““With respect to the formation of erroneous beliefs, the implications of people’s difficulties in detecting covariation should be clear. By placing too much emphasis on positive instances, people will occasionally “detect” relationships that are not there. For many of the real-world phenomena that are of greatest interest, one is sure to encounter many positive instances even when there is no relationship at all between the two variables. Although there is surely no validity to the common belief that we are more likely to need something once we have thrown it away, examples of acute longing for a discarded possession may be easy to come by. By letting necessary evidence “slip by” as sufficient evidence, people establish an insufficient threshold of what constitutes adequate support for a belief, and they run the risk of believing things that are not true.””
