If you were handed a can of bug spray, you might start killing a lot of insects around the house. And if you had reason to believe that the bugs were poisonous — maybe because your neighbor told you there was an infestation, or you had seen a show about creepy crawly things on the Discovery Channel — you might even become convinced that the little piece of lint under your bed was a nasty spider, curled up just waiting to bite you. Americans tend to overestimate both their risk of exposure to violent crime and their ability to judge...
