CSO Disclosure Series | Reporter's Notebook: The United States of TMI

Lead paint in toys. Brain-eating amoeba. Identity theft. Drowning in sand. We know more than ever about the risks all around us. Do we know what disclosing them all is doing to us?

e risk analysis, that make us feel just how rare certain risks are. Make the analytical seem intuitive.

It’s difficult to do this well. For example, Slovic remembers once when he was trying to explain chemical risks that occurred in the parts-per-billion range. People can’t relate to what a part-per-billion means, “so we said one part per billion is like one crouton in a thousand-ton salad," he says. He thought people would get that. Unfortunately the analogy backfired. It made people exaggerate the threat, not downplay it. Why? "Because I can imagine a crouton," says Slovic. "I can hold it in my hand, and eat it. I can’t really picture what a thousand ton salad looks like. So I focus on the risk, the crouton, because I can’t compare it to a salad that I can’t even imagine."

Another common mistake when putting risk in context is to use the wrong numbers, specifically focusing on multipliers instead of base rates, says Fischoff. For example, cases of the brain eating amoeba killing people have tripled in the past year. Yikes! That’s scary, and good for a news story. But the base rate of brain-eating bacteria cases, even after rate tripled, is six deaths. One in 50 million people. That’s less scary and also less interesting from the prurient newsman’s perspective.

But even that “one in 50 million” characterization is problematic. It still causes people to exaggerate the risk in their minds, a phenomenon called "imaging the numerator." In one experiment that showed the dramatic effect of imaging the numerator, Slovic notes, psychiatrists were given the responsibility of choosing whether or not to release a hypothetical patient with a violent history. Half the doctors were told the patient had a "20 percent chance" of being violent again. The other half were told the patient had a "one in five" chance of being violent again.

Startlingly, the doctors in the "one in five" group were far more likely not to release the patient. "They lined up five people in their minds and looked at one of them and saw a violent person." They imaged the numerator. On the other hand, 20 percent is an abstract statistic that hardly seems capable of violence.

It sounds illogical, but our minds think that "one in five" is riskier than "20 percent."

ESPECIALLY WITH PARENTS, one of those illusory controls we use to manage so much risk disclosure is to look at our own experiences,