Too much dopamine.
As scientists probe deeper into the brain for what underlies superstition, they have found a surprising suspect: dopamine, which usually fuels the brain's sense of reward. In one study, two groups of people, either believers in the supernatural or skeptics, looked at quickly displayed images of faces and scrambled faces, real words and non-words. The goal was to pick out the real ones. Skeptics called more real faces non faces, and real words non words, than did believers, who happily saw faces and words even in gibberish. But after the skeptics were given L-dopa, a drug that increases dopamine, their skeptical threshold fell, and they ID'd more faces and words as real.That suggests that dopamine inclines the brain to see patterns even in random noise.