It looks to me like a feedback loop. Fear in the populace results in politicians and media responding to and magnifying that fear. Fearful news reporting generates better ratings in a fearful populace, which makes them more fearful. Similarly, fearful political rhetoric garners votes from a fearful populace, which makes them more fearful. This would imply that it's sensitive to small differences in initial conditions.
One thing that I'd bet makes a big difference is the existence and magnitude of other threats. The US and UK are pretty solidly secure right now. There are no major human threats present now or in the near future. Compare with the era you're talking about, in which our countries (and, of course, many others) were perpetually 15 minutes away from total annihilation at the hands of the Soviets, either because they decided to try to take over the world, or just because of some terrible mistake. I imagine one probably doesn't take a terrorist nail bomb too seriously when you legitimately think there's a real possibility that you and everyone you ever knew will be killed in a two-hour-long WWIII.
Perhaps we're geared towards thinking about existential threats, and if one isn't present, we'll magnify whatever we can find.
It looks to me like a feedback loop. Fear in the populace results in politicians and media responding to and magnifying that fear. Fearful news reporting generates better ratings in a fearful populace, which makes them more fearful. Similarly, fearful political rhetoric garners votes from a fearful populace, which makes them more fearful. This would imply that it's sensitive to small differences in initial conditions.
One thing that I'd bet makes a big difference is the existence and magnitude of other threats. The US and UK are pretty solidly secure right now. There are no major human threats present now or in the near future. Compare with the era you're talking about, in which our countries (and, of course, many others) were perpetually 15 minutes away from total annihilation at the hands of the Soviets, either because they decided to try to take over the world, or just because of some terrible mistake. I imagine one probably doesn't take a terrorist nail bomb too seriously when you legitimately think there's a real possibility that you and everyone you ever knew will be killed in a two-hour-long WWIII.
Perhaps we're geared towards thinking about existential threats, and if one isn't present, we'll magnify whatever we can find.