People often see hidden faces in things. Depending on the circumstances, this is referred to as pareidolia, the perception or recognition of a specific pattern or form in something essentially different. It is thus also a kind of optical illusion. Pareidolia (/pærɨˈdoʊliə/parr-i-doh-lee-ə) is a psychological phenomenon involving a vague and random stimulus (often an image or sound) being perceived as significant. Common examples include seeing images of animals or faces in clouds. Carl Sagan hypothesized that as a survival technique, human beings are "hard-wired" from birth to identify the human face. This allows people to use only minimal details to recognize faces from a distance and in poor visibility but can also lead them to interpret random images or patterns of light and shade as being faces.[12] The evolutionary advantages of being able to discern friend from foe with split-second accuracy are numerous; people who accidentally identify an enemy as a friend could face deadly consequences.
