Can You Solve This Shadow Illusion?

A card with a small round hole is held up to cast a shadow on a wall.

• Participants predict they will see the shadow of the card with a hole in it • The hole is expected to appear in the shadow

The shadow shows the card and hole, though the hole shadow is not very pronounced.

The experiment successfully demonstrates the basic shadow projection concept.

Participants are asked to predict the relative size of shadow circles from cards with different sized holes.

• One participant predicts the hole with the larger card will produce a bigger shadow • They estimate it might be twice the size

Both shadows appear approximately the same size, with one being fainter than the other.

Participants express disbelief that the shadow sizes are identical despite different hole sizes.

A card with a triangle hole instead of a round hole is introduced.

• First participant confidently predicts a triangle shadow • Second participant suspects it might be a circle based on previous results

The shadow appears as a circle, not a triangle, defying expectations.

Participants begin to realize the sun is playing tricks on their perception and there's a pattern emerging.

Participants struggle to explain why all shapes appear as circles regardless of the hole shape.

• Removing definition from shapes makes them appear round • The sun appears round, which might be related

The light passing through the holes is actually sunlight creating circles that are projections of the sun itself.

One participant recalls learning about pinhole cameras in photography class, realizing the hole acts like a camera lens projecting an image of the sun onto the wall.