Imagine you're shopping for a car and have to choose between two nearly identical vehicles.
In one car, you'd face a 2 percent risk of death in the event of a crash. In the other car, the risk is only 1 percent - plus an additional risk of just 0.01 percent (1 in 10,000) that in an accident, you'd be killed by the air bag.
The first car is nearly twice as dangerous as the second. Yet in a fascinating recent study, most people said they'd pick the first car.
What's really interesting is that, when participants were told the tiny extra risk was due not to the air bag, but to other factors that might increase the force of its deployment, most of them correctly chose the safer second vehicle.
What's going on here? According to Andrew Gershoff, a marketing professor at the University of Texas, and Jonathan Koehler, a law professor at Northwestern University, who conducted the study, people are very sensitive to what feels like a betrayal by something that is supposed to make them safer - in this case, the air bag.
Edward Tenner calls such things "revenge effects," and cataloged them in a book called "Why Things Bite Back: Technology and the Revenge of Unintended Consequences." The Yiddish term is farpatshket, something messed up by an attempt to make it better.
Gershoff and Koehler may have stumbled across the reason people react irrationally to a whole range of safety devices. Take vaccines. Large numbers of people are afraid of vaccination because, on rare occasions, someone is harmed by it. But the much greater risk is forgoing vaccination.
The key to making better choices, Gershoff and Koehler found, is getting the emotion out of the process - for example, by avoiding provocative images of low-risk events, or viewing the relevant information graphically. People, they found, made more rational choices for strangers than for themselves.
But the real problem is that humans are just so bad at assessing risk. You'd think natural selection would have taken care of this. Our ancient ancestors wouldn't have survived very long if they were so busy worrying about getting cancer from wearing animal skins that they didn't notice any tigers lurking nearby.
But the modern world is vastly more complex than the evolutionary environment, and evidently we evolved to rely heavily on our emotions in deciding what to worry about. Maybe that's why, again and again, people become obsessed with vanishingly small risks.
The good news is that modern life is amazingly safe for parents, children and everyone else. Life expectancy increases all the time, and such formerly quotidian killers as childbirth and industrial accidents have been cut radically.
Consider traffic fatalities, a major killer for years. They plummeted from 43,510 in 2005 to 33,808 in 2009. That's the lowest level since 1950. And yes, the rate per mile and per capita is way down too.
Let's face it, the biggest threat to most of us is ourselves. Smoking isn't mandatory anywhere that I know of. Yet every year tobacco claims an astonishing 443,000 lives in this country. That's one in five deaths. And let's not even get started on what we do to ourselves with our own forks.
The great irony of all this is that worry is stressful, and stress is harmful to our health. Perhaps FDR had it more right than he knew when he said that the only thing we have to fear is fear itself.
Akst is a columnist for Newsday.