學習沒有「關鍵期」,現在開始就不晚 Old schooled: You never stop learning like a child

The adult brain is far more malleable that we thought, and so learning can be child’s play if you know how.

成年人大腦的可塑性,遠遠超過我們過去的認識。如果掌握了正確的方法,你也能像兒童一樣學習。

Some 36-year-olds choose to collect vintage wine, vinyl records or sports memorabilia. For Richard Simcott, it is languages. His itch to learn has led him to study more than 30 foreign tongues – and he’s not ready to give up.

如果你已經36歲,你很可能喜歡收集上好的葡萄酒、唱片或者體育比賽紀念品。但對於理查德•西姆考特(Richard Simcott)來說,他的收藏品是語言。到目前為止,他已經學會了30多種外語,而且他還不打算就此收手。

During our conversation in a London restaurant, he reels off sentences in Spanish, Turkish and Icelandic as easily as I can name the pizza and pasta on our menu. He has learned Dutch on the streets of Rotterdam, Czech in Prague and Polish during a house share with some architects. At home, he talks to his wife in fluent Macedonian.

我們在倫敦一家飯館裡吃飯的時候,他在葡萄牙語、土耳其語和冰島語之間跳來跳去,說起來就好像我念出餐牌上的披薩和意大利麵名字一樣容易。他在鹿特丹街頭學了德語,在布拉格學了捷克語,在和幾位建築師合租房子的時候學了波蘭語。而他在家裡又跟妻子說一口流利的馬其頓話。

What’s remarkable about Simcott isn’t just the number and diversity of languages he has mastered. It’s his age. Long before grey hairs appear and waistlines expand, the mind’s cogs are meant to seize up, making it difficult to pick up any new skill, be it a language, the flute, or archery. Even if Simcott had primed his mind for new languages while at school, he should have faced a steep decline in his abilities as the years went by – yet he still devours unfamiliar grammars and strange vocabularies to a high level. “My linguistic landscape is always changing,” he says. “If you’re school-aged, or middle-aged – I don’t think there’s a big difference.”

西姆考特掌握的語言數量多、差異大,但他身上最引人矚目的,還是他的年齡。遠在我們白髮出現、腰圍漸粗之前,大腦的認知能力就應當開始退化,讓我們很難再學習新技能,比如說外語、長笛或射箭。儘管西姆考特在上學時就萌生了學外語的念頭,但隨著年齡的增長,他的學習能力理應也會下降。但直到目前為止, 他仍然能夠以很高的頻率,貪婪地吸收著生疏的語法和奇怪的詞彙。「我的『語言景觀』(linguistic landscape)一直在不停變化。」他說,「青春年少也好,已屆中年也罷,我並不覺得人的學習能力會有多大差異。」

A decade ago, few neuroscientists would have agreed that adults can rival the learning talents of children. But we needn’t be so defeatist. The mature brain, it turns out, is more supple than anyone thought. “The idea that there’s a critical period for learning in childhood is overrated,” says Gary Marcus, a psychologist at New York University. What’s more, we now understand the best techniques to accelerate knowledge and skill acquisition in adults, so can perhaps unveil a few tricks of the trade of super-learners like Simcott. Whatever you want to learn, it’s never too late to charge those grey cells.

成年人也能擁有足以與兒童媲美的學習能力?要是放在十年之前,很可能只有極少數神經科學家會支持西姆考特的這番話。但是我們不必過早垂頭喪氣。我們 大腦的潛能其實遠超任何人的想像。紐約大學的心理學家加里•馬庫斯(Gary Marcus)說:「人們太過強調童年『關鍵期』的學習能力了。」但是,現在我們已經知道了提升成年人學習效率的最佳策略,可能也多少瞭解了西姆考特這類 「學習超人」的學習訣竅。總之,無論你想學什麼,現在開始,都不算晚。

The idea that the mind fossilises as it ages is culturally entrenched. The phrase “an old dog will learn no tricks" is recorded in an 18th century book of proverbs and is probably hundreds of years older.

傳統觀念認為,大腦會隨著年齡增長而鈍化,變得越來越不能接受新事物——正如英語裡一條諺語說的:「老狗學不會新把戲」(an old dog will learn no tricks)。這條諺語最早出現在一本18世紀的諺語集裡。而早在那以前,它就可能有數百年的歷史了。

When researchers finally began to investigate the adult brain’s malleability in the 1960s, their results appeared to agree with the saying. Most insights came indirectly from studies of perception, which suggested that an individual’s visual abilities were capped at a young age. For example, restricting young animals’ vision for a few weeks after birth means they will never manage to see normally. The same is true for people born with cataracts or a lazy eye – repair too late, and the brain fails to use the eye properly for life. “For a very long time, it seemed that those constraints were set in stone after that critical period,” says Daphne Bavelier at the University of Rochester, New York.

上世紀60年代,研究者終於開始研究成年人大腦的可塑性,當時他們的發現似乎印證了那條諺語的說法。然而其中大多數發現都並非是對大腦直接觀察所得,而間接來自認知領域。一個發現是,視力會在個體年幼時達到頂峰。如果動物在初生的幾週裡視力受到限制,它們在接下來的一生裡都不能擁有正常的視力。對 於一出生就患有白內障或者弱視的人來說,也是如此。之後再想修復,已經太遲,在這一輩子裡大腦都不能正常地控制眼睛。紐約羅切斯特大學學者達芙妮•巴甫利 爾(Daphne Bavelier)說:「在很長時間裡,人們認為,『關鍵期』過後,這類限制就固定成型、不可更改了。」

These are extreme circumstances, of course, but the evidence suggested that the same neural fossilisation would stifle other kinds of learning. Many of the studies looked at language development – particularly in families of immigrants. While the children picked up new tongues with ease, their parents were still stuttering broken sentences. But if there is a critical period for foreign language learning, everyone should be affected equally; Simcott’s ability to master a host of languages should be as impossible as a dog playing the piano.

當然,上面所舉的都是特例。但是證據顯示,神經鈍化也能夠制約人在其他方面的學習能力。科學家曾做過大量關於語言學習、特別是以移民家庭為對象的研究。研究發現,兒童很容易就能學會新外語,但是他們的父母說起外語來卻總是磕磕絆絆。但是,如果在外語學習上真的存在所謂「關鍵期」的話,應該無人能夠例外才對。但是西姆考特居然能學會那麼多種語言,這就應該像讓狗彈琴一樣,根本就是不可能的事啊。

Bearing this in mind, Ellen Bialystok at York University in Toronto, Canada, recently turned to the US census records, which detailed the linguistic skills of more than 2 million Hispanic and Chinese immigrants. A “critical period” for learning a second language in infancy should have created a sharp difference between those who had moved country in early childhood and those who were uprooted in adolescence. In reality? “There was absolutely no discontinuity,” Bialystok says. Instead, she saw a very gradual decline with age among immigrants – which could reflect differences in environment as much as the adults’ rusty brain circuits. “People talk more slowly and clearly to children in short, simple sentences,” she says. “And the child’s entire social and educational network is organised around that language.”

多倫多約克大學學者愛倫•比亞韋斯托克(Ellen Bialystok)就懷有這樣的疑問。最近她研究了美國人口普查記錄,其中詳細記錄了超過2百萬西班牙和華裔移民的語言能力。如果在人幼年時真的存在學習第二語言的「關鍵期」的話,那麼在小時候就來到美國的人和成年之後才來的人之間,勢必存在著英語能力上的巨大差異。但真實情況又如何呢?比亞韋斯托克 說:「他們之間並沒有什麼鴻溝。」事實上她發現,移民的語言能力是隨著年齡增大而逐漸降低的。與其單單指責大腦,不如說是環境不同所致。「在跟兒童說話時,人們會使用簡單短句,會講得更慢、更清楚。」她解釋說,「而且,兒童所面對的整個社會和教育環境,都在敦促其學習語言。」

Yet while Bialystok’s study suggested that adult brains are more pliable than had once been imagined, there was still the suspicion that children might have the edge in certain skills. Adult learners sometimes find it harder to learn to sing in tune, hit a home run or mimic an accent convincingly. At first glance, the problem might seem to lie in adults’ perception and motor skills. Learning involving these abilities differs from the acquisition of factual knowledge, because it needs us to rewire the eyes, ears and muscles.

比亞韋斯托克的研究顯示出成年人大腦擁有我們前所未知的可塑性,但這仍不能打消這樣的懷疑:在學習某些特定技能方面,兒童可以做得更好。比如,成年人有時會發現他們很難唱對調子、打出本壘打,或者準確模仿口音。若未經過仔細考量,我們很可能會把這類差異歸結到成年人認知和行動能力的退化上。這和單純的學習知識又有不同,因為我們需要動用眼睛、耳朵和肌肉。

It’s something that Marcus can identify with. At the age of 38, he devoted himself to learning the guitar, an experience he detailed in his book Guitar Zero. “My family’s initial response was laughter – but they soon saw I was making progress,” he says. Still, during his research, he attended a musical summer camp for 8 to 15-year-olds. He says he was quicker to catch on to the structure of songs, but his younger bandmates had better coordination and sense of pitch.

馬庫斯就為此拿自己做過實驗:他在38歲開始學習吉他,這段經歷已被他詳細寫入《零起步學吉他:新的音樂家和學習的科學》(Guitar Zero: The New Musician and the Science of Learning)一書。他說:「家人在聽說我要學吉他這個事情之後,哄堂大笑。但是不久他們就發現了我的進步。」在學吉他過程中,他參加了一個面對8至 15歲兒童的音樂夏令營。他說,他能比他的「同學們」更快地掌握樂曲結構,但是那些年輕人則有更好的協調性和樂感。

Yet the available evidence hints that children may not always be inherently better at such tasks. One study by Yang Zhang at the University of Minnesota in Minneapolis that focused on the acquisition of foreign accents in adults suggests we may simply be suffering from poor tuition. When the researchers gave them recordings that mimicked the exaggerated baby talk of cooing mothers, the adult learners progressed rapidly.

還有更有價值的證據:兒童並不是真的能夠學得更好。明尼蘇達大學學者張揚(Yang Zhang。音譯)做過一個關於成人學習陌生口音的研究。研究顯示,成年人的學習效果較差,可能只是因為投入不夠。研究者讓成年人聽模仿母親「咕咕兒語」 (baby talk)的錄音帶,發現被試的學習進展神速。

Nor do adults necessarily fumble over the intricate movements that are crucial for music or sport. When volunteers visiting Virginia Penhune's lab at Concordia University in Montreal, Canada, learned to press keys in a certain sequence, at certain times – essentially a boiled-down version of keyboard practice – the adults tended to outshine the younger volunteers.

在學習音樂和運動所需的複雜運動方面,成年人也不一定處於劣勢。加拿大康科迪亞大學(Concordia University)學者維吉尼亞•本胡恩(Virginia Penhune)找來一批實驗者,讓他們以固定次序、固定次數重複按鍵——這其實是在模仿彈琴訓練。在這個實驗裡,成年被試的表現甚至優於年輕被試。

During a more challenging test of hand-eye coordination, nearly 1000 volunteers of all age groups learned to juggle over a series of six training sessions. As you might expect, the senior citizens aged 60 to 80 began with some hesitation, but they soon caught up with the 30-year-olds and by the end of the trials all the adults were juggling more confidently than the 5 to 10-year-olds.

還有另一個更高難度的、需要手眼協調性的實驗,有將近1000名各年齡段志願者參與。被試通過6個階段訓練,學習變戲法。正如你可能設想的那 樣,60-80年齡組的被試開始時有些遲鈍。但是他們很快就追上了30年齡組的被試。而在全部訓練結束之後,所有成年組的被試在變戲法時都比5-10年齡 組更有自信。

Old dogs, then, are much more adaptable than folklore would have it – and if we do have deficits, they aren’t insurmountable. The reason that children appear to be better learners may have more to do with their environment, and factors such as physical fitness (see “Faster body, faster mind”).

這麼來看,「老狗」的可塑性可比諺語裡說的要大得多。就算我們真的遭遇學習障礙,它也並非不可踰越。兒童看似學東西更好更快,其原因很可能在於他們所處的環境,以及身體健康狀況(請見後文「好的身體帶來好的頭腦」)。

Indeed, many researchers believe that an adult’s lifestyle may be the biggest obstacle. “A child’s sole occupation is learning to speak and move around,” says Ed Cooke, a cognitive scientist who has won many memory contests. “If an adult had that kind of time to spend on attentive learning, I’d be very disappointed if they didn’t do a good job.”

事實上很多研究者相信,成年人的生活方式才是他們學習的最大阻礙。「對於嬰兒來說,他們的任務只是學習說話,以及爬來爬去。」贏得過多次記憶競賽的 認知科學家艾德•庫克(Ed Cooke)如是說,「如果成年人也有相同的時間專心學習,他們也能學得很好。」(關於庫克的更多介紹請繼續閱讀《學會一門語言需要幾個小時?》)

A glut of free time and a carefree existence are out of reach for most of us, but there are other behaviours that boost children’s learning, and these habits can be easily integrated into even an adult’s schedule. For example, children are continually quizzed on what they know – and for good reason: countless studies have shown that testing doubles long-term recall, outperforming all other memory tactics. Yet most adults attempting to learn new skills will rely more on self-testing which, let’s be honest, happens less often.

然而我們大多數人並沒有太多閒暇時間可以心無旁騖地學習。儘管如此,我們也能借鑑一些刺激兒童學習的方法,將之加到我們的日常計劃裡。比方說,老師 在指導兒童學習時總是問他們問題,以鞏固所學。這個方法非常有道理,因為已經有無數研究證明,測試能增強長期記憶,其效果要大大優於其他教學方法。但是對 於想學新東西的成年人來說,他們往往只能進行自我檢測——說實話,這可不常見。

That’s why Cooke developed a website, called Memrise, which helps take some of the pain out of testing and, crucially, can integrate learning into the adult day. It is designed to track your learning curve with cunningly timed tests that force you to retrieve the information just as you are about to forget it.

有鑑於此,庫克建立了一個名為Memrise的網站,幫助成年人規劃自我測試,而且最重要的是,將測試納入他們的時間表。Memrise網站會記錄你的「學習曲線」,在你馬上要忘掉某個知識點的時候,彈出測試題來,讓你能夠重溫記憶。

"Memrise engages your brain to the greatest possible extent," says Cooke, who has himself used the site to learn thousands of words of foreign vocabulary. Users can create their own courses – the topics range from art to zoology – and importantly, it is easy to load the site in the few spare minutes of your lunch break or while you are waiting for a train. Cooke also plans to launch a smartphone app.

庫克說:「Memrise會在最大程度上拓展你的大腦潛能。」他自己就已經利用這個網站學會了數千個外文詞彙。在這裡,用戶可以自行建立課程,題目 五花八門,從藝術到動物學,幾乎無所不包。尤其重要的是,你如果有幾分鐘的空閒時間(比如午休或者等車的時候),就能輕鬆登錄網站,開始學習。而且,庫克 還打算要開發一款智能手機應用程序,使學習更加快捷方便。

What about tasks that involve perceptual learning or motor skills – like battling against a lifetime of tone deafness, or perfecting that golf swing? Here too, there are guiding principles that can help you rediscover the seemingly effortless learning of youth.

但是,還有些學習任務要求認知能力或運動技能,比如告別音痴,或者打出一桿完美的高爾夫。要怎麼達成這類學習任務呢?科學家也同樣為我們提供了指導建議,幫助我們重新找回年輕時代那種什麼都一學就會的感覺。

Adults can hamper progress with their own perfectionism: whereas children throw themselves into tasks, adults often agonise over the mechanics of the movements, trying to conceptualise exactly what is required. This could be one of our biggest downfalls. “Adults think so much more about what they are doing,” says Gabriele Wulf at the University of Nevada, Las Vegas. “Children just copy what they see.”

一個觀點是,成年人往往囿於自己對完美的過分追求。兒童會急於完成任務,但是成年人卻常常為每一步費盡心思,試圖與要求的做到一模一樣——這可能就 是我們面對的最大困難之一。「成年人在做事的時候想得太多,」拉斯維加斯內華達大學的學者加布里埃萊•沃爾夫(Gabriele Wulf)如是說,「兒童卻是看到什麼就照做不誤。」

Wulf’s work over the past decade shows that you should focus on the outcome of your actions rather than the intricacies of the movements. She applies this finding in her own life: as a keen golfer, she has found it is better to think about the swing of the club, for instance, rather than the position of her hands. “I’m always trying to find where best to focus my attention,” she says. Similarly, if you are learning to sing, then you should concentrate on the tone of the voice, rather than on the larynx or the placement of the tongue. Study after study shows that simply shifting your mindset in this way accelerates your learning– perhaps by encouraging the subconscious, automatic movements that mark proficiency.

沃爾夫過去十年的研究證明,我們應當把重點放在行為的效果,而不是複雜的動作步驟上。她將這個理論運用到了自己的生活中:她本人是一個出色的高爾夫 球手,她發現,與不斷注意雙手的位置相比,想著揮杆的感覺的話,就能打出更好的成績。她說:「我在揮杆時,一直在找最佳關注點。」同理,要學唱歌,你就應 該把注意力放到音效上,而不是舌頭的位置或者喉嚨。很多研究證明,只要你稍稍改變關注點,學習效率就能得到提高——其中原因可能在於,如果你將關注點放到 動作的整體感覺而不是細節上,可以讓你的動作在下意識裡變得更純熟。

Misplaced conscientiousness may also lead adults to rely on overly rigid practice regimes that stifle long-term learning. The adult talent for perseverance, it seems, is not always a virtue. Left to their own devices, most people segment their sessions into separate blocks – when learning basketball, for instance, they may work on each shot in turn, perhaps because they feel a desire to master it. The approach may bring rapid improvements at first, but a host of studies have found that the refined technique is soon forgotten.

關注點如果放錯了地方,會導致人們過分追求細節,從而阻礙了整體的學習。成年人不畏艱難、孜孜不倦、追求卓越,但這似乎並不總能帶來優勢。大多數人 喜歡將任務分成小步驟去完成。以學籃球為例,成年人在投每個球時都分外講究,這也許是因為他們有投好每個球的渴望。在開始的時候,這個方法或許能顯著提高 球技,但是大量研究發現,這樣獲得的技能很快就會被忘到腦後。

Instead, you do better to take a carousel approach, quickly rotating through the different skills to be practised without lingering too long on each one. Although the reason is still unclear, it seems that jumping between skills makes your mind work a little harder when applying what you’ve learned, helping you to retain the knowledge in the long term – a finding that has helped people improve in activities ranging from tennis and kayaking to pistol shooting.

與之相反,你可以採用「回轉傳送帶」法,反覆訓練多個技能,而不是在其中一個上下死功夫。來回練習多項技能,似乎能讓你的大腦在學以致用上做得更好,並讓你保有長期的記憶,雖然其中原因還不清楚。這個方法已經幫助人們在網球、皮划艇和手槍射擊上取得了更好的成績。

Such an approach might not be to everyone’s taste – with intricate skills, it might feel like you are making no progress. But even if you do revert to stints of lengthy practice, you can still reap some of the same benefits by occasionally trying out your skills in an unfamiliar situation. In tennis, you might move to a different part of the court for a couple of serves before returning to the regular position; while playing scales on a musical instrument, you might switch hands temporarily. According to work by Arnaud Boutin at the Leibniz Research Centre for Working Environment and Human Factors in Dortmund, Germany, venturing out of your comfort zone in this way helps to ensure that you improve your overall performance rather than confining your progress to the single task at hand. “Otherwise, the longer you practise, the harder it becomes to transfer the skills that you’ve learned to new situations,” says Boutin.

但也許很多人不喜歡這麼做。你可能會覺得,如果不走踏實每一步,怎麼可能會有進步?但就算你還要堅持原來的學習策略,你仍然可以通過不時地在陌生環 境中訓練,來獲得提升。比如在打網球時,與其一直守著一個位置,你可以換到別的位置打幾回合;又比如在彈音階時,你可以偶爾換換手。德國多特蒙德萊布尼茨 研究中心(the Leibniz Research Centre)的學者阿爾諾•柏廷(Arnaud Boutin)曾經做過一個關於工作環境和人為因素的研究。這個研究證明,偶爾離開自己熟悉的區域,而不是將全部精神陷入手頭唯一工作,可以幫助你提升整 體表現。柏廷說:「執迷於一件事情越久,你就越難將學得的技能應用到其他方面。」

If none of that helps you learn like a child, simply adopting the arrogance of youth may do no harm. “As we get older, we lose our confidence, and I’m convinced that has a big impact on performance,” says Wulf. To test the assumption, she recently trained a small group of people to pitch a ball. While half were given no encouragement, she offered the others a sham test, rigged to demonstrate that their abilities were above average. They learned topitch on target with much greater accuracy than those who didn’t get an ego boost.

如果上面這些方法都對你無效,你還可以嘗試讓自己變得更大膽。 沃爾夫說:「我們在成長過程中會逐漸失去自信,而自信與否會對我們的表現產生很大影響。」最近她找來一小群人,做了一個投球實驗來驗證這個理論。她讓其中 一半被試參加了一個偽測試,讓他們以為自己的投球能力勝於常人;而另一半被試就沒這麼「幸運」了。實驗結果是,自信心大增的前一組人,在訓練之後投球的精 準度要遠遠高於另一組人。

Whether your itch to learn will ever match Simcott’s appetite for foreign languages is another matter. “What I do – it’s like an extreme sport. There’s no need to learn that many languages,” he says. He has recently turned to Chinese, and has no plans to stop after that. “I’m like a linguistic butterfly. There’s always another, really far away, that suddenly feels appealing.”

但你的學習熱情能不能比得上西蒙考特對外語的摯愛呢?那就是另一個問題了。西蒙考特說:「我的外語學習,就好像是極限運動。你並不用像我這麼誇張。」最近他又把熱情投向中文,且還不打算收手。 「我就像個語言浪子,總在尋找下一個情人。」

Still, embrace the idea that your mind is as capable as Simcott’s, and the lure of extreme learning might take hold of you too.

但是來試著接受這個觀點吧:其實你的大腦和西蒙考特的沒什麼不同。一旦愛上極限學習,小心收不住!

-by David Robson, New Scientist

 

資料來源:Old schooled: You never stop learning like a child. NeuroscienceStuff Blog [May 26, 2013]

轉載自果殼網「學習之道」主題站