Grilled Cheese Jesus.  The Face On Mars.  The Man in the Moon.  The ghost head of a Tyrannosaurus rex spotted in a curl of smoke in a picture of Neil Gaiman.  What do all these things have in common?  They are all excellent examples of pareidolia.

Pronounced "pa-ri-DOE-lee-a," pareidolia is an innate quality of the human mind that makes us see things in chaos.  If you have ever seen subtle patterns marching across a television screen of static (do they even have those anymore?) or made shapes out of the clouds in the sky, you have exercised a little pareidolia.

In ghost hunting circles, pareidolia is called "matrixing."  This frequently turns out to be the explanation for ghosts spotted in photographs, and for the results of some EVP sessions.  (Some people argue that almost every piece of EVP evidence is simply the result of matrixing on the part of the listener, perhaps aided by static bursts, or accidentally recorded electronic cross talk from broadcast stations and CB radios.)

Many people saw ghost faces in a photograph Roger Ebert recently snapped, of a stag in the fall woods.  He posted this picture to his blog, and soon people were seeing ghost faces everywhere - in the mist, in the stag's breath, in the clouds and the patterns of dappled light in the leaves, and in the bark of the trees.  This exercise in crowd matrixing was impressive indeed.

Pareidolia shows up in a lot of odd places.  For example, many forms of divination rely on pareidolia.  In tea leaf reading, the psychic spots pictures formed by the tea leaves in the cup, and bases their fortune accordingly.  Older forms of divination such as scrying and the reading of entrails similarly leverage pareidolia.

The Rohrschach Test is an instance where the viewer's pareidolia is turned inwards, to expose the inner condition of the person being tested.  Everyone who looks at an ink blot will see something a little different, and what you see in the inkblot is often the result of your mental state being projected out upon the world.

One of the most fascinating aspects of pareidolia is that it is so pervasive and reliable.  Humans of every age, from any culture on the planet, will look at a stick figure and see a human being.  This speaks both to our capacity for abstract thought, and to some interesting evolutionary questions.

Carl Sagan hypothesized that pareidolia is a valuable evolutionary asset, because it allowed prehistoric humans to spot friend from foe in an instant, or see an animal standing in a dense thicket of brush.  It turns out that we do indeed have a tiny center of the brain which is dedicated to facial recognition.  This center (the ventral fusiform cortex) is hard-wired to light up when a face is spotted. 

However, the ventral fusiform cortex is only part of the story.  Our ability to see the most fanciful images in a collection of chaos has as much to do with our imaginations and our storytelling skills as it does a biological urge.  Put simply, pareidolia is one of the things which truly does separate us from animals; a quintessential part of what it means to be human.

Photo credit: Flickr/NUCO