"This is another main reason why I believe paranoia is on the increase. Because we are constantly reminded, in the press, of threats from other people, we overestimate the chances of these events happening to us. There is a lot of research on this. It is what is known as the 'availability heuristic'. We make an estimate of the likelihood of a particular event simply by how easily we bring it to mind. Our children are getting fat because we aren't letting them out to play enough. We're scared they will be run over or abducted by strangers. In fact, the risks to the health from obesity are much higher than the risks of either of those events."