By Kate Fehlhaber

One day in 1995， a large， heavy middle-aged man robbed two Pittsburgh banks in broad daylight. He didnt wear a mask or any sort of disguise. And he smiled at surveillance cameras before walking out of each bank. Later that night， police arrested a surprised McArthur Wheeler. When they showed him the surveillance tapes， Wheeler stared in disbelief. “But I wore the juice，” he mumbled. Apparently， Wheeler thought that rubbing lemon juice on his skin would render him invisible to videotape cameras. After all， lemon juice is used as invisible ink so， as long as he didnt come near a heat source， he should have been completely invisible.

Police concluded that Wheeler was not crazy or on drugs—just incredibly mistaken.

The saga2 caught the eye of the psychologist David Dunning at Cornell University， who enlisted his graduate student， Justin Kruger， to see what was going on. They reasoned that， while almost everyone holds favourable views of their abilities in various social and intellectual domains， some people mistakenly assess their abilities as being much higher than they actually are. This“illusion of confidence” is now called the “DunningKruger effect”， and describes the cognitive bias to inflate self-assessment.

To investigate this phenomenon in the lab， Dunning and Kruger designed some clever experiments. In one study， they asked undergraduate students a series of questions about grammar， logic and jokes， and then asked each student to estimate his or her score overall， as well as their relative rank compared to the other students. Interestingly， students who scored the lowest in these cognitive tasks always overestimated how well they did—by a lot. Students who scored in the bottom quartile3 estimated that they had performed better than two-thirds of the other students！

This “illusion of confidence” extends beyond the classroom and permeates everyday life. In a follow-up study， Dunning and Kruger left the lab and went to a gun range， where they quizzed gun hobbyists about gun safety. Similar to their previous findings， those who answered the fewest questions correctly wildly overestimated their knowledge about firearms. Outside of factual knowledge， though， the Dunning-Kruger effect can also be observed in peoples self-assessment of a myriad4 of other personal abilities. If you watch any talent show on television today， you will see the shock on the faces of contestants who dont make it past auditions5 and are rejected by the judges. While it is almost comical to us， these people are genuinely unaware of how much they have been misled by their illusory superiority.

Sure， its typical for people to overestimate their abilities. One study found that 80 per cent of drivers rate themselves as above average—a statistical impossibility. And similar trends have been found when people rate their relative popularity and cognitive abilities. The problem is that when people are incompetent， not only do they reach wrong conclusions and make unfortunate choices but， also， they are robbed of the ability to realise their mistakes. Instead of being confused， perplexed or thoughtful about their erroneous ways， incompetent people insist that their ways are correct. As Charles Darwin wrote in The Descent of Man（1871）： “Ignorance more frequently begets confidence than does knowledge.”6

Interestingly， really smart people also fail to accurately self-assess their abilities. As much as D- and F-grade students overestimate their abilities， A-grade students underestimate theirs. In their classic study， Dunning and Kruger found that high-performing students， whose cognitive scores were in the top quartile， underestimated their relative competence. These students presumed that if these cognitive tasks were easy for them， then they must be just as easy or even easier for everyone else. This so-called “imposter7 syndrome” can be likened to the inverse of the Dunning-Kruger effect， whereby high achievers fail to recognise their talents and think that others are equally competent. The difference is that competent people can and do adjust their self-assessment given appropriate feedback， while incompetent individuals cannot.

And therein lies the key to not ending up like the witless8 bank robber. Sometimes we try things that lead to favourable outcomes， but other times—like the lemon juice idea—our approaches are imperfect， irrational， inept or just plain stupid. The trick is to not be fooled by illusions of superiority and to learn to accurately reevaluate our competence. After all， as Confucius reportedly said， real knowledge is knowing the extent of ones ignorance.

1995年的一天，一名體格粗壯的中年男子在光天化日之下?lián)尳倭藘砷g匹茲堡的銀行。他沒有戴口罩或是進(jìn)行任何偽裝，而且在走出每間銀行之前，他還朝著監(jiān)控?cái)z像頭微笑了一下。當(dāng)天晚上，警方逮捕了一個(gè)名叫麥克阿瑟·惠勒的嫌犯，被捕時(shí)他一臉驚訝。當(dāng)警方向他展示監(jiān)控錄像時(shí)，惠勒難以置信地瞪大了眼睛。“但是我涂了果汁呀，”他嘟噥道。顯然，惠勒認(rèn)為在皮膚上擦了檸檬汁，攝像頭就拍不著他了。畢竟，檸檬汁被用作隱形墨水，因此只要他不靠近熱源，他應(yīng)該是完全隱形的才對(duì)。

警方得出的結(jié)論是：惠勒腦子沒有問題也沒有嗑藥，只是徹底弄錯(cuò)了。

這個(gè)傳奇般的故事引起了康奈爾大學(xué)心理學(xué)家戴維·鄧寧的注意，他和研究生賈斯汀·克魯格一同對(duì)這一現(xiàn)象進(jìn)行研究。他們認(rèn)為，雖然幾乎每個(gè)人都認(rèn)為自己在社會(huì)和智力各個(gè)領(lǐng)域的能力表現(xiàn)不俗，但有些人明顯高估了自己的實(shí)際能力。這種“自信的幻覺”如今被稱作“鄧寧-克魯格效應(yīng)”，指的是自我評(píng)估時(shí)高估自己的認(rèn)知偏差。

為了在實(shí)驗(yàn)室研究這一現(xiàn)象，鄧寧和克魯格設(shè)計(jì)了一些巧妙的實(shí)驗(yàn)。在一項(xiàng)研究中，他們向本科生提了一系列關(guān)于語(yǔ)法、邏輯和笑話的問題，然后要求每個(gè)學(xué)生估計(jì)自己的總體成績(jī)，以及自己與其他學(xué)生的相對(duì)排名。有趣的是，那些在認(rèn)知測(cè)試中得分最低的學(xué)生總是高估自己——而且高估了不止一點(diǎn)點(diǎn)。得分排在后四分之一的學(xué)生估計(jì)自己的成績(jī)比其他三分之二的學(xué)生還要好！

這種“自信的幻覺”不只存在于課堂，而且滲透到了日常生活中。在一個(gè)后續(xù)的研究中，鄧寧和克魯格離開實(shí)驗(yàn)室去了一個(gè)靶場(chǎng)，在那里他們對(duì)射擊愛好者進(jìn)行了槍械安全知識(shí)的測(cè)試。與他們之前的研究結(jié)果類似，那些正確率最低的人遠(yuǎn)遠(yuǎn)高估了自己對(duì)槍支的認(rèn)識(shí)。除了事實(shí)性知識(shí)之外，鄧寧-克魯格效應(yīng)也可以在人們對(duì)其他各種個(gè)人能力的自我評(píng)估中觀察到。現(xiàn)如今，如果你在電視上看場(chǎng)選秀節(jié)目，你就會(huì)看到那些沒通過(guò)海選、被評(píng)委拒絕的選手臉上震驚的表情。雖然在我們看來(lái)這些人的表現(xiàn)近乎滑稽，但他們真的不知道自己在多大程度上是被優(yōu)越感的幻覺誤導(dǎo)了。

當(dāng)然，人們總是會(huì)高估自己的能力。一項(xiàng)研究發(fā)現(xiàn)，80%的司機(jī)認(rèn)為自己可以超過(guò)平均水平—— 這在統(tǒng)計(jì)學(xué)上是不可能的。人們?cè)谠u(píng)價(jià)自己的相對(duì)受歡迎程度和認(rèn)知能力時(shí)，研究結(jié)果也顯示出了類似的趨勢(shì)。問題是有些人能力不行，他們不但會(huì)得出錯(cuò)誤的結(jié)論，作出糟糕的選擇，而且他們也沒有能力去認(rèn)識(shí)到自己的錯(cuò)誤。對(duì)于自身的錯(cuò)誤，無(wú)能的人不會(huì)感到迷茫、困惑或是靜下心思考，他們總是堅(jiān)持自己是對(duì)的。查爾斯·達(dá)爾文在《人類的起源與性的選擇》（1871）中寫道：“無(wú)知比博學(xué)更容易帶來(lái)自信?！?p>

有趣的是，真正聰明的人也無(wú)法準(zhǔn)確地評(píng)估自己的能力。正如得分為D和F的學(xué)生會(huì)高估自身能力，得A的學(xué)生則會(huì)低估自身能力。鄧寧和克魯格在其經(jīng)典的研究中發(fā)現(xiàn)，認(rèn)知分?jǐn)?shù)排在前四分之一的優(yōu)秀學(xué)生低估了自己的相對(duì)能力。這些學(xué)生認(rèn)為，如果這些認(rèn)知測(cè)試對(duì)他們來(lái)說(shuō)很容易，那么對(duì)其他人而言肯定也一樣簡(jiǎn)單，甚至更簡(jiǎn)單。這一所謂的“冒名者綜合征”可以說(shuō)是反過(guò)來(lái)的鄧寧-克魯格效應(yīng)：優(yōu)秀的人無(wú)法認(rèn)識(shí)到自己的才能，認(rèn)為其他人同樣能干。不同的是，在得到適當(dāng)?shù)姆答伜?，有能力的人可以而且確實(shí)會(huì)在自我評(píng)估方面作出調(diào)整，而無(wú)能的人卻不能。

這里就是讓我們不會(huì)變成那個(gè)蠢蛋銀行劫匪的關(guān)鍵。有些時(shí)候我們嘗試會(huì)帶來(lái)有利結(jié)果的事情，但是其他時(shí)候——比如涂檸檬汁那個(gè)主意——我們的方法是有缺陷的、不理性的、笨拙的或者根本就是愚蠢透了的。訣竅在于不要被優(yōu)越感的幻覺所蒙蔽，并且學(xué)會(huì)準(zhǔn)確地重新評(píng)估我們的能力。畢竟，正如孔子所說(shuō)，“知之為知之，不知為不知，是知也”。

1. know-it-all： 自稱無(wú)所不知的人。

2. saga： 傳說(shuō)，長(zhǎng)篇故事，此處指事件。

3. quartile： 四分位數(shù)（的）。

4. myriad： 大量，無(wú)數(shù)。

5. audition： 試鏡，海選。

6. The Descent of Man： 《人類的起源》全名為《人類的起源與性的選擇》（The Descent of Man， and Selection in Relation to Sex），該書從各個(gè)方面以無(wú)可反駁的事實(shí)和論據(jù)闡述了人類是從猿類進(jìn)化而來(lái)的，同時(shí)詳細(xì)地論述了性選擇的問題；beget： 產(chǎn)生，引起。

7. imposter： 冒名頂替的人。“冒名者綜合征”又稱“負(fù)擔(dān)綜合征”，指優(yōu)秀的人內(nèi)心深處缺乏自信，覺得自己并不像別人想得那么好，優(yōu)秀的成就也是一時(shí)騙來(lái)的，不會(huì)長(zhǎng)久，自己只是冒牌貨，時(shí)時(shí)擔(dān)心會(huì)被拆穿，深受自卑感折磨。

8. witless： 愚蠢的。

閱讀感評(píng)

∷秋葉 評(píng)

我們常說(shuō)“無(wú)知者無(wú)畏”。此言出自孔子，他說(shuō)“君子有三畏，畏天命，畏大人，畏圣人之言”，而“小人”對(duì)于以上全然不知，因此全報(bào)以“不畏”與“輕蔑”，了無(wú)羈絆。達(dá)爾文（Charles Darwin， 1809—1882）也有類似的說(shuō)法：“Ignorance more frequently begets confidence than does knowledge.”（無(wú)知比博學(xué)更容易帶來(lái)自信）。我想，這位“進(jìn)化論”的偉大奠基人一定是認(rèn)為博學(xué)之人較為審慎多慮，而所知甚少者往往莽撞不羈。“無(wú)知者無(wú)畏”心態(tài)在前些年京味小說(shuō)家王朔接連大罵魯迅、老舍等經(jīng)典作家的事件中得到了淋漓盡致的展現(xiàn)。我們不能否認(rèn)“無(wú)知者無(wú)畏”心態(tài)有其突破陳規(guī)、不畏縮的優(yōu)勢(shì)，但其結(jié)局往往是災(zāi)難性的。一百多年前的“義和團(tuán)”運(yùn)動(dòng)，拳民們大多為山東、河北農(nóng)民，對(duì)于西洋除了仇恨外所知甚少，卻固執(zhí)地認(rèn)定洋人的膝蓋不能彎曲，戰(zhàn)力有限，而吹噓自己神功廣大，刀槍不入，不懼任何洋槍洋炮。他們作戰(zhàn)時(shí)采取人海戰(zhàn)術(shù)，確為勇往無(wú)畏，但結(jié)果是數(shù)萬(wàn)人數(shù)月圍攻區(qū)區(qū)幾百人防守的外國(guó)使館區(qū)而久攻不下，一朝面對(duì)八國(guó)聯(lián)軍即瞬間戰(zhàn)敗，北京城也慘遭生靈涂炭。

然而，我們?cè)谌粘Ｉ钪邪l(fā)現(xiàn)，完全“無(wú)知者”往往表現(xiàn)為膽怯、保守、舉步維艱，而往往是那些所謂的“半瓶子晃蕩”的淺嘗輒止者夸夸其談、自吹自擂，儼然以專家自居。西諺中也有類似的說(shuō)法：“A little knowledge （learning） is a dangerous thing.”（一知半解是一件危險(xiǎn)的事情）。該諺源自18世紀(jì)英國(guó)詩(shī)人蒲伯（Alexander Pope， 1688—1744）的名詩(shī)《論批評(píng)》（“An Essay on Criticism”， 1709），首節(jié)即妙語(yǔ)連珠：“一知半解是一件危險(xiǎn)的事情/派利亞泉水（Pierian spring）要深吸，否則別飲/淺淺喝幾口使大腦不清，/大量暢飲反會(huì)使我們清醒。”這些詩(shī)行針對(duì)的似乎就是本文中的那位竊賊，以為銀行監(jiān)控對(duì)于他的“檸檬水蒙面”無(wú)能為力，其自作聰明的結(jié)局當(dāng)然是當(dāng)天就束手就擒！

心理學(xué)上的鄧寧-克魯格效應(yīng)認(rèn)定“高估自我”乃人之常情，這認(rèn)知上的偏差恰如人性的弱點(diǎn)，不可避免。原文所舉例證皆來(lái)自現(xiàn)實(shí)，諸如班上成績(jī)居末的學(xué)生自以為能力在中等之上；那些槍支愛好者雖答不上幾個(gè)有關(guān)武器安全方面的問題，卻自認(rèn)為有著豐富的槍械知識(shí)；大多數(shù)司機(jī)都認(rèn)為自己車技出眾；那些連電視海選都上不了榜的業(yè)余歌手，一旦被裁判為出局，第一反應(yīng)不是自己才藝能力問題，而是裁判的不公！這些虛幻而盲目的自信的例子確實(shí)存在，但筆者認(rèn)為還有兩類人的自我認(rèn)知偏差更具隱蔽性與欺騙性。一種可稱之為假行家（charlatan），不管談什么都以權(quán)威自居，對(duì)于一些文獻(xiàn)來(lái)源與調(diào)查數(shù)據(jù)說(shuō)一不二，盛氣凌人，儼然只有他/她才掌握這絕對(duì)真理。這種人并非完全無(wú)知，但往往能力有限，只是表演的功夫了得，用狂妄來(lái)掩蓋自己學(xué)識(shí)淺薄。據(jù)說(shuō)，英國(guó)哲學(xué)家培根（Francis Bacon）早就有言：“That a little knowledge is apt to puff up， and make men giddy， but a greater share of it will set them right， and bring them to low and humble thoughts of themselves.”（知識(shí)淺薄讓人內(nèi)心膨脹，頭腦發(fā)昏。深入下去將讓他們擺正位置，有自知之明）?？磥?lái)，人之謙虛是下苦功的結(jié)果！英文中有個(gè)現(xiàn)成詞“A Know-Nothing Know-It-All”，用來(lái)形容這種“半瓶水”顯擺、“缺乏教養(yǎng)”之流再合適不過(guò)。另一種人倒是有些自知之明，并不自詡為權(quán)威，而是坦言自己為“草根”，但他們抓住一點(diǎn)不及其余地宣稱專家權(quán)威的不可靠，甚至從根本上否認(rèn)他們的存在，要大家認(rèn)同“只有草根才值得崇尚，只有草根的意見才是真正可靠的”等觀點(diǎn)。這貌似在高舉自由主義、平等主義大旗，其實(shí)是在不切實(shí)際地高估“草根”自我的能力與作用。具有反諷意味的是，他們?cè)谡撌鲞@些觀點(diǎn)時(shí)，往往自覺不自覺地會(huì)抬出一些理論家來(lái)為自己撐腰。這種人貌似謙虛，實(shí)則傲慢，因?yàn)樗麄儼炎约旱挠^點(diǎn)強(qiáng)加于人，而且出爾反爾。當(dāng)然，專家與權(quán)威均可質(zhì)疑，這是學(xué)術(shù)常識(shí)，也是我們應(yīng)持的態(tài)度，但不宜全盤否定，更不能強(qiáng)行予以“掃地出門”。總之，不管是無(wú)知者還是“半瓶水”，還是要多一點(diǎn)謙遜與自知之明，少一點(diǎn)固執(zhí)與自以為是?！妒ソ?jīng)》的《羅馬書》上有一句格言說(shuō)得好：“Professing themselves to be wise， they became fools.”（Romans 1：22 自認(rèn)聰明，實(shí)為傻子）。