想象一下：在NBA總決賽上，克里夫蘭騎士隊(duì)的勒布朗·詹姆斯剛剛進(jìn)了一個(gè)跳投。然后他又進(jìn)了一個(gè)。又一個(gè)。

三投三中，他手感真棒，接下來(lái)這球也跑不了，對(duì)吧？

大多數(shù)人都會(huì)毫不猶豫地回答：“對(duì)”。但人們的判斷其實(shí)和小皇帝的技術(shù)沒(méi)什么關(guān)系，更多來(lái)自大腦的猜測(cè)?？此埔粋€(gè)簡(jiǎn)單的預(yù)期，其實(shí)是長(zhǎng)期進(jìn)化的結(jié)果。不過(guò)這種預(yù)感最大的問(wèn)題就是準(zhǔn)確度不高。從統(tǒng)計(jì)數(shù)據(jù)看，勒布朗投進(jìn)的可能性并不比打到籃筐彈出去的可能性大多少，跟之前是否連續(xù)進(jìn)球沒(méi)什么關(guān)系。

這種不假思索就得出結(jié)論的現(xiàn)象叫做“近因效應(yīng)”，深藏在我們的情感脈絡(luò)中。杜克大學(xué)行為經(jīng)濟(jì)學(xué)教授、《可預(yù)測(cè)的非理性》（Predictably Irrational）等書作者（也是最早提出上述投籃類比的人）丹·艾瑞里說(shuō)：“這種效應(yīng)很有趣。人們總是看最新的證據(jù)，過(guò)于當(dāng)真，而且預(yù)計(jì)后面會(huì)發(fā)生同樣的事?！?

“近因效應(yīng)”在進(jìn)化上有優(yōu)勢(shì)?；叵肴祟愖嫦仍诜侵薮蟛菰系纳睿喝绻硞€(gè)水源點(diǎn)連續(xù)幾天都有角馬出沒(méi)，很有可能人們會(huì)繼續(xù)去那打獵。如今我們坐在計(jì)算機(jī)前不用再外出打獵，卻仍然本能地在最近發(fā)生的事件中尋找規(guī)律，較久遠(yuǎn)的記憶對(duì)我們行為的影響則較小。

當(dāng)然了，問(wèn)題在于角馬并不會(huì)總在同一地點(diǎn)出現(xiàn)。所以近因效應(yīng)對(duì)投資者來(lái)說(shuō)很特別危險(xiǎn)，一個(gè)不留神就會(huì)變成為人們大腦中錯(cuò)估投資方向的罪魁禍?zhǔn)?。理智上，我們都知道本世紀(jì)已經(jīng)出現(xiàn)了兩次大熊市，分別是在2000-2002年和2007-2009年。然而今年3月，現(xiàn)代史上持續(xù)時(shí)間第二長(zhǎng)的牛市即將進(jìn)入第八個(gè)年頭，近因效應(yīng)可能會(huì)給我們一種虛假的安全感，特別是看到過(guò)去三、四年非常高的回報(bào)以后。艾瑞里指出：“想想資產(chǎn)泡沫形成的過(guò)程就會(huì)發(fā)現(xiàn)，情況往往如此。市場(chǎng)上漲再上漲，我們就開(kāi)始認(rèn)為會(huì)一直漲下去?！?

市場(chǎng)專業(yè)人士也難免受這種思維方式影響。2008年初，全球經(jīng)濟(jì)乍現(xiàn)疲軟之勢(shì)。但在連續(xù)五年實(shí)現(xiàn)正回報(bào)以后，股票分析師的信心也升至歷史高點(diǎn)。研究機(jī)構(gòu)Bespoke Investment Group最近的研究顯示，當(dāng)時(shí)華爾街一致認(rèn)為市場(chǎng)還能上漲11.1%。大家應(yīng)該想到了，分析師的預(yù)測(cè)主要依據(jù)也是近期行情。我們也都知道接下來(lái)發(fā)生了什么——經(jīng)濟(jì)斷崖式下跌，當(dāng)年標(biāo)普500指數(shù)跌去了38.5%。

近因效應(yīng)還有助于解釋貪婪或恐慌行情中散戶的行為。投資研究公司TrimTabs Investment Research首席執(zhí)行官大衛(wèi)?桑茨奇指出，資產(chǎn)流入經(jīng)常出現(xiàn)在股市就要見(jiàn)頂時(shí)，流出則經(jīng)常出現(xiàn)在市場(chǎng)底部，正好跟投資者應(yīng)該采取的操作相反。最近的情況就讓人感覺(jué)不妙——基金研究機(jī)構(gòu)晨星的數(shù)據(jù)顯示，去年12月流入美國(guó)股票共同基金的資金達(dá)278億美元，是2000年4月科技股臨近崩盤以來(lái)月度流入最高記錄。

行為經(jīng)濟(jì)學(xué)家、加州大學(xué)洛杉磯分校教授什洛莫·本納茨認(rèn)為，快要退休的投資者特別容易受近因效應(yīng)的影響，然而臨近退休正是最虧不起大把錢的時(shí)候。這是衰老應(yīng)對(duì)機(jī)制的一部分——如果一生中總是接連不順，感到無(wú)能為力，人們就會(huì)失去生活的勇氣。但往往牛市接近尾聲時(shí)投資者的決策最容易過(guò)度樂(lè)觀，承擔(dān)巨大的風(fēng)險(xiǎn)。

對(duì)于未來(lái)，估計(jì)專家也算不準(zhǔn)熊市什么時(shí)候來(lái)——話說(shuō)回來(lái)，確認(rèn)沒(méi)人說(shuō)對(duì)過(guò)。那么，我們?cè)鯓硬拍艿钟⑾魅踅蛐?yīng)的影響，不讓過(guò)于樂(lè)觀（同樣的，過(guò)于悲觀）的傾向?qū)Q策產(chǎn)生不利影響呢？初學(xué)者可以讓證券投資進(jìn)入“自動(dòng)駕駛”模式，剔除情緒波動(dòng)因素。目標(biāo)日期基金或許是個(gè)選擇，這種基金會(huì)自動(dòng)調(diào)整投資配置，隨著持有人年齡的增長(zhǎng)降低投資風(fēng)險(xiǎn)。Betterment和Wealthfront等智能投顧機(jī)構(gòu)也能幫上，只要提前設(shè)置好就能在某類資產(chǎn)的價(jià)格達(dá)到不正常水平時(shí)自動(dòng)讓證券投資重新回歸平衡。多倫多大學(xué)行為經(jīng)濟(jì)學(xué)家麗莎·克雷默說(shuō)：“我熱愛(ài)所有阻止人們沖動(dòng)決定的投資方法。”

歷史數(shù)據(jù)也是決策時(shí)值得考慮的因素。摩根大通資產(chǎn)管理指出，牛市平均長(zhǎng)度為54個(gè)月，比截至今年1月的奧巴馬-特朗普行情短41個(gè)月。標(biāo)普500指數(shù)的長(zhǎng)期平均市盈率呢？只有15倍，而目前的市盈率已經(jīng)超過(guò)25倍。這些長(zhǎng)期指標(biāo)表明，要維持目前的估值和市場(chǎng)的良好表現(xiàn)并不容易。

正因?yàn)槿绱?，如果市?chǎng)下跌，一定要確保所有操作都是根據(jù)長(zhǎng)期計(jì)劃，而不是CNBC最新報(bào)道傳播的情緒。主要指數(shù)不斷破記錄的時(shí)候就是投資者進(jìn)行調(diào)整的良機(jī)。如果總投資中股票的比重已經(jīng)從60%的目標(biāo)值一路上升，已經(jīng)達(dá)到比方說(shuō)75%，可以賣掉一部分股票鎖定利潤(rùn)，把資金投入市場(chǎng)滑坡時(shí)較為堅(jiān)挺的資產(chǎn)，比如投資級(jí)債券。年紀(jì)大一些的投資者可以把資金轉(zhuǎn)移到風(fēng)險(xiǎn)更小的資產(chǎn)中，比如現(xiàn)金或年金。

Fuller & Thaler Asset Management研究主管拉斐·吉?dú)W凡納佐認(rèn)為：“投資時(shí)千萬(wàn)不能跟著情緒走，就像希臘神話中駕船穿過(guò)塞壬海妖歌聲的奧德修斯一樣。用蠟堵住耳朵，把自己綁在桅桿上，否則只能眼睜睜跟著市場(chǎng)一瀉千里。”

怎樣克服既有思維定勢(shì)

包括“近因效應(yīng)”在內(nèi)，根深蒂固的思維習(xí)慣可能影響投資者的決策，導(dǎo)致投資蒙受損失。以下三種方法可以盡量克服。

價(jià)格高時(shí)要當(dāng)心

如果價(jià)格/市盈率高得離譜，經(jīng)常意味著股票上漲時(shí)間有些過(guò)長(zhǎng)。目前股票價(jià)格已經(jīng)遠(yuǎn)高于平均水平，或許是個(gè)賣出大漲股落袋為安的好機(jī)會(huì)。

為了退休安全操作

退休前后幾年是投資損失對(duì)長(zhǎng)期計(jì)劃影響最嚴(yán)重的時(shí)候。處在這個(gè)階段的人應(yīng)該考慮把資金更多地配置在現(xiàn)金和債券上，不管感覺(jué)市場(chǎng)有多牛。

依靠“自動(dòng)駕駛”

在興奮狀態(tài)下，阻止沖動(dòng)型買賣的工具會(huì)很有用。目標(biāo)日期基金、“智能投顧”以及年金都可以幫助投資者避免在牛市中冒太多風(fēng)險(xiǎn)，或者在熊市中恐慌拋售。

作者：Chris Taylor

譯者：Charlie

審校：夏林

Picture this: It’s the NBA Finals, and LeBron James has just drained a jump shot for the Cleveland Cavaliers. Then he hits another. And another.

He’s on a hot streak: three in a row. He’s going to hit the next one, right?

Most people would unhesitatingly reply, “Yes.” That assumption doesn’t say as much about King James’s skills as it does about the inner workings of your own brain. Indeed, a whole lot of evolutionary history is packed into that projection. But here’s the thing about that hunch: It’s off the mark. Statistically, LeBron isn’t significantly more likely to make the shot than he is to clang it off the back rim—streak or no streak.

This leaping-to-conclusions phenomenon is called “recency bias,” and it’s deep in our emotional wiring. “It’s an interesting effect,” says Dan Ariely, a professor of behavioral economics at Duke University and the author of books including Predictably Irrational (and the originator of the hoops analogy). “We look at the most recent evidence, take it too seriously, and expect that things will continue in that way.”

There’s an evolutionary advantage to this. Think back to the origins of humanity somewhere on the African savannas: If the wildebeests have shown up at the same watering hole a few days in a row, odds are we’re going to hunt at that same spot the next day. Nowadays, though we’re hunched at computers instead of hunting game, we still instinctively seek patterns in the events that have happened most recently, while memories of older occurrences have less influence over our behavior.

The problem, of course, is that the wildebeests don’t always come back. And that makes recency bias particularly dangerous for investors: Unchecked, it’s your brain’s very own portfolio killer. Intellectually, we know that the market already saw two brutal bear markets this century—in 2000–02 and 2007–09. But as we approach the eighth birthday in March of the second-?longest bull market in modern times, recency bias can lull us into a false sense of security, especially given the very good returns of the past three or four years. “If you think about the creation of asset bubbles, that’s always what happens,” Ariely says. “Things go up and up and up, and we start thinking it has to always go up.”

Market professionals are hardly immune to this trend. At the beginning of 2008, trouble signs were emerging in the global economy. But after five straight years of positive returns, sentiment among equity analysts neared an all-time high, with the Wall Street consensus calling for an 11.1% gain, according to a recent study by Bespoke Investment Group. Their calls were based in part on—you guessed it—analysis of the recent past. We all know what happened next: The economy went off a cliff, and the S&P 500 fell 38.5% that year.

Recency bias also helps explain retail investor behavior during times of greed or panic. Assets often flow into stocks near market tops and exit at the bottom—exactly the opposite of what investors should be doing, says David Santschi, CEO of TrimTabs Investment Research. Recent signs here aren’t encouraging: Net inflows for U.S. stock mutual funds hit $27.8 billion in December, according to fund research shop Morningstar—the highest monthly total since April 2000, at the dawn of the tech-stock crash.

Investors can be particularly susceptible to recency bias as they get closer to retirement—?exactly the time when they can least afford big losses. That’s part of the mechanism of coping with aging, according to Shlomo Benartzi, a behavioral economist and UCLA professor. If we felt constantly hamstrung by the bad things that have happened to us over the course of our lives, none of us would get out of bed. But those rose-tinted glasses can cloud investing decisions, leading savers to assume too much risk at the tail end of a bull market.

Looking ahead, few experts are predicting the imminent arrival of a bear market—then again, few ever do. So how can you combat and counteract your own recency bias and resist letting excessive optimism (or pessimism, for that matter) hurt your decision-making? For starters, you could put your portfolio on autopilot, taking your mood swings out of the equation. That might mean vehicles like target-date funds, which shift investment allocations automatically to make them less risky as the account holder ages. Also helpful: robo-advisers such as Betterment and Wealthfront, which can be set up to rebalance your portfolio automatically when the prices of one asset class get out of whack. “I’m a big fan of any investing approach that removes us from impulse-based decisions,” says Lisa Kramer, a behavioral economist at the University of Toronto.

It’s also worth keeping historical data in your decision-making arsenal. The average bull-market length is 54 months, according to J.P. Morgan Asset Management—41 months shorter than the Obama-Trump bull run, through January. And the S&P 500 long-term average price/earnings ratio? It’s just 15, compared with more than 25 today. That kind of wider context signals that today’s valuations and recent good times won’t be easy to sustain.

All the more reason to make sure that, if and when the market does turn, any moves you make will be driven by a long-term plan rather than the emotions generated by the last thing you heard on CNBC. With major indexes setting records, it’s a good time for investors to rebalance: If the equities portion of your portfolio has ballooned from your 60% target to 75%, say, take some profits off the table and use them to buy asset classes that are hardier during downturns, like investment-grade bonds. Older investors may want to move that money into assets that are even less risky, like cash or annuities.

“In investing you have to deny your emotions, like Odysseus sailing by the sirens in Greek mythology,” says Raife Giovin?azzo, research director at Fuller & Thaler Asset Management. “Put wax in your ears or tie yourself to the mast—otherwise, you’re going to drown along the cliffs.”

How to Beat Your Biases

Deep-rooted mental habits, including “recency bias,” can throw off investors’ decision-making and hurt their portfolios. Here are three ways to keep those habits in check.

Watch out for high prices

Unusually high price/earnings valuations are often a sign that the party for stocks has gone on a little too long. With stocks trading well above their averages, now may be a good time to sell big winners and put the profits aside.

Play it safe for retirement

The years immediately before and after retirement are when losses can hurt an investor’s long-term plans the most. Savers in that life stage should consider putting more money in cash and bonds—no matter how bullish they feel.

Rely on an autopilot

When emotions run high, it helps to have tools that discourage buying or selling on impulse. Target-date funds, “robo-advisers,” and annuities can help investors avoid taking excessive risks in good times or panic selling in bad.