Relative Sizes category consists of hundred interesting optical illusions, but the problem occurs when you start understanding them. When you see one, it is if you have seen all. All of them start to look the same. This is probably why none of them were posted lately. Well, this time Alan Mountain ensured we get ourselves some fresh, and even more complex material! In the photo below you can see Jochen and Marita Wiesner interact with an installation at an exhibition called Tour of Senses in Dresden, Germany. As you see, the exhibition deals with senses and plays with our perceptions. If you don’t have a clue how this optical illusion was produced, you should check this hint. If you are still having trouble, you are allowed to see the solution.