While psychologists can’t know exactly what goes on inside our heads, they have, through surveys and laboratory studies, come up with a set of traits that correlate well with conspiracy belief. In 2010, Swami and a co-author summarized this research in The Psychologist, a scientific journal. They found, perhaps surprisingly, that believers are more likely to be cynical about the world in general and politics in particular. Conspiracy theories also seem to be more compelling to those with low self-worth, especially with regard to their sense of agency in the world at large. Conspiracy theories appear to be a way of reacting to uncertainty and powerlessness.
Why Rational People Buy Into Conspiracy Theories, an interesting article over at the NYT for those interested in knowing the latest research about this particular topic.