The next time you're faced with the decision to evacuate during a forecasted hurricane, it may be a smart move not to investigate how many times previous hurricanes in the area failed to cause damage.

An article in the latest issue of Risk Analysis [1] finds that people who have knowledge of near-miss experiences associated with dangerous events perceive risk differently from those with no knowledge of near-misses.

"Our research...shows how people who have experienced a similar situation but escape damage because of chance will make decisions consistent with a perception that the situation is less risky than those without the past experience," write researchers Robin L. Dillon and Catherine H. Tinsley of Georgetown University and Matthew Cronin of George Mason University.

The authors explain that a near-miss is when people escape a disaster because of luck, such as the failure of underwear bomber Umar Farouk Abdulmutallab to detonate his explosive device on Flight 253 bound for Detroit on Christmas 2009, giving passengers the time to subdue him. Or when winds out of the northwest arise out of nowhere to push a wildfire away from a residential area in California.

"People appear to mistake such good fortune as an indicator of resiliency," the authors note. But it's not; it's just luck.

To test whether knowledge of past misses leads to overconfident risk perceptions, the researchers set up two experiments involving hurricane scenarios.

In the first study, the researchers asked a mixed group of approximately 100 MBA students and  "risk-interested participants" whether they wanted to buy flood insurance for a home they just purchased in a hurricane-prone area. The participants were then broken up into three groups: those given no information on past near-misses, those told a near-miss occurred last year, and finally those told near-misses had occurred for the past three seasons.

Regardless of whether they were students or participants with risk expertise, an overwhelming majority bought flood insurance when they had no information on past near-misses. But once participants learned of prior near-misses, their desire to buy flood insurance dropped, although professionals with some risk expertise needed more misses before they decided to forgo flood insurance.

Then in the second study, the researchers asked 258 undergraduates whether they would evacuate after receiving information that a hurricane could hit their area within 36 hours. They were then divided into two groups: those told no previous damage information was available and those told they had lived through three previous storms that did not damage their or their neighbor's properties. Researchers complicated their decision by giving different members of each group four different probabilities that the hurricane would strike tied to increasing evacuation costs.

No matter the risk, people who had experienced previous near-misses chose to evacuate at a lower rate than those with no knowledge of previous near-misses.

“It might be said that near-miss information changes people's frame of reference,” the researchers write. "A certain probability of hit that might have felt risky before feels less risky now because they escaped unharmed in the past."

Based on their findings, the researchers argue that emergency managers need to take the near-miss effect into account when communicating with the public.

"Those who educate the public about natural disasters need to realize that the same objective facts about the costs and statistically calculated risk of an impending hazard will be interpreted differently by people based on their own prior experience," the article notes."Since this near-miss influence seems to operate automatically, people may need explicitly to be taught to counteract their gut feelings."

♦ Photo of Hurricane Ike destruction by USACEpublicaffairs/Flickr [2]

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