They are related to your pressure level.
If you see them to move, then that means you have pressure currently.
The speed of the moving is the level of your pressure.
The higher that moving speed, the higher pressure you have.
Most children and old men only see the pictures are not moving and keep still.
I saw them move in a slow motion, that's mean I have a bit pressure currently.
Test yourself regularly with these pictures to know yourself better.
Sometimes, it is good to have a appropriate pressure to push us to do better,
but too much pressure can cause us to the end of the edge.
Be relax when you know you have too much pressure inside !
