1. Look across this picture. Does it look like its moving?
It’s not

2. Which center circle is larger?
This is a demonstration of the Titchener illusion. To most people, the center circle on the left will look smaller than the center circle on the right.

3. Here are the same circles again.

4. Do you believe A and B are the same color?
This is a dramatic illusion involving, among other things, local contrast. Most people find it hard to believe that the “dark gray” check outside the shadows is exactly the same color as the “light gray” check inside the shadow. On the next slide, you can see the proof of this illusion.

5. Here are the same tiles side by side
Here are the centers of the A and B checks expanded and placed side by side. The illusion occurs for several reasons. First, square B looks light because it is next to darker squares (a contrast effect). Second, it looks light because your eyes automatically make an adjustment for the fact that square B is in a shadow (you conclude that it’s actual color is lighter than it appears). Third, we all have a well established idea of what a checkerboard looks like, and we see the squares in this new board as we expect to see them.

6. There's a face... and the word liar
What do you see?
What do
There's a face... and the word liar

7. It's a spiral, right?
No, these are a bunch of independent circles

8. Keep staring at the black dot
Keep staring at the black dot. After a while the gray haze around it will appear to shrink.

9. Stare at the black lightbulb for at least 30 seconds
Stare at the black lightbulb for at least 30 seconds. Then immediately stare at a white area on the screen or at a sheet of paper. You should see a glowing light bulb!

10. Which wheel is moving?

11. Examine the picture back and forth
Nothing is moving

12. How many colors do you see?
There are only 3 colors: White, green, and pink. There seem to be two different shades of pink, but there is only one pink.

13. Do you see a couple or a skull?

14. Count the black dots!
There are 0

15. Figure out this one

16. Are the horizontal lines parallel or do they slope?
The lines are perfectly parallel. Measure them!

17. How many legs does this elephant have?

18. Which man is tallest?
They are all the same

19. Do you see the three faces?

20. Do you see the face? Or an Eskimo?

21. Which ones are spinning?
None

22. Move your head closer to and away from the screen
That’s right. It never moved

23. Which is longer, the line from A to B or the line from B to C?
Nope! They are the same. Measure it if you want.

24. Is the circle perfectly round?
Yes, it is

25. Watch the picture and move closer and farther from the screen
Watch the picture and move closer and farther from the screen. What happens?

26. Is this s perfect square?
Yep

27. How is this possible?

28. Advertising adds little images to convince you their products are good
Advertising adds little images to convince you their products are good. Even this simple ad by Fed Ex contains one. Do you see it?
Look between the E and the X. There is an arrow to show you they are moving quickly.

29. Which is longer?
Same length

30. How many prongs are there on the fork? Are you sure look again.

31. This corner house is a bit tricky
This corner house is a bit tricky. Question: Is the corner concave or convex? Use your palm to cover the upper half of the picture and the corner will be bulged out. However, if you cover the lower half, then it will seem as the inner corner. Amazing.                                                            
Question: Is the corner concave or convex? Use your palm to cover the upper half of the picture and the corner will be bulged out. However, if you cover the lower half, then it will seem as the inner corner. Amazing.

32. Are the purple lines curved or straight?

33. How many are spinning? - None

34. These lines are perfectly parallel

35. Try to say the color of the words, instead of actually reading them
Try to say the color of the words, instead of actually reading them. You will find it surprisingly difficult. The right half of your brain is trying to say the colors, the left half is trying to say the word itself. This brain teaser is used by mountaineers to test if their concentration is ok. (by J. R. Stroop).                                                          
Try to say the color of the words, instead of actually reading them. You will find it surprisingly difficult. The right half of your brain is trying to say the colors, the left half is trying to say the word itself. This brain teaser is used by mountaineers to test if their concentration is ok. (by J. R. Stroop).

36. Woman or skull?

37. Cliff above water? There is more to it.
Look carefully and you will see a woman and child. Once you see it, it can’t be missed