BubbaRay says:

#3, pedro, try moving your mouse cursor to the left edge of the upper left line, you’ll see the line oscillates diagonally NW-SE only, same with the other pair of lines SW-NE. By hiding the line endpoints, the illusion becomes real. Just get some post-it notes and cover the unoccluded diagram line endpoints for yourself – same effect.

If you’re interested, a bunch of these great optical illusions can be found here (including the one posted):

http://www.michaelbach.de/ot/index.html

arch says:

no … it is the same graphic.

here’s the thing, if you say cover the corners with your fingers, you actually have to summon the manual dexterity to actually properly cover the corners.

the whole point of the illusion is that the gaps effect the brain’s perception of the motion … if you haven’t managed to cover the corners, and hence not obscure the active element of the illusion, then it’s no surprise that you are getting confused.

… but not confused in a good way … in the bad internet way, where you login, shout “fake”, and throw out time wasting accusations that we need to spend our time correcting
…. yeah that’s right, it’s not that you couldn’t co-ordinate thumb and fore-fingers, it ‘s the guy hosting a site about optical illusions that’s a liar and a cheat …. c’mon people, it’s not a race to the bottom, we’re not in a contest with youTube comments, put just a little bit of effort into it, please.

chris says:

while viewing the image, shift your vision to the bottom left side of your monitor for a bit…. notice in your peripheral vision you can see the diamond rotating…. look back , you will see the dual oscillation…..they are not different images.