Optical Illusion

Here's another mind boggling optical illusion.
It uses the same principles as the one I've posted before, playing tricks on our mind using the dark/light contrast.



The inner circles are cycling through black and white, but they seem to be out of phase. However, no matter how hard it may seem, they're exactly the same color!

Press the remove border to check it out.
(I didn't believe that either, and cut two holes in a piece of paper to place over the screen to really make sure... and it is...)

If you want to read more about it and understand why this happens you can read it here.