Contingency judgment is assumed to play a central role in prediction, control, and explanation. Here, the author consider the situation that has no relationship between two discrete events. In such“ irrelevant” situations, people often develop the belief that there is a positive contingency between the two events that are actually unrelated. The author review experiments that have been conducted on the contingency judgment in
the irrelevant situation during the last 40 years. We discuss about critical factors embedded in the experimental situations to lead people over-estimate zero contingency.