The 'availability heuristic' which influences your fears

Our memories can have a dramatic influence on how we assess probability and risk. Take for example the fact that “terrorist attacks” rank among Americans’ greatest fears, when they are thousands of times more likely to be killed by a gun. This is partly because of the availability heuristic, which is our tendency to judge the likelihood of events based on how easily and clearly examples come to mind

The availability heuristic

is a judgmental heuristic in which a person evaluates the frequency of classes or the probability of events by availability, i.e., by the ease with which relevant instances come to mind. Consequently, the reliance on the availability heuristic leads to systematic biases. Such biases are demonstrated in the judged frequency of classes of words, of combinatorial outcomes, and of repeated events. The phenomenon of illusory correlation is explained as an availability bias. 

his paper explores a judgmental heuristic in which a person evaluates the frequency of classes or the probability of events by availability, i.e., by the ease with which relevant instances come to mind. In general, availability is correlated with ecological frequency, but it is also affected by other factors. Consequently, the reliance on the availability heuristic leads to systematic biases. Such biases are demonstrated in the judged frequency of classes of words, of combinatorial outcomes, and of repeated events. The phenomenon of illusory correlation is explained as an availability bias. T