Japan’s 9.0 magnitude earthquake and subsequent tsunami and nuclear plant explosions have prompted thousands of news segments and blog posts on risk. Here in Los Angeles, we’re being inundated with risk calculations from experts and officials on a variety of potentialities – the risk of radiation exposure in LA from Japan among them (I was glad to know that risk is deemed "minimal" and "very remote").

The problem is that we humans don’t always respond to risk based on facts. According to author David Ropeik whom I interviewed a while back, in most cases we don’t even have all the data to begin with. “Evolution has taught us to protect ourselves immediately, before we have all the facts,” he said. “We are biologically hard-wired to fear first and think second.”

This instinctual reaction of fear drives our initial response to a risk, according to Ropeik, whose most recent book is entitled “How Risky Is It, Really?: Why Our Fears Don’t Always Match the Facts.” Risk communicators then must try to convince members of the public to override deep instinct in favor of the calculation of probability that exposure to a hazard will result in negative consequences.

In addition to trying to persuade someone to change their perception and overcome that initial fear, risk communicators also must battle myriad psychological factors that play an important role in how people view risk. 

Thirty years of research in the field of psychology have yielded a body of knowledge about how humans perceive risk.  A species-wide pattern of fear means that most people around the world fear the same things for the same reasons.  And often these fears don’t match the facts.

People are always afraid of a risk when it first pops up, according to Ropeik, and less afraid after it has been around a while. Remember fears about radiation from microwave ovens?

“We are also always more afraid of an imposed risk that one we choose,” he continued. For example, the dangers of radon gas seeping into homes, potentially causing lung cancer, pose a very scary threat to members of the public because it is imposed.  However, many many more people will contract lung cancer from smoking, but because that is a chosen risk, it is less frightening.

People are also less afraid of a risk when they can exert some physical control over it, which explains why bungee-jumping, sky-diving and skiing remain popular sports despite their riskiness.  It also explains why people who are afraid to fly are less fearful of driving the car, despite the much greater statistical risk of dying in an auto accident.

Catastrophic risks, such as an airplane crash, strike more fear in the hearts of individuals than do statistically larger risks that affect individuals rather than hundreds or thousands of people at once. 

The “dread factor” also plays a role.  “What’s worse,” Ropeik asks.  “Being eaten alive by a shark or dying in your sleep of heart disease?”  If you said the shark, you are not alone.  However, guess which one is more likely, and logically the one you should be more afraid of?

We perceive a risk as less negative if it is happening to “them” instead of “us.”  “We see risk through the prism of our vulnerability,” Ropeik said.  “Before 9/11, terrorism was what happened to other people – embassy workers, soldiers, people in other countries.  Now, it could happen to us, in our parks, in our homes, in our offices.”

Finally, we are much more afraid of risks to our children than to ourselves.  “What’s worse,” Ropeik asks again.  “Asbestos in your workplace or asbestos in your child’s school?  Our fear goes up if there is a potential effect on future generations.”

It may be impossible to change centuries of human evolution and train our brains to evaluate risk unemotionally. But perhaps awareness of our ingrained tendencies can help us take a balanced approach.