Why Ebola is scarier than it should be

In 2012, more than 33,000 Americans died on the highways. In some recent years, the flu has killed tens of thousands. Alcohol is associated with some 70,000 deaths annually, weight problems with more than 300,000, and smoking with over 400,000. Even a single one of these preventable deaths is a tragedy. But the risks they pose do not greatly trouble most people in their daily lives. What's worrying many people much more these days is the far lower risk, at least in the U.S. and Europe, of contracting Ebola. What, then, can public officials do to stem the public anxiety? The problem is that Ebola fear presents a delicate challenge -- one that official assurances might just make worse, at least if they breed distrust. In thinking about risks, people use something behavioral scientists call the “availability heuristic”: They believe that something is more probable if they can readily think of examples -- as they can when something is in the news. This explains why earthquake insurance rises sharply after there's just been an earthquake, but declines as vivid memories recede. The availability heuristic also helps explain why, in the three months after the Sept. 11 attacks, many people chose to drive rather than fly. And because driving is more dangerous, more than 300 Americans lost their lives as a result of that choice -- a higher number than the total passenger deaths on the four fatal flights. Behavioral science has uncovered a related point: When a risk triggers strong emotions, people often focus on terrible outcomes, and do not much consider the (low) probability that they will occur. Terrorists try to exploit this phenomenon by making people think they cannot be safe anywhere. An infectious disease can lead to overreaction for precisely the same reason. Research on risk perception, undertaken by psychologist Paul Slovic and his colleagues, has also found that people especially fear risks that are new, unfamiliar, involuntarily incurred, potentially catastrophic and apparently uncontrollable. That's not so surprising, but the consequence is that people can be far more afraid of statistically small risks (those associated with pesticides, for instance) than of statistically larger ones (those associated with smoking or texting while driving). Some dangers trigger genuine dread, and people will take extreme measures to avoid them, whether or not it makes a lot of sense to do so. Dread is also often subject to a harmful process of “social amplification” -- the ripple effects caused by sustained media attention -- thus producing burdens and costs that go far beyond the risks themselves. A few highly publicized incidents can move people to be frightened quite beyond what reality warrants. With Ebola, every one of these fear amplifiers is in play. There is also something distinctly primal about this particular threat, something that taps into nightmares that linger in the human psyche, and that have become familiar from popular movies and literature. (Are we in the midst of World War Z?) For those who seek to calm the public, it is necessary, of course, to ensure that the appropriate precautions are taken. It might even make sense to take measures beyond those warranted on strictly scientific grounds, in order to help people feel safer, and in full recognition of the serious social consequences if and when further cases of Ebola arise. But assurances and precautions carry a risk of their own: that they will aggravate, rather than diminish, public fear. Public officials often do best when they emphasize that a seemingly new threat is a kind of problem that we have been perfectly able to handle before. The U.S. has had plenty of experience with infectious diseases -- including flu, pneumonia, salmonella, measles and hepatitis -- many of which are far more easily spread than Ebola. Yet Americans have figured out how to minimize and live with the risks. Right now, the very word Ebola is conjuring all sorts of terrible scenarios, and it demands official attention. But it does not belong in a category all its own. In West Africa, Ebola's toll is large and growing at a horrifying rate. In the U.S. and Europe, the only thing most people have to fear is fear itself. To contact the writer of this article: Cass R. Sunstein at csunstei@law.harvard.edu.