语言学习能力是否会随着年龄的增长而变弱？学习语言的黄金年龄是多少？最新的研究也许可以给你答案。一项超过60万人参与的大规模研究显示，直到18岁，人们仍然能很好地习得第二语言。当然，对于已经成年的你来说，这不是不好好学英语的借口——虽然很难把英语学得像母语那样溜，但成年人还是可以学到很不错的程度。

The older you get the more difficult it is to learn to speak French like a Parisian. But no one knows exactly what the cutoff point is—at what age it becomes harder, for instance, to pick up noun-verb agreements in a new language. In one of the largest linguistics³ studies ever conducted—a viral internet survey that drew two thirds of a million respondents—researchers from three Boston-based universities showed children are proficient⁴ at learning a second language up until the age of 18, roughly 10 years later than earlier estimates. But the study also showed that it is best to start by age 10 if you want to achieve the grammatical fluency⁵ of a native speaker.

年龄越大，想像巴黎人一样流利的学说法语就越难。但是究竟存不存在一个关键的时间点：过了这个时间点，语言的习得就会很难，以至于我们没办法理解其他语言中的基础语法？来自波士顿的三所大学的研究者为此在互联网进行了一项调查，这项调查吸引了超过60万人的参与，是史上最大型的语言学研究之一。研究表明：人们直到18岁都仍然能很好地习得第二语言，比之前的估计推迟10年。但是研究同时指出，如果想把第二语言说的像当地人一样流利，最好在10岁之前就开始学习。

To parse⁶ this problem, the research team, which included psychologist Steven Pinker, collected data on a person’s current age, language proficiency⁷ and time studying English. The investigators⁸ calculated they needed more than half a million people to make a fair estimate of when the “critical period” for achieving the highest levels of grammatical fluency ends. So they turned to the world’s greatest experimental subject pool: the internet.

为了分析这个问题，研究团队需要收集的信息有：受调查者的年龄、语言流利程度、开始学习英语的时间等。研究人员们他们计算得出，为了更客观地得到这个关键时间点，他们需要超过50万份数据。鉴于数据量庞大，研究团队把调查目标转到了互联网。谈及这项调查为什么能得到这么多人的支持时，主要研究者之一，波士顿学院的心理学助理教授Josh Hartshorne分享了他们的经验。

They created a short online grammar quiz called Which English? that tested noun–verb agreement, pronouns, prepositions and relative clauses, among other linguistic² elements. From the responses, an algorithm predicted the tester’s native language and which dialect of English (that is, Canadian, Irish, Australian) they spoke⁹. For example, some of the questions included phrases a Chicagoan would deem grammatically incorrect but a Manitoban would think is perfectly¹⁰ acceptable English.

他们开发了一套名为“Which English？”的线上测试，测试内容包括代词，介词和关系从句等一些基础的语法。由于各地英语语法存在一些差异，所以在答题者回答完问题后，算法就能预测答题者的母语以及所属的英语方言区。例如，一些问题中会包含芝加哥人认为不太对而马尼托人觉得一点问题都没有的短语。

The researchers got a huge response by providing respondents with “something that is intrinsically rewarding,” says Josh Hartshorne, an assistant professor of psychology¹¹ at Boston College, who led the study while he was a postdoc at Massachusetts Institute of Technology. The small gift to the respondents was a guess about their background. According to Hartshorne: “If it correctly figures out that you are in fact a German-American, people are like, ‘Oh my god, science is awesome¹²!’ And when it’s wrong, they’re like, ‘Ha ha, stupid robot.’ Either way, it’s entertaining and interesting and something that they can think about and talk about with their friends.”

Hartshorne教授表示，这种预测能给答题者一种激励。比如说，如果算法预测对了答题者的出身、背景，答题者就会觉得“天啊，现在的科技好帅啊！”；如果预测错了，回答者也不会觉得沮丧，反倒会有：“哈哈，机器人也不过如此。”一类的想法。总之无论预测效果如何，这都是非常有意思的，回答者会乐意去和朋友分享这个测试。

Hartshorne’s tactic¹³ worked. At its peak, the quiz attracted 100,000 hits a day. It was shared 300,000 times on Facebook, made the front page of Reddit and became a trending topic on 4chan, where a thoughtful discussion ensued about how the algorithm could determine dialect from the grammar questions. The study brought in native speakers of 38 different languages, including 1 percent of Finland’s population.

实践证明， Hartshorne教授这个主意起到了很好的效果。这个测试在最高峰的一天有10万的点击量，在Facebook上总计被分享了30万次，在reddit登上了首页，在4chan成为了热搜话题。人们就这个算法如何从测试题中判断出回答者的方言区讨论得不亦乐乎。最终，总共有说38种语言的当地人参与了进来，其中包括了芬兰1%的人口。

Based on people’s grammar scores and information about their learning of English, the researchers developed models that predicted how long it takes to become fluent in a language and the best age to start learning. They concluded that the ability to learn a new language, at least grammatically, is strongest until the age of 18 after which there is a precipitous decline. To become completely fluent, however, learning should start before the age of 10.

基于参与者的答题情况和他们提供的英语学习的信息，研究者们发展了一套模型，用于估算把英语学到流利所花的时间以及开始学习新语言的最佳年龄。他们得到的结论是，习得一门新语言的能力（最起码学好语法）在18岁之前是最强的；18岁之后就会有断崖式的下降。而要想完全流利地说一门语言，最好在10岁前开始学习。

There are three main ideas as to why language-learning ability declines at 18: social changes, interference from one’s primary language and continuing brain development. At 18, kids typically graduate high school and go on to start college or enter the work force full-time¹⁵. Once they do, they may no longer have the time, opportunity or learning environment to study a second language like they did when they were younger. Alternatively, it is possible that after one masters a first language, its rules interfere¹⁴ with the ability to learn a second. Finally, changes in the brain that continue during the late teens and early 20s may somehow make learning harder.

为什么18岁以后语言学习能力会出现那么大的下滑呢？研究人员认为主要有以下三个原因：社会环境的变化、第一语言的影响和大脑的发育。18岁通常是人们从高中毕业，进入大学学习或参加工作的时间点，此后他们将不再像小时候一样有学习第二语言的时间、机会及学习环境。另外，人们在习得第一语言后，第一语言的语法、发音等会干扰我们去接受一种新的语言。最后，由于18-20岁期间，人类大脑的持续变化也会加大学习第二语言的难度。

This is not to say that we cannot learn a new language if we are over 20. There are numerous examples of people who pick up a language later in life, and our ability to learn new vocabulary appears to remain constant, but most of us will not be able to master grammar like a native speaker—or probably sound like one either. Being a written quiz, the study could not test for accent, but prior¹⁶ research places the critical period for speech sounds even earlier.

当然这并不意味着我们在20岁以后就不能去学习新的语言：我们身边就有大量的人都在那以后学习成功，这是因为我们学习新词汇的能力是不变的。但是大多数人在20岁以后就没办法像母语一样地学习一门新的语言：没办法接受新的语法规则或没办法说得很自然。当然了，因为这个测试是笔试，无法得知答题者得发音情况，但是之前得研究都表明，口语水平的分水岭只会在这之前。

Although the study was conducted only in English, the researchers believe the findings will transfer to other languages, and they are currently developing similar tests for Spanish and Mandarin¹⁷.

另外，尽管这项研究只研究了英语，研究者们相信这个研究模式可以推广到其他语言中去。他们现在正在计划对西班牙语和汉语做类似的研究。

Perhaps even more important than when one learns a language is how. People who learned via immersion¹⁸—living in an English-speaking country more than 90 percent of the time—were significantly more fluent than those who learned in a class. Hartshorne says that if you have the choice between starting language lessons earlier or learning through immersion later, “I’d learn in an immersion environment. Immersion has an enormous effect in our data—large even relative to fairly large differences in age.”

而对于广大语言学习者来讲，知道“怎么学”来得比“什么时候学”更重要一些。数据表明，90%以上的时间沉浸式生活在讲英语的国家里的英语学习者明显比仅在课堂上学习的人们说得更流利。Hartshorne教授则表示，如果有机会从更早地开始上语言课或稍晚些去生活在讲英语的国家里中选择，他会选择后者。因为数据显示，沉浸在英语的生活环境里影响实在太大了，甚至可以很大程度弥补年龄上的弱势。

In what could be the most surprising conclusion, the researchers say that even among native speakers it takes 30 years to fully master a language. The study showed a slight improvement—roughly one percentage point—in people who have been speaking English for 30 versus¹⁹ 20 years. The finding is consistent for both native and non-native speakers.

不仅如此，这项研究还有更令人惊讶的发现，那就是，如果我们想完全掌握一门语言，即使是母语，也要花上三十年以上。因为调查的对象中，学了30年的人比起学20年的人，仍然有着微小的进步（尽管可能只高出1分）。而且，这种进步在母语和非母语学习者身上是一样的。

Charles Yang, a computational linguist¹ at the University of Pennsylvania, says this finding does not surprise him, given the sophisticated grammar rules that we do not pick up until our teenage years—how to change an adjective into a noun, for instance. “These are going to be very fine-grained details in the language,” he says. “You’re learning new words and you’re learning some morphological endings when you’re quite old, you know, in the teenage years.”

来自宾夕法尼亚大学的计算语言学家Charles Yang则表示，18岁这个结论并不让他感到惊讶，因为人们在10岁以前通常不会学很复杂的语法规则。比如说把形容词转换为名词，像句法和形态这样的细节我们通常都是在有比较大之后才开始学习的。

The enthusiasm for the study is not shared by everyone in the field. Elissa Newport, a professor of neurology at Georgetown University who specializes in language acquisition, remains²⁰ a skeptic²¹. “Most of the literature finds that learning the syntax and morphology of a language is done in about five years, not 30,” she says. “The claim that it takes 30 years to learn a language just doesn’t fit with any other findings.”

当然也有研究人员对研究结果持异议，来自乔治敦大学的神经学专家Elissa Newport教授，结合她平日里对语言习得的研究，表示“30年才能完全掌握一门语言”这个结论明显和其他研究结果都不一致，有文献表明学习一门语言的句法和形态大约需要5年。

Newport says that although the premise²² of the study—seeking critical periods for learning a language—is warranted, she thinks the surprising results emerged because the measure the researchers used is flawed. “Testing 600,000 people doesn’t give you a dependable, reliable outcome” if you’re not asking the right questions, she says. Instead of creating a new test, Newport says she would have preferred the researchers use an existing assessment²³ of language proficiency to ensure they are really gauging²⁴ how well people know English.

Newport教授认为出现错误结论的原因在于测度方式选错了。她也承认60万的确是个惊人的数据，但是即使样本量大，如果调查的问题没设好，一样没办法得到令人信服的结论。她更倾向于用已有的方式来评估人们的英语水平。

Hartshorne is hoping to re-create the success of Which English? in a new online vocabulary test, but says he has struggled to create the same level of viral response because people are less willing to share their results if they perform poorly. “When you find out, ‘I’m in the 99th percentile of vocabulary,’ you’re like, ‘Okay, click, share.’ But you know 50 percent of people are below average. And they’re going to be less likely to want to share that.”

Hartshorne希望在一个新的在线单词测试上重现“Which English？”的成功。但他同时也承认这将很难，因为当人们在测试中没有获得足够好的成绩得时候，就倾向于不把这个测试分享给别人。而不可避免的将有一半人分数在平均分以下，这将不利于测试的传播和进行