Pareidolia

This is a psychological condition in which the brain falsely creates meaningful patterns, usually pictures of the human face, out of random patterns. This ability lies behind many supposedly miraculous appearances, such as that notorious face on Mars, the image of Jesus Christ on the wall of a church in Ghana last year, or even the Man in the Moon. It can be auditory instead, which has led to the paranormal episodes known as electronic voice phenomena (EVP), in which people claim to hear messages in the random noise of audio recordings. The word is from Greek para-, almost, plus eidolon, the diminutive of eidos, appearance or form.

As to the image ... it is nothing more than the human ability called pareidolia to interpret essentially random patterns as recognizable images — such as seeing the face of the Man in the Moon.

Skeptical Inquirer; 3 Jan. 2005

The talents of people who believe in the paranormal don’t end there. It seems that they are also better than non-believers at perceiving meaningful patterns in apparently random noise. The classic example of this trait, which is known as pareidolia, is when people claim to see images of the Virgin Mary, say, on the wall of a building or a tortilla.

New Scientist 28 Jan. 2006