Illusory Correlation .refers to the perception of a relationship where None exists.It is the tendency to see relationships, or correlations, between events that are actually unrelated
Illusory correlations help explain many superstitious and erroneous beliefs such as the presumption that the full moon causes abnormal behavior, that sugar makes children hyperactive, and that weather changes trigger arthritis pain.
As noted by David Myers, once “we believe there is a relationship between two things, we are likely to notice and recall instances that confirm our belief†(2004, p. 33).
We especially have a tendency to notice a relationship between distinctive or unusual events, say the thought of a song and it then coming on the radio. The problem in this situation and many others fueled by the illusory correlation is that we fail to consider other important information. For example, to fully evaluate this event we also have to consider the instances when the song was played on the radio and we weren't thinking about it and the times when we were thinking about the song and it wasn't played on the radio. Each piece of information is equally important in thinking critically about such events, though we are less likely to notice these latter instances as they are not distinctive.