FR IT EN

Ambiguous Cube

Strange things can happen when your brain gets confused.
Some objects or figures are “ambiguous,” providing visual input that your brain can interpret in more than one way. In this Snack, you’ll construct a three-dimensional cube that exhibits ambiguous behavior when viewed with one eye.

Ambiguous Cube 2
Ambiguous Cube Mat

Tools and Materials

  • Twelve drinking straws, all the same length (avoid colorless transparent/translucent straws if possible)
  • Enough chenille stems (aka pipe cleaners) to provide eight 6-inch pieces when cut (you can find chenille stems online and in craft stores; they typically come in 12-inch lengths, but may come in other lengths as well)
  • Scissors
  • Optional: additional drinking straws and chenille stems; string
Ambiguous Cube 1

Assembly

  1. Cut the chenille stems so you have eight pieces, each 6 inches long.
  2. Bend chenille stems to form three-legged corner supports, as shown in the photo below.
  3. Build an open cube by inserting the corner supports into the ends of the straws (see photo below). Bend the corner supports as necessary to form the angles required.

To Do and Notice

Place the cube on the floor and stand two to three feet away. Adjust your position so you’re looking down at one of the cube’s vertical edges, not at one of its flat faces (see photo below).

Adjust your distance so the top corner nearest you lines up (approximately) with the center of the bottom of the cube, as shown in the photo below.

Close one eye and stare at the cube. Try to look “past” the cube—or concentrate your gaze on the bottom back corner and “will” it to move toward you. Try to avoid focusing your attention on places where the straws cross. If all works well, the cube should suddenly appear to be standing along an edge, or possibly on a corner, rather than on a flat face.

If you experience this effect, hold the focus of your gaze and gently lean slightly to the left, and then to the right. You should see the whole cube rotate in the direction you move.

Opening your other eye will normally destroy the illusion.

Note: In the field of perception, it’s unfortunately the case that some people will not experience the desired effect. If that happens to you, we offer our condolences!

What's Going On?

This three-dimensional cube creates an ambiguous figure because it can be perceived in two ways: one is the actual physical cube; the other—the “rotating” cube—is an illusion.

If you were successful in perceiving the illusion, the bottom back corner of the cube seemed closer to you than the top front corner. This happens because closing one eye hinders your depth perception, making it easy for your brain to ignore the cues provided by the places where the straws cross. Normally, your two-eyed stereovision gives you enough information to interpret the cube correctly, which is why the illusion disappears when you open your other eye.

Why does the reversed cube appear to rotate as you change your viewing position? Try this: Close one eye, hold one of your index fingers at arm’s length, and line it up with some faraway reference point, such as a picture on a distant wall. Move your head to the right and notice that your finger appears to move to the left relative to the distant object; move your head to the left, and your finger seems to move to the right. Relative to the distant object, your finger (which is the closer object), moves in a direction opposite to that of your head.

When you see the cube in its “rotating mode” and you move your head to one side, your brain expects the parts of the cube closest to you to move to the other side. But the parts of the cube that your brain perceives as being closest are actually the parts that are more distant—so they move to the right instead. Trying to make sense of the situation (as it always does), your brain interprets the visual input as best it can: It “sees” the object rotating to follow your gaze.

Visual illusions are fun to play with, but they are also the subject of serious study by neuroscientists. The “mistakes” our brains make provide insights about our process of perception.

Exhibit-Links
11762 Detail

Ambiguous Figures

Clearly ambiguous. One object, two forms: “Necker cubes” belong to the category of ambiguously perceivable objects. Perceiving spatial dimensions and depth:…

11763 11813 Detail I

Changing Sides

A wire cube rotates in front of a mirror. If you squint one eye and fix a front corner of the wire cube, you see a certain direction of rotation. If you now…

11763 11813 Detail I

Turning Shadow

Playing with the Pulfrich effect: perceiving a two-dimensional image as three-dimensional. Through the Pulfrich glasses, the shadow of the cube gains depth.…

thema-Links

Biology

Seeing

Senses

more to browse
Afterimage Main

Afterimage

A flash of light prints a lingering image in your eye. After looking at something bright, such as a lamp or a camera flash, you may continue to see an image of…

Agar Cell Diffusion DSC 0413 P960

Agar Cell Diffusion

Use cubes of agar to investigate how size impacts diffusion. All biological cells require the transport of materials across the plasma membrane into and out of…

Bacteriopolis Main

Bacteriopolis

Make a home for a colorful community of microorganisms. This endlessly fascinating living artwork reveals the colorful microorganisms living in the mud and…

Bean Counter Main

Bean-Counter Evolution

Hunt for prey and discover the meaning of evolutionary “fitness” in this physically active group game. In this simulation game, teams of predators equipped…

Blind Spot Experiment Explo 2

Blind Spot

To see or not to see. The eye’s retina receives and reacts to incoming light and sends signals to the brain, allowing you to see. One part of the retina,…

Cold Metal Main

Cold Metal

"Cold" metal and "warm" wood may be the same temperature. Your hand isn't always a good thermometer. When you touch a variety of materials, some will seem…

Color Contrast Main

Color Contrast

A colored object may look different against different-colored backgrounds. In this investigation, you'll discover how colors seem to change when you place them…

Disappearingact main

Disappearing Act

If you want to stay hidden, you’d better stay still. Some animals blend in with their surroundings so well that they’re nearly impossible to see. Only when…

Groovy Sounds Main

Groovy Sounds

Build a paper-pencil-pin phonograph. In this classic activity, make a record player out of simple materials and listen to your favorite vinyl LP—no outlet…

Head Harp Main

Head Harp

Learn a little string theory. Wrap a string around your head and pluck it to play music.

Hole In Your Hand Main

Hole In Your Hand

What happened to your whole hand? You have two eyes, yet you see only one image of your environment. If your eyes receive conflicting information, what does…

Life Size Main

Life Size

Explore the size and scale of microscopic biology. Not only is it hard to conceptualize things that are too small to see, it’s often surprising to discover the…

Moire Patterns Main

Moire Patterns

Imperfect alignment can lead to interesting patterns. When you look through one chain-link fence at another, you sometimes see a pattern of light and dark…

Seed Germinators Main

Seed Germinator

Watch the life of a plant embryo unfold. What goes on underground when seeds are sprouting? Make yourself a window into the process of plant development.

Sound Bite Main

Sound Bite

Tune in to tunes with your teeth. When you listen to a radio or music player, you normally hear the sound coming from the speaker or headphones. But sound…

Tiny Hot Pile Main

Tiny Hot Pile

Microbial decomposers heat things up. No yard? No problem. Make a mini indoor compost pile, and look for evidence of microbial metabolism.

Your Sense Of Taste Main

Your Sense of Taste

Discover the real taste of candy. Think of some of your favorite tastes: savory Thanksgiving turkey, buttery mashed potatoes, tangy cranberry sauce, and warmly…