Pareidolia (/pærɪˈdoʊliə/ parr-i-DOH-lee-ə) is the tendency for incorrect perception of a stimulus as an object, pattern or meaning known to the observer, such as seeing shapes in clouds, seeing faces in inanimate objects or abstract patterns, or hearing hidden messages in music. Pareidolia can be considered a subcategory of apophenia.
Common examples are perceived images of animals, faces, or objects in cloud formations, the Man in the Moon, the Moon rabbit, and other lunar pareidolia. The concept of pareidolia may extend to include hidden messages in recorded music played in reverse or at higher- or lower-than-normal speeds, and hearing indistinct voices in random noise such as that produced by air conditioners or fans.
Pareidolia was at one time considered a symptom of human psychosis, but it is now seen as a normal human tendency.
Pareidolia is not confined to humans. Scientists have for years taught computers to use visual clues to "see" faces and other images.
Satellite photograph of a mesa in the Cydonia region of Mars, often called the "Face on Mars" and cited as evidence of extraterrestrial habitation.
A more detailed photograph taken in different lighting in 2001 shows how it is a natural rock formation.