Let me start with two simple questions.
1) Who is more likely to be apprehensive about catching a sexually transmitted disease, A or B?
A) A chaste person
B) A promiscuous person
2) Who is more likely to worry about banging their head on the top of a doorway, A or B?
A) A very short person
B) A very tall person
In both cases the answer is obviously B, because the risk of catching a sexually transmitted disease or banging your head on the top of a doorway are directly correlated with how much multi-partner sex you have and how tall you are.
Now consider a third question.
3) Who is more likely to worry about a terrorist attack, A or B?
A) Someone who has a relatively low risk of being the victim of a terrorist attack
B) Someone who has a relatively high risk of being the victim of a terrorist attack
You'd think the answer ought to be B again, but in this case I'm not so sure. I think there is something about the human spirit that confounds expectations when the danger is terrorism. Let me explain.
Consider two people - Jack and Bob. Jack lives and works in
He commutes to and from work every day, and he eats and walks in central London every day. Bob
lives in London Oxford, and visits only very occasionally - no more than
once a year. Which one of them is at the highest risk of being the victim of a
terrorist incident? By a long way, the answer is Jack. He spends nearly every
day in the city in the London
that is by far the most likely to experience a terrorist incident, whereas Bob
only visits the terrorism hotspot once annually. UK
But here's the interesting thing; I'll bet on that one day in the year when Bob is on the same London tube line as Jack, it is Bob who is most apprehensive about there being a terrorist attack, not Jack. It might be true that if you add up the total apprehension felt by both men in a year including calculating journey times, Jack has more aggregate apprehension, but the specific point I'm making still, I think, holds - which is that humans tend to greatly exaggerate small probabilities - and someone commuting in London every day is less likely to overestimate the probability of his being involved in a terrorist incident than someone who visits London once a year.
The other part of this is that terrorism engenders a fear and apprehension that is incommensurably greater than the actual probability of being a victim of terrorism - so an infrequent visitor to London would be more likely to have associative fear in relation to the spectre of terrorism than a regular commuter would have, because the latter has more acute daily experiences of the fact that terrorism is the exception to the regularity of everyday London-based activity, not the rule.