Is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method or decision.
This is a cognitive bias as individuals tend to over-estimate the probability of an event occuring the more easily they can recall examples. For instance to put this bias to the test in an experimient individuals were asked to state which of the two options was more likely 'words beginning with k' or 'words where the third letter is k'. Most individuals wrongfully chose the former option as it is much easier to recall words that start with the letter k than it is with words where the thrid letter is k. Another example of this is to ask individuals to evaluate the probability of an airplane crash as the diagram below shows.
