語言學習能力是否會隨著年齡的增長而變?nèi)?學習語言的黃金年齡是多少?最新的研究也許可以給你答案。一項超過60萬人參與的大規(guī)模研究顯示，直到18歲，人們?nèi)匀荒芎芎玫亓暤玫诙�語言。當然，對于已經(jīng)成年的你來說，這不是不好好學英語的借口——雖然很難把英語學得像母語那樣溜，但成年人還是可以學到很不錯的程度。

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 linguistics studies ever conducted—a viral internet survey that drew two thirds of a million respondents—researchers from three Boston-based universities showed children are proficient 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 fluency of a native speaker.

年齡越大，想像巴黎人一樣流利的學說法語就越難。但是究竟存不存在一個關鍵的時間點：過了這個時間點，語言的習得就會很難，以至于我們沒辦法理解其他語言中的基礎語法?來自波士頓的三所大學的研究者為此在互聯(lián)網(wǎng)進行了一項調(diào)查，這項調(diào)查吸引了超過60萬人的參與，是史上最大型的語言學研究之一。研究表明：人們直到18歲都仍然能很好地習得第二語言，比之前的估計推遲10年。但是研究同時指出，如果想把第二語言說的像當?shù)厝艘粯恿骼�，最好�?0歲之前就開始學習。

To parse this problem, the research team, which included psychologist Steven Pinker, collected data on a person’s current age, language proficiency and time studying English. The investigators 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.

為了分析這個問題，研究團隊需要收集的信息有：受調(diào)查者的年齡、語言流利程度、開始學習英語的時間等。研究人員們他們計算得出，為了更客觀地得到這個關鍵時間點，他們需要超過50萬份數(shù)據(jù)。鑒于數(shù)據(jù)量龐大，研究團隊把調(diào)查目標轉(zhuǎn)到了互聯(lián)網(wǎng)。談及這項調(diào)查為什么能得到這么多人的支持時，主要研究者之一，波士頓學院的心理學助理教授Josh Hartshorne分享了他們的經(jīng)驗。

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

他們開發(fā)了一套名為“Which English?”的線上測試，測試內(nèi)容包括代詞，介詞和關系從句等一些基礎的語法。由于各地英語語法存在一些差異，所以在答題者回答完問題后，算法就能預測答題者的母語以及所屬的英語方言區(qū)。例如，一些問題中會包含芝加哥人認為不太對而馬尼托人覺得一點問題都沒有的短語。

The researchers got a huge response by providing respondents with “something that is intrinsically rewarding,” says Josh Hartshorne, an assistant professor of psychology 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 awesome!’ 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，這種預測能給答題者一種激勵。比如說，如果算法預測對了答題者的出身、背景，答題者就會覺得“天啊，現(xiàn)在的科技好帥啊!”;如果預測錯了，回答者也不會覺得沮喪，反倒會有：“哈哈，機器人也不過如此。”一類的想法�？傊疅o論預測效果如何，這都是非常有意思的，回答者會樂意去和朋友分享這個測試。

Hartshorne’s tactic 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.

實踐證明， Hartshorne教授這個主意起到了很好的效果。這個測試在最高峰的一天有10萬的點擊量，在Facebook上總計被分享了30萬次，在reddit登上了首頁，在4chan成為了熱搜話題。人們就這個算法如何從測試題中判斷出回答者的方言區(qū)討論得不亦樂乎。最終，總共有說38種語言的當?shù)厝藚⑴c了進來，其中包括了芬蘭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.

基于參與者的答題情況和他們提供的英語學習的信息，研究者們發(fā)展了一套模型，用于估算把英語學到流利所花的時間以及開始學習新語言的最佳年齡。他們得到的結(jié)論是，習得一門新語言的能力(最起碼學好語法)在18歲之前是最強的;18歲之后就會有斷崖式的下降。而要想完全流利地說一門語言，最好在10歲前開始學習。

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-time. 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 interfere 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.

為什么18歲以后語言學習能力會出現(xiàn)那么大的下滑呢?研究人員認為主要有以下三個原因：社會環(huán)境的變化、第一語言的影響和大腦的發(fā)育。18歲通常是人們從高中畢業(yè)，進入大學學習或參加工作的時間點，此后他們將不再像小時候一樣有學習第二語言的時間、機會及學習環(huán)境。另外，人們在習得第一語言后，第一語言的語法、發(fā)音等會干擾我們?nèi)ソ邮芤环N新的語言。最后，由于18-20歲期間，人類大腦的持續(xù)變化也會加大學習第二語言的難度。

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 prior research places the critical period for speech sounds even earlier.

當然這并不意味著我們在20歲以后就不能去學習新的語言：我們身邊就有大量的人都在那以后學習成功，這是因為我們學習新詞匯的能力是不變的。但是大多數(shù)人在20歲以后就沒辦法像母語一樣地學習一門新的語言：沒辦法接受新的語法規(guī)則或沒辦法說得很自然。當然了，因為這個測試是筆試，無法得知答題者得發(fā)音情況，但是之前得研究都表明，口語水平的分水嶺只會在這之前。

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 Mandarin.

另外，盡管這項研究只研究了英語，研究者們相信這個研究模式可以推廣到其他語言中去。他們現(xiàn)在正在計劃對西班牙語和漢語做類似的研究。

Perhaps even more important than when one learns a language is how. People who learned via immersion—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.”

而對于廣大語言學習者來講，知道“怎么學”來得比“什么時候?qū)W”更重要一些。數(shù)據(jù)表明，90%以上的時間沉浸式生活在講英語的國家里的英語學習者明顯比僅在課堂上學習的人們說得更流利。Hartshorne教授則表示，如果有機會從更早地開始上語言課或稍晚些去生活在講英語的國家里中選擇，他會選擇后者。因為數(shù)據(jù)顯示，沉浸在英語的生活環(huán)境里影響實在太大了，甚至可以很大程度彌補年齡上的弱勢。

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 versus 20 years. The finding is consistent for both native and non-native speakers.

不僅如此，這項研究還有更令人驚訝的發(fā)現(xiàn)，那就是，如果我們想完全掌握一門語言，即使是母語，也要花上三十年以上。因為調(diào)查的對象中，學了30年的人比起學20年的人，仍然有著微小的進步(盡管可能只高出1分)。而且，這種進步在母語和非母語學習者身上是一樣的。

Charles Yang, a computational linguist 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.”

來自賓夕法尼亞大學的計算語言學家Charles Yang則表示，18歲這個結(jié)論并不讓他感到驚訝，因為人們在10歲以前通常不會學很復雜的語法規(guī)則。比如說把形容詞轉(zhuǎn)換為名詞，像句法和形態(tài)這樣的細節(jié)我們通常都是在有比較大之后才開始學習的。

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, remains a skeptic. “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.”

當然也有研究人員對研究結(jié)果持異議，來自喬治敦大學的神經(jīng)學專家Elissa Newport教授，結(jié)合她平日里對語言習得的研究，表示“30年才能完全掌握一門語言”這個結(jié)論明顯和其他研究結(jié)果都不一致，有文獻表明學習一門語言的句法和形態(tài)大約需要5年。

Newport says that although the premise 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 assessment of language proficiency to ensure they are really gauging how well people know English.

Newport教授認為出現(xiàn)錯誤結(jié)論的原因在于測度方式選錯了。她也承認60萬的確是個驚人的數(shù)據(jù)，但是即使樣本量大，如果調(diào)查的問題沒設好，一樣沒辦法得到令人信服的結(jié)論。她更傾向于用已有的方式來評估人們的英語水平。

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希望在一個新的在線單詞測試上重現(xiàn)“Which English?”的成功。但他同時也承認這將很難，因為當人們在測試中沒有獲得足夠好的成績得時候，就傾向于不把這個測試分享給別人。而不可避免的將有一半人分數(shù)在平均分以下，這將不利于測試的傳播和進行。