Shortly after the University of Washington announced that the school’s fourth suspected case of the new coronavirus had turned out negative, two professors, one of public policy and the other of public health, held a small dinner for students and faculty members.

华盛顿大学宣布该校第四例新型冠状病毒疑似病例排除，两位教授——一位公共政策教授和一位公共卫生教授——随即邀请学生和教员们参加了一场小型晚宴。

Like everywhere else on campus, and in much of the world, the coronavirus was all anybody could talk about.

和校内其他地方乃至世界各地一样，在宴会上，冠状病毒成了唯一的话题。

But one of the attendees, a public health student, had had enough. Exasperated, she rattled off a set of statistics.

但是，其中一位参与者，一名公共卫生学生，表示她受够了。盛怒之下，她一口气说出一组统计数据。

The virus had killed about 1,100 worldwide and infected around a dozen in the United States. Alarming, but a much more common illness, influenza, kills about 400,000 people every year, including 34,200 Americans last flu season and 61,099 the year before.

该病毒已经在全球范围内导致1100人死亡，在美国大约感染了十几人。令人担忧但要常见许多的流感每年造成约40万人死亡，其中包括上个流感季的死亡的34200美国人和之前一年流感季死亡的61099个美国人。

There remains deep uncertainty about the new coronavirus’ mortality rate, with the high-end estimate that it is up to 20 times that of the flu, but some estimates go as low as 0.16 percent for those affected outside of China’s overwhelmed Hubei province. About on par with the flu.

新型冠状病毒的死亡率目前还很难说，根据估计，其最高值可达流感的20倍，但如果除去被疫情冲垮的中国湖北省，某些估计值低至0.16％。与流感差不多。

Wasn’t there something strange, the student asked, about the extreme disparity in public reactions?

学生问，公众反应存在如此极端的反差，不觉得奇怪吗？

Ann Bostrom, the dinner’s public policy co-host, laughed when she recounted the evening. The student was right about the viruses, but not about people, said Dr. Bostrom, who is an expert on the psychology of how humans evaluate risk.

晚宴的合办人、公共政策教授安·博斯特罗姆(Ann Bostrom)在回述当晚的情形时笑了起来。作为一名人类风险评估心理学方面的专家，博斯特罗姆说，这位学生对病毒的理解是正确的，但对人的理解却不正确。

While the metrics of public health might put the flu alongside or even ahead of the new coronavirus for sheer deadliness, she said, the mind has its own ways of measuring danger. And the new coronavirus disease, named COVID-19 hits nearly every cognitive trigger we have.

她说，公共卫生指标可能会根据绝对的致死率将流感与新型冠状病毒并列，甚至排在新型冠状病毒前面，但人自有一套衡量危险的方法。而被命名为COVID-19的新型冠状病毒病几乎击中了我们所有触发认知的因素。

That explains the global wave of anxiety.

这解释了全球范围内的焦虑情绪。

Of course, it is far from irrational to feel some fear about the coronavirus outbreak tearing through China and beyond.

当然，对席卷中国乃至其他地方的冠状病毒疫情暴发感到恐惧，绝非不理智的表现。

But there is a lesson, psychologists and public health experts say, in the near-terror that the virus induces, even as serious threats like the flu receive little more than a shrug. It illustrates the unconscious biases in how human beings think about risk, as well as the impulses that often guide our responses — sometimes with serious consequences.

但是心理学家和公共卫生专家说，从人们对这种病毒近乎恐慌、而不把流感这种严重的威胁当回事的现象中，我们可以得到一条教训。它说明了人们在风险评估中的无意识偏见，以及常常以冲动来引导我们的回应方式——有时会导致严重的后果。

Experts used to believe that people gauged risk like actuaries, parsing out cost-benefit analyses every time a merging car came too close or local crime rates spiked. But a wave of psychological experiments in the 1980s upended this thinking.

专家曾经认为，人们会像精算师那样评估风险，当正在变道的汽车离得太近，或当本地犯罪率激增的时候，就会进行成本效益分析。然而1980年代的一系列心理学实验颠覆了这种想法。

Researchers found that people use a set of mental shortcuts for measuring danger. And they tend to do it unconsciously, meaning that instinct can play a much larger role than they realize.

研究人员发现，人们使用一系列思维捷径来衡量危险。这往往是无意识的，意味着本能发挥的作用可能比他们意识到的要大得多。

The world is full of risks, big and small. Ideally, these shortcuts help people figure out which ones to worry about and which to disregard. But they can be imperfect.

世界充满着大大小小的风险。理想情况下，这些思维捷径可以帮助人们找出哪些问题值得关注，哪些需要忽略。但是它们可能并不完美。

The coronavirus may be a case in point.

冠状病毒也许就是这样一个例子。

“This hits all the hot buttons that lead to heightened risk perception,” said Paul Slovic, a University of Oregon psychologist who helped pioneer modern risk psychology.

现代风险心理学的先锋、俄勒冈大学的心理学家保罗·斯洛维奇(Paul Slovic)说：“导致人们提高风险感知的按钮，这一次全部触击到了。”

When you encounter a potential risk, your brain does a quick search for past experiences with it. If it can easily pull up multiple alarming memories, then your brain concludes the danger is high. But it often fails to assess whether those memories are truly representative.

当你遇到潜在风险时，你的大脑会将它在过去的经验中进行一次快速搜索。如果它可以轻易地唤起多个令人担忧的记忆，那么你的大脑就会作出危险很高的结论。但是，它常常无法评估这些记忆是否真正具有代表性。

A classic example is airplane crashes.

一个典型的例子是坠机。

If two happen in quick succession, flying suddenly feels scarier — even if your conscious mind knows that those crashes are a statistical aberration with little bearing on the safety of your next flight. But if you then take a few flights and nothing goes wrong, your brain will most likely start telling you again that flying is safe.

如果两次坠机事件连续发生，坐飞机突然变成了可怕的事情——即使你的意识头脑知道那些坠机事件是极小的几率，对你下一次的飞行几乎没有安全影响。但是，如果你随后坐了几次飞机都没有任何问题，那么你的大脑很可能会开始告诉你坐飞机是安全的。

When it comes to the coronavirus, Dr. Slovic said, it’s as if people are experiencing one report after another of planes crashing.

斯洛维奇说，涉及冠状病毒时，好像人们正在经历一个又一个飞机坠毁的报告。

“We’re hearing about the fatalities,” he said. “We’re not hearing about the 98 or so percent of people who are recovering from it and may have had mild cases.”

“我们听到的消息是死亡人数，”他说。“而不是98％左右的人正在从中康复，并且可能只患了轻症。”

That tendency can cut in both directions, leading not to undue alarm but undue complacency. Though flu kills tens of thousands of Americans every year, most peoples’ experiences with it are relatively mundane.

这种趋势也可以走向另一个极端，除了不必要的担忧外也会导致不必要的自大。尽管流感每年导致成千上万的美国人死亡，但大多数流感患者的感受平淡无奇。

Being told how dangerous flu is does little to change this, studies find. The brain’s risk assessment approach simply overwhelms rational calculation — a source of endless consternation to health officials trying to raise flu vaccination rates.

研究发现，告知流感有多么危险并不会改变这个情形。大脑的风险评估法直接盖过了理性计算——这让试图提高流感疫苗接种率的卫生官员感到无尽惊愕。

“We’re conditioned by our experiences,” Dr. Slovic said. “But experience can mislead us to be too comfortable with things.”

“我们受到经验的条件反射，”斯洛维奇说。“但是经验会误导我们对事物过于习惯。”

The coronavirus also taps into other psychological shortcuts for assessing risk.

人们对冠状病毒风险的评估还涉及其他心理捷径。

One involves novelty: We are conditioned to focus heavily on new threats, looking for any cause for alarm. This can lead us to obsess over the scariest reports and worst-case scenarios, making the danger seem bigger still.

其中一个涉及新颖性：我们习惯于将精力集中在新的威胁上，寻找任何引发担忧的原因。这可能导致我们沉迷于最糟糕的消息和最坏的情况，使危险看上去更大。

Maybe the most powerful shortcut of all is emotion.

也许最强大的捷径是情绪。

Assessing the danger posed by the coronavirus is extraordinarily difficult; even scientists are unsure. But our brains act as if they have an easier way: They translate gut emotional reactions into what, we believe are reasoned conclusions, even if hard data tells us otherwise.

评估冠状病毒带构成的危险极其困难；即使是科学家也不确定。但是，我们的大脑似乎用一种更容易的方式：将情绪直觉反应转化为我们自以为合理的结论，即使它与坚实的数据相悖。

“The world in our heads is not a precise replica of reality,” Daniel Kahneman, a Nobel Prize-winning economist, wrote in a 2011 book. “Our expectations about the frequency of events are distorted by the prevalence and emotional intensity of the messages to which we are exposed.”

“我们头脑中的世界并非现实的精确复制品，”诺贝尔经济学奖获得者丹尼尔·卡尼曼(Daniel Kahneman)在他2011年的书中写道。“我们面前的信息的普遍性和情感强度，会左右我们对事件发生频率的判断。”

In extreme cases, this can lead to a “crowding-out effect,” Dr. Bostrom said, as our emotional impulses overwhelm our cognitive faculties. The coronavirus hits a number of those triggers, often quite hard.

博斯特罗姆说，在极端情况下，这可能导致“挤出效应”(crowding-out effect)，因为我们的情绪冲动压倒了我们的认知能力。冠状病毒触击到了这些诱发因素，力度通常很强。

One is dread.

其中一个是恐惧。

If a risk seems especially painful or disturbing, people tend to raise their estimate of how likely it is to happen to them. Reports on the coronavirus often feature upsetting imagery: unhygienic food markets, city-scale lockdowns and overcrowded hospitals.

如果一个风险看起来特别痛苦或令人不安，人们往往会提高这种风险发生在自己身上的几率的估计。关于冠状病毒的报道通常带有令人不安的图像：不卫生的食品市场，整座城市的封锁和人满为患的医院。

Another trigger is a threat that is not fully understood. The less known it is, the more people may fear it, and overestimate its threat.

另一个触发因素是人们尚未完全了解病毒的威胁。它越不为人所知，就会有越多的人担心它，并高估它的威胁。

Threats that feel out of control, like a runaway disease outbreak, prompt a similar response, leading people to seek ways to reimpose control, for instance by hoarding supplies.

令人感到失控的威胁，例如失控的疾病暴发，会引发类似的反应，导致人们寻求重新实施控制，例如囤积物资。

Risks that we take on voluntarily, or that at least feel voluntary, are often seen as less dangerous than they really are. One study found that the danger people increases by a factor of one thousand if they it as a choice.

我们自愿承担的风险或至少感到自愿的风险，通常被认为是低于实际风险的。一项研究发现，如果人们把危险视为一个选择，那么危险会增加一千倍。

If that number sounds high, consider that driving, a danger most take on voluntarily, kills over 40,000 Americans every year. But terrorism, a threat imposed on us, kills fewer than 100.

There are countless rational reasons that terrorism provokes a sharper response than traffic deaths. The same goes for a fast-spreading and little-understood outbreak versus the familiar flu.

有无数合理的原因使恐怖主义比交通死亡更能引起人们的强烈反响。同样，快速传播且人们知之甚少的病毒暴发相对于熟悉的流感也是如此。

And that is exactly the point, psychologists say.

心理学家说，这正是重点。

“All of these things play on our feelings,” Dr. Slovic said. “And that’s the representation of threat for us. Not the statistics of risk, but the feelings of risk.”

“所有这些事情都影响着我们的感觉，”斯洛维奇说。“这就是我们经受威胁的表现。不是风险的统计，而是风险的感觉。”

All those emotions can have real consequences.

所有这些情绪都可以产生现实后果。

Consider the response to the partial meltdown of the nuclear plant at Three Mile Island, in Pennsylvania, in 1979. Though the incident caused no deaths, it led to public demand to turn from nuclear power to fossil fuels whose impact on air quality, alone, is thought to cause thousands of premature deaths every year.

参考人们对1979年宾夕法尼亚州三英里岛核电站部分熔毁的反应。虽然该事件没有造成死亡，但它导致公众要求从核电转向化石燃料，而后者被认为单单是对空气质量的影响就导致了每年超过数千人过早死亡。

That calculus confounded old-school economists, who saw it as irrational. One leading nuclear power expert called it “insane.”

这种计算使老派经济学家感到困惑，他们认为这是非理性的。一位杰出的核电专家称其为“疯狂”。

But it also helped give rise to new psychological models for how people measure risk.

但这也有助于建立人们如何衡量风险的新心理模型。

“Our feelings don’t do arithmetic very well,” Dr. Slovic said.

斯洛维奇说：“我们的感觉并不太会做算术。”

That can be especially true when judging low-probability, high-risk threats like nuclear war, terrorism — or dying from the coronavirus or the flu.

在判断低概率、高风险威胁，例如核战争、恐怖主义，或死于冠状病毒或流感时，尤其如此。

Our minds tend to either “round down” the probability to “basically zero” and we underreact, Dr. Slovic said. Or we focus on the worst-case outcome, he said, which “gives us a strong feeling, so we overreact.”

斯洛维奇说，我们的头脑要不就是倾向于将概率“基本上舍入为零”，继而反应不够，要不就是专注于最糟糕的结果，这“让我们产生强烈的感觉，于是反应过度”。