We regularly receive pictures in which people find some amazing faces. While some of these are very compelling evidence of ghost activity, others may be what's often called, in the ghost hunting community, "matrixing" - the effect of seeing images and faces in inanimate things, better known as pareidolia.
The scientific term for seeing human faces in inanimate objects, such as the moon or sky, is "anthropomorphism," and may be defined as "to give human attributes to non-human things." The idea of seeing faces in different objects or within patterns is something we do naturally as we try and identify with the world around us – a trait of human behavior. Anthropomorphizing happens when the human brain and eye work together to see shapes and patterns, collectively, as familiar, anthropomorphic (human-looking) images.
Some famous examples of anthropomorphism are the faces of Jesus and Mary appearing on grilled cheese sandwiches, pita bread, toast, walls and the like. These pictures are not spirits, ghosts, angels or saints. They are a coincidence of shapes that mimic the faces of people.
Slideshow photo examples of anthropomorphism - seeing faces in objects: While these are very good images of people's faces, are they really Jesus or Mary? Take a look at Jesus on a tortilla, Jesus on a grilled cheese sandwich, Mary on grilled cheese, Jesus on a dental X-ray, and Jesus on a pita.