What psychological phenomenon makes people see, for example, a face on the planet Mars?

Also the same sort of thing when persons "see" the likeness of Christ or the Virgin Mary in fog, on a piece of toasted bread etc.

Player #1489294, this is a Family Forum. Please leave out toast references. This is intended as a sarcastic remark.:-)

It reminds me about the woman in the short story the yellow wallpaper, the woman always see people struggling behind the pattern of a yellow wallpaper in her room, but thats a work about the release of a bounded soul.