Answer this simple question. Is the circle:
1. Half way up the pyramid?
2. Above half way up the pyramid?
3. Below half way up the pyramid?
At this point many viewing this optical illusion pause. They know it wouldn't be an optical illusion if it wasn't different then it seems.
At first glance (even second and third glance) the circle appears above the point that is half way up the pyramid. The truth is though the circle is exactly at the half way point.
Feel free to pull the ruler out and measure for yourself.