Psychologists Hillel Einhorn and Robin Hogarth (1978) have studied the general issue of why people persist in beliefs that are invalid, that is, why they succumb to the illusion of validity. Einhorn and Hogarth suggest that people do so because they are prone to search for confirming evidence, not disconfirming evidence. Consequently they not only may come to hold views that are fallacious, but they may be overconfident as well.