This passage comes from Nobel Prize-winning economist Daniel Kahneman's2011 book, Thinking, Fast and Slow:

An availability cascade is a self-sustaining chain of events, which may start from media reports of a relatively minor event and lead up to public panic and large-scale government action. On some occasions, a media story about a risk catches the attention of a segment of the public, which becomes aroused and worried. This emotional reaction becomes a story in itself, prompting additional coverage in the media, which in turn produces greater concern and involvement. The cycle is sometimes sped along deliberately by ‘availability entrepreneurs,’ individuals or organizations who work to ensure a continuous flow of worrying news. The danger is increasingly exaggerated as the media compete for attention-grabbing headlines. Scientists and others who try to dampen the increasing fear and revulsion attract little attention, most of it hostile; anyone who claims that the danger is overstated is suspected of association with a ‘heinous cover-up.’ The issue becomes politically important because it is on everyone’s mind, and the response of the political system is guided by the intensity of public sentiment. The availability cascade has now reset priorities. Other risks, and other ways that resources could be applied for the public good, all have faded into the background.

Did the brutal beheading of two (now three) Westerners by IS touch off an 'availability cascade'? Discuss.

(H/t Dart-Throwing Chimp, @Robert_E_Kelly.)