This image was created by a Japanese neurologist. If you are calm, it doesn't move.
If it moves, you're a little stressed. If it moves a lot, you are very stressed.
I think it's false, that it's an optical effect by which we all see it animated
I am thinking that maybe all of you are right. Maybe when you are not calm your eye makes more movements and you get the effect that @lucas has mentioned.
Growing evidence suggests that sleep plays a key role in regulating emotions. Rapid eye movements (REMs) in REM sleep could be associated with dreams emotions, but supporting evidence is indirect. To highlight this association, we studied the REM sleep during video-polysomnography of 20 subjects...
www.nature.com
It looks like the emotions stimulate a part of the brain called amygdala but the paper reports that its reaction triggers REMs on sleep. Strangely though I am not calm but in a positive way since before some time my team has achieved a great victory against their biggest adversary in their home stadium.
I suppose this is why I am ready to select a letter after the wheel of fortune has turned.