Pareidolia

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, a form of apophenia. Common examples include seeing images of animals or faces in clouds, the man in the moon or the Moon rabbit, and hearing hidden messages on records when played in reverse.

The word comes from the Greek words para (παρά, "beside, alongside, instead") in this context meaning something faulty, wrong, instead of; and the noun eidōlon (εἴδωλον "image, form, shape") the diminutive of eidos. Pareidolia is a type of apophenia, seeing patterns in random data.

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. The evolutionary advantages of being able to discern friend from foe with split-second accuracy are numerous; prehistoric (and even modern) men and women who accidentally identify an enemy as a friend could face deadly consequences for this mistake. This is only one among many evolutionary pressures responsible for the development of the facial recognition capability of modern humans.

In the attached figure, a fellow investigator sees a woman holding a baby in the bottom window. Pareidolia or a real apparition?