Of course, our experience concerning such people also involves exposure to media. The selective-availability problems that arise because the media se… - Robyn Dawes

Two biases of memory, however, tend to enhance the illusory nature of our retrospective “understanding” of our own and others’ lives. The first is that we tend to overestimate specific events relative to general categories of events. The second is that we tend to recall specific events and to interpret them in ways that make sense out of a current situation—“sense” in terms of our cultural and individual beliefs about stability and change in the life course. Thus, memories, which appear to be beyond our control as if we are observing our previous life on a video screen, are like anecdotes in that they are often (inadvertently) “chosen for a purpose.” The result is that they will tend to reinforce whatever prior beliefs we have, just as anecdotes tend to reinforce the points they are meant to illustrate.

A particular example (i. e., of irrationality) involves interviews. Despite all the evidence about the uselessness of interviews in predicting future behavior, people remain convinced that some people—especially themselves—are superb at “psyching out” other people during an interview. In contrast, the research indicates that interviews are effective only insofar as they yield information they could more consistently and more validly be incorporated into a statistical model. One problem, of course, that leads to the belief in the superiority of the unstructured interview is that it is, in fact, not studied; there is almost no systematic feedback to most interviewers. Much of the time, the interviewer is in a particular position in an organization and never sees the interviewee again. Second, if the interviewer does see the interviewee later, then that means that the interviewee has been accepted, which often implies fairly reasonable performance. Moreover, it is always possible to rationalize failures.

Believing you’re good at something just because you do it—without any information that you’re doing it well—is indeed irrational.