3.  Aparently this Coca Cola advert is normal, but… Did you read well? With a naked eye you see the name of the brand and you don’t realize that the image is tricky. It is a consequence of the effect STROOP which is produced by the automaticity of reading. We know what is written and we don’t pay attention, we take it for granted.

5.  Although, they don’t seem they are straight and parallel lines. The sight is deceiving us; thin lines of the background that go out of the black circle provoke an illusion. They make us think that the thick lines are getting away from the central part.

6. The old woman and the young woman. Some of you will see in this image a Parisian old woman, the others will see a Toulouse-Lautrec young lady. Pay attention because they are both in the image. What an observer sees, depends in a great way, on his knowledge and expectations, therefore being the same image, we see different things.

7. Why do you see a cube in an image formed by circles separated from one another? Psychology says that because those elements line up in a straight line or in a smooth curve we identify them as integral parts of an unique form, although, they stay separate from one another.

8. Can you see a skull in the foreground? And a romantic scene? Look more closely, because in the centre of the image there is a couple of lovers declaring love for one another. This double-image effect is often used by painters and draftsmen.

9. Look at the window. What is the authentic perspective? Is it overlooking up or down? They are both possible and you only need to look attentively to realise that. This is another optical effect created by draftsmen where they try to present a double perspective in approaching an image.

10. Here we can see some workers working in a house. What is not clear is whether they are making a terrace, a roof or a floor. What is more, there is somebody watching from the top how they are doing it.

11. Observe attentively these two figures. Could you tell which of the two red circles in the centre is bigger? The one on the right or the one on the left? If you have answered any of the questions you are wrong. Both circles are exactly the same. What make us interpret falsely are the circles around – we compare the red internal circle with the ones more adjacent in a way that we see them bigger or smaller in a relation with the latter ones.

12. This road is apparently level but it seems to lead to the first floor. How is it possible? It’s clear that this construction is not possible in reality. Our sight is deceiving us.

13. Now pay attention to this drawing... We suppose that we see an image of a priest praying. But what happens when we turn it upside down?

14. In this painting you can see more then you can imagine. Sharpen your sight and your wit and find nine people that are hidden in this illustration. If you will not find them there is a solution:

15. 1) Face in the sky. 2) Profile of a face in the sky. 3) Profile of a face in the sky. 4 ) Profile of a face in the sky. 5) Profile of a face in the sky. 6) Woman in a long skirt. 7) Child in the arms of that woman. 8) Old man in a hat and with a white beard. 9) Profile of a big face formed by an arch, the woman and the old man… and a dog that is his hand resting on his chest.

16. It’s clear that this is a vase but… also there are two man facing each other. Can you see their profiles on the dark sides of the vase?

17. Pay attention at this piece of work of Salvador Dalí. We see a group of people in a pure surrealistic style. But there is also a portrait of Voltaire in the foreground. Two of the females’ faces are the eyes.

18. There are two animals in the image you are looking at. Can you see them? One of them is a head of a duck and the other one is a rabbit each of them looking in the opposite direction.

19. These two guys are sitting on different steps but look well. Do you think that it could be real?

20. These horizontal lines don’t seem parallel at all but they really are. The position of the black squares are responsible for this false optical illusion. They make us understand the image in a wrong way. Check it out.

21. It is easy to get confused and this is exactly what our draftsman wants creating an image of this fantastic animal.

22. It seems that the right one is, doesn’t it? In reality they both measure exactly the same. You can check that if you want.

23. but there is also a saxophonist playing; can you see him?

24. It could never exist in reality. Its sides are impossible to construct in 3D.

25. But if you look carefully you can also see an inside of a room where there is a cat looking, a shelf with a bottle and a plant (at the very top on the left), a curtain on the right side, a glass in the centre of the windowsill and clothes hanging outside. Are you capable to see both versions of the image?

26. there are two or maybe three…

27. What is more, if you look at the picture for some time you can notice that the vision unwittingly changes from the upper view of the stairs to the lower view.

28. Our sight is deceiving us again

29. Measure them and check

31. In reality there are only three colours in the picture: white, green and magenta but as some of them are concentrated very close to one another we believe that we see different colours

32. This drawing of a bunch of flowers also hides profiles of 5 people. Can you find them?

33. But if we would turn the picture upside down...

36. When you look at this image you think that everything is deformed but if you focus you can see that the lines that form these ruled squares are straight and perfectly parallel. What make you confused are the little white squares. They make your brain associate them with the other white squares and store them together.

37. Look carefully at this circle for a few minutes – does is seem to move?