From trying to figure out if a shape is actually moving to whether it's changing colour, the best optical illusions can really addle your brain.
Users on Quora were asked to pick out some of the 'great optical illusions'. Here are some of their choices:
Both the squares A and B marked in this chequerboard, designed by Edward H. Adelson, are the same shade of grey, however you may struggle to tell your brain that this is so.
You can see from the image below, where the shade of grey is run beside both of the squares that they are in fact the same colour.
The Freezing Rotation Illusion
Max Dürsteler, a former neuroscientist at University Hospital Zurich in Switzerland, designed this freezing rotation illusion.
In the video there is an interior circle rotating as the background sways back and forth. But is the internal circle turning smoothly all the time, or does it freeze occasionally?
The Impossible Motion
This illusion features slopes and magnets. Kokichi Sugihara designed it, and the wooden balls on the slopes seem to defy gravity by going up and down the slopes.
The Scintillating Grid
Can you see the black dots flash up throughout the picture? They seem to appear and then vanish at the intersections of the grids. If you move closer to the screen the effect seems to lessen.
The grid, discovered by E.Lingelbach in 1994, was a modification of the Hermann grid illusion.
Motion silences awareness of visual change
Watch the video below and keep your eyes fixed on the white dot in the centre of the ring.
At first, the ring stays still and the coloured dots switch colours. However, then the ring starts to rotate. If you're keeping your eye on the ring as it moves, it seems that the colours stay the same. If you stop looking at the white dot, you can see that the colours are still changing the same as before.
The colour-changing castle
In this video illusion, you need to keep looking at the black dot at the centre of the image of the castle.
At first, the castle is coloured in yellow, purple and blue. After a while, the picture changes and appears to be in full colour before changing to black and grey. It was all an illusion of course, if you scroll back the photo was in black and white the whole time after the jump.Reuse content