Perhaps more important, research demonstrates that many people fall prey to a phenomenon that University of Wisconsin–Madison psychologists Loren and Jean Chapman termed “illusory correlation”—the perception of an association that does not in fact exist. For example, many people who have joint pain insist that their pain increases during rainy weather, although research disconfirms this assertion. Much like the watery mirages we observe on freeways during hot summer days, illusory correlations can fool us into perceiving phenomena in their absence.