When the mind wanders, it sees faces...

A few days ago, I had the unfortunate experience of being stuck for a while in a room that was in need of renovation. There was nothing to read, nothing to do, and I couldn't move. My eyes had nothing else to look at than the stains and holes in the floor. Before long, the shapes started to take on meaning. There was a baboon, there was Mickey Mouse, and right before me was a fire-breathing dragon!

Mickey Mouse

It is interesting how we all see patterns in random things like clouds and stains. Who has never looked at clouds drifting across the sky, and seen people and animals? I often see maps of familiar countries and fictional worlds in the clouds. Trees and mountains can have faces and bodies, so clear that I can clearly understand where the myths of Trolls come from. 

This is called pareidolia. It is what happens when the brain interprets a random image as a familiar pattern. The single most common pattern generated in this way is a human face. Pareidolia is the phenomenon behind the "face of the moon", the inkblot test, and some say it is the reason why we can see a smiley icon as a smiling face. 

Naked woman throwing a hammer

There are many communities and blogs out there dedicated to pareidolia. All of them, at least the ones I have found, are filled with images of things that look like faces. All it can take is a pair of dots, and the human brain will interpret it as "looking at you". Even the word "look" contains a pair of eyes when we look closely at it! 

When I was a child, my bedroom had curtains with large brown flowers on it. That pattern gave me nightmares, because my young eyes saw a witch in the flowers. She was wearing cat eye glasses and a scarf. I couldn't understand why my parents' couldn't see the witch, when she was clearly staring at me from every flower on those curtains. In fact, I couldn't even see the flowers back then. I could only see the witch and some random swirls. 

Dragon breathing fire on the ground

A couple of years ago, my parents were cleaning in their basement and found those old curtains from the 70s. They took them up and draped them over a chair in the living room, because they thought I might be interested in taking them with me. There was the witch, staring at me! 

I don't have a picture of the curtains; they are in my parents' house. I do have pictures of the stained floor and its strange inhabitants. 

Pareidolia wikipedia article

Photo collection on Google+

A late night walk

I was just out for a late night walk. This September has been unusually warm, and I need the exercise. Walking, for me, is almost a form of meditation. While my body moves with its own automatic rhythm, my thoughts flow freely.  I lose track of time.

Something made me look up at the sky for a split second. I saw stars, and looked at the road again, but something felt wrong. Fundamentally wrong. My subconscious was feeding me a sense of dread, as if I had seen something impossible happen. This confused me; I had just seen stars?

I stopped and peeked at the starry sky again. Then I saw it. One of the "stars" was in fact a high flying plane, slowly moving across the sky, too slow to be noticeable but too fast to be anything else than a plane. Somehow, my subconscious had registered this subtle movement and interpreted it as wrong, because stars don't move.

It is amazing how the subconscious can filter the enormous amounts of sensory information we take in every day, and only pass on the relevant part to the conscious mind. It makes me wonder how much we miss because it isn't weird or dangerous enough to be noticed.

Did you know...that humans can see polarised light?

Light can be defined as a waveform. In normal light, the waves swing in all possible directions. When light is filtered so that all the light waves have the same direction, it is called polarised light. This is how polaroid sunglasses work, for example. Scientists use polarised light for studying mineral structure, and some say that animals may use patterns of polarised light in the sky for navigation.

This is what it looks like to me

Computer screens emit polarised light. This is a side effect of the way they work. The outer layer of a LCD screen is a polarising filter. It is possible to see this with our own eyes. This effect is called Haidinger's Brush.

It is easiest to see this if you stare at the screen for a few moments, then quickly tilt your head to the side. To me, the effect usually looks like a yellow, butterfly-shaped pattern, about 2 cm/1 inch wide. Once you have seen it, you can't unsee it!

Some people can see this effect also in the sky, especially close to the horizon where the daylight is most polarised.

Did you know...that some people can see ultraviolet light?

Ultraviolet light is usually invisible to humans. On the electromagnetic spectrum, ultraviolet lies "beyond violet". Its wavelength is too short for the human eye to perceive it. UV light can damage the eyes, even if we can't see it, and that's why sunglasses need to block it. Some species of animals, for example insects and birds, can see this light clearly and use it for finding their food.

But did you know that also humans can, under special conditions, see ultraviolet light?

People who have had their lenses surgically removed can see UV light as a white, blue  or violet light, according to this article in The Guardian. The reason for this is that the lens acts as an UV filter. The blue receptors in the retina are actually more sensitive to ultraviolet than to actual blue, according to professor Bill Stark.

This reddit thread has several interesting links and points about humans being able to see unusual forms of light. One poster suggests that by filtering out visible light completely, we'll also be able to see near infrared light. They suggest that the eye isn't completely blind to this wavelength, but so little sensitive that it is usually overpowered by conventionally visible light.