The authors explain "mental models" — "a person's thought process for how something works." Understanding the audience's mental model and its inherent biases is key to successfully imparting information.
There's an interesting example from Anthony Leiserowitz, director of Yale's Project on Climate Change. He has observed that mental models of the ozone layer hole and climate change are often conflated, and that this conflation leads to inaccuracies.
Paradoxically, this conflation is due in part to scientists' and the media's success in communicating the gravity of the ozone problem in past decades. Legislation followed and CFCs are (almost) phased out. But now, as the public grapples with a different issue — climate change from "greenhouse gases" — some wonder why we can't just bring back CFCs to reopen the ozone hole and release the trapped heat.
The problem is with the "greenhouse" metaphor. The two descriptors — "ozone hole" and "greenhouse gases" — have together fostered a misconception of how the science behind human-induced climate change works.
Presumably, if a communicator knows about this faulty mental model in advance, he can account for it in his explanations and, it's to be hoped, even correct it.
People don't have an infinite capacity to worry, note the authors. Researchers call that limited fretting capacity "a finite pool of worry." And there's competition for space in this pool. If a person begins worrying about one risk, he or she will likely begin worrying less about another. In this constant competition, short-term threats beat out long-term ones.