I'd call the phenomenon 'looking at a pair of reflective
, symmetrical, rotating objects in front of a mirror
'. If you've been up way too long, and have lots of nice visible blood vessels, try this experiment:
- Look at the mirror, and align your finger with a blood vessel
of your choice
- Tip your head to one side
- Note that your finger and the blood vessel don't line up anymore.
What might be happening here is a combination of many factors:
1 - Your brain
has a mechanism whereby any voluntary movement of your head
s is compensated for, and so the world doesn't seem to move
when your head does.
- Close one eye, and look at something
- Through the eyelid of the open eye, push on the cornea, so the eye is moved to look at something else
- The world seems to move
(When drunk, the alcohol in the bloodstream changes the density of the fluid in the ear, making the balance sensors in it also detect gravity (Try tipping your head the other way when the world is spinning... It will start to spin the other way...). This also breaks the visual system, which is why the world appears to spin.)
2 - Eyeballs have rotational symmetry
, making it difficult to observe rotation about their axis
, unless they have a convenient marking.
3 - Eyeballs are wet and shiny; pretty good mirrors. They reflect
objects pretty well, and when they are rotating, the reflected image will stay still, creating the impression that the eyeballs are rotating.
4 - You're expecting it to happen, so it does.