[James Snover]

Often you are only seeing a reflection of the blood vessels in your own eye. The little spots moving in those squiggly little tracks are individual blood cells. Optics, what a gas.

Here's a couple more for you: the larger the pupil of the eye, the less depth of field you have. Ironically, many people find they can judge distance better when their depth of field is shallower.

Another one: most people's eyes have different magnification values. Don't think so? Find something of a known size. Look at it with both eyes open. Then close one eye. Is the target object the same size? Close both eyes again, then open the other eye. Still the same size? You have to pay attention, because the brain tries to null this out for you.

People can see polarized light. Takes a while, but you can train yourself to do it. Make a pistol shape with your thumb and index finger. Point the finger at the sun. Where your thumb points is the zone of polarization. When you notice that part of the sky being darker than in the direction of the thumb, congratulations you're seeing poarized light. For the longest time it was assumed humans can't do this because we don't have compound eyes. Artists and photographers said you could, but who ever listens to them?

Do not get me started on color vision. Just don't do it.

Jim Snover