Illusory face perception, a tendency to find human-like faces where none are actually present in, for example, artifacts or scenery, is a common phenomenon that occasionally enters the public eye. We used two tests (N = 47) to analyze the relationship between paranormal and religious beliefs and illusory face perception. In a detection task, the participants detected face-like features from pictures of scenery and landscapes with and without face-like areas and, in a rating task, evaluated the face-likeness and emotionality of these areas. Believer groups were better at identifying the previously defined face-like regions in the images but were also prone to false alarms. Signal detection analysis revealed that believers had more liberal answering criteria than skeptics, but the actual detection sensitivity did not differ. The paranormal believers also evaluated the artifact faces as more face-like and emotional than the skeptics, and a similar trend was found between religious and non-religious people.
Related to the pareidolia point: Paranormal and Religious Believers Are More Prone to Illusory Face Perception than Skeptics and Non-believers, Riekki et al 2012
Ironically, Razib Khan criticizes it for finding too small an effect size: http://blogs.discovermagazine.com/gnxp/2012/10/which-results-from-cognitive-psychology-are-robust-real/ (LW post; I disagree that we should expect a large effect size, see comments on Khan.)