THE CASTLE GUARD WITH HIS TRIDENT



How many prongs do you see?
I see two on the bottom—but on the top, three

Solution: Cover the top of the trident and you see two prongs. Cover the bottom and the trident now has three prongs. You can draw this object, but you can’t construct it. (impossible-object illusion)


THE ROYAL MESSENGER ARRIVING WITH A LETTER FOR THE KING



The red tape on the letter is longer than the blue. But is this really true? Remember, now you are in OPT!

Solution: Angles are sometimes tricky! The red and blue tapes on the envelope are the same length. If you remove the outline of the envelope, you can see this. (geometrical-contrast illusion)


THE PRINCESS PICKING A SPECIAL BOUQUET



Flowers fair, flowers bright.
Which flower center is larger—the black or the white?

Solution: The black and white centers are the same size. The white center appears smaller because larger circles surround it. The black center appears larger because smaller circles surround it. (geometrical-contrast illusion)


THE OPT SIGN POINTING THE WAY TO THE ZOO



By the sign the royal family will stop. Which line is longer, the bottom or top?

Solution: Both lines are the same length. When the arrows point outward, the line appears shorter. When the arrows point inward, the line appears longer. (geometrical-contrast illusion)


THE BIRTHDAY PARTY FOR THE PRINCE



This gift, unwrapped, tells the Prince’s age.
This is what the dragon said,
“Six blocks become seven if you stand on your head. HAPPY BIRTHDAY!”

Solution: You don’t have to stand on your head! If you turn the book around, you should see seven blocks with white tops. The number of blocks you see depends on whether you view the boxes as having a white top or a white bottom. (reversible-image illusion)