音越好，但任何年龄都能够积累词汇量、并进行流利的交流。

尽管学习新语言越来越困难，但学习过程益处多多。我们可以将学习语言和锻炼身体进行类比——随着年纪的增长，我们越来越难保持身体健康;话虽如此，但你越锻炼身体，身体状况会越好。年龄越大，锻炼身体越重要，锻炼认知也是如此。如今，GPS和智能手机代替我们思考许多事情，这反而损害了我们的认知敏锐度。当我们日益衰老时，学习语言虽然困难，但却能够锻炼认知。因此，“活到老学到老”这句话非常有道理。

Bak告诉我们，他曾经遇到过一位92岁的老太太。她从56岁起开始学习俄语。75岁时，她完成了一篇关于俄罗斯诗歌的博士论文。如今，她是享有盛誉的翻译家，负责将俄罗斯诗歌翻译成英语。

记住，学习绝不言迟!