Hollow Face Illusions
Overview: Our eyes, and brain are used to seeing objects in a certain way, ie noses stick out. When our eyes see something not conforming to the norm our brain tells us “that can’t be right” and it “corrects” it to what it believes we should be seeing.
Supplies: Einstein inverted mask, printed Gardner’s Dragon templates, scissors, tape
Objectives: How do our eyes perceive depth?
Setup:
- Place the mask of Einstein’s face on top of the light source with the inverted side facing the audience (his nose is furthest away from them).
- Try to match the height to as eye-level as possible.
How to run the demo:
- Turn on the light source, move from side-to-side, crouching and standing, and watch Einstein’s eyes follow you!
- For the dragon (and other animals) templates, look at the eyes and move side to side like with the Einstein mask.
What’s Happening?
In order to perceive depth and distance, our brains use various cues to make a “best guess”. These cues can be features like shadows, distortion, relation to objects at a known distance, or elevation.
When looking at an object like a face, our brains typically expect the contour to push outwards, as humans and animals that we see have faces with a convex shape. In addition, we generally expect lighting to come from above as with sunlight and room lighting. Our brains can gather information on the contour as the sharp transitions of lighting, and the gradual shift in shading gives us information about depth. So when an inverted object is illuminated from below, our brains perceive this as a 3D object illuminated from above.
Try this:
- Having trouble seeing the illusion? Look through a camera or try taking a video.
- It helps some people to close one eye at first, and be sure to view the object at eye level.
- To make your own Gardner’s Dragon, print out the following template and follow the instructions that are written around the outside. It takes a little bit of practice to get the correct mountain/valley folds around the face, so remember that the eyes should be pointing inward. Gardner’s Dragon Template
Learn more: (external links)