Which one of the two objects is bigger? They are both the same size although the yellow object obviously seems bigger.
Which of the three Chinese is the tallest ?
A little man is being chased down a hallway by a big bully. Maybe you should get a ruler, 'cause I'm starting to suspect the bully isn't that much bigger. In fact, this is twice the same man ! An intereresting observation is that even the expression on their faces seems to be different.
Have a look at the red lines on the drawing. They are exactly the same size ! There are a few explanations for this phenomenon, one of them being that the lines on the top and bottom suggest a perspective (which is actually drawn here). The illusion works fine without the ticket scene, too.
The tabletops are identical in shape and size ! I found this illusion to be so strong that I've opened it in Photoshop to see for myself ... And, well, that doesn't happen a lot.
The central spheres have the same size. You wouldn't say so because your perception is being influenced by the surrounding spheres. Also called the Titchener illusion. Just in case you were wondering : "Is that the same as the Titchener illusion" ? Yes !