We tend to overestimate the probabilities of unlikely events, and we tend to overweight the unlikely events in our decisions. This heuristic joins forces with the availability cascade (#13) and cognitive ease (#2) heuristics above. We are more likely to choose the alternative in a decision which is described with explicit vividness, repetition, and relative frequencies (vs. how likely). Potential for error: succumbing to fear mongers who manipulate data in favor of their cause.