This is the illusion which can cause harm to your eyes if you look continuously .Try looking at it for 45 sec and then see the wall you will see some radiations of this kind coming out of your wall too

This is actually not true in all cases.Just because some people see what they percieve,it has been stated here

See these pole line and try figuring it out that whether the two horizontal lines are equal or not.Most of the people on the first try say they are not equal but when seen carefully you can see that they are actually of same length

What do you see in this optical illusion? Different people tend to see different things in this illusion

Concentrate on the center point of the circle and you will see that it starts moving as well as expanding.Actually it the lines are the same and are not moving.This is just an illusion to your eyes

Do you see these two poles parallel ? No..now try seeing eah of them individually..they are perfectly straight with respect to the same ground level

Still they are not parallel ..This is Illusion