Background

The Necker cube is a classic, perhaps the classic, example of a multistable image. In this case, you can seen the cube in two possible ways: the cube can be going down and to the right or up and to the left. Two different faces can be see and the front face. Look at the image below.

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Use this activity to explore the fun of the Necker cube.

Instructions

Full Screen Mode

To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.

Illustration Tab

Settings

Below is a list of the ways that you can alter the illustration. The settings include the following:

Proportion: adjust the size of the square that is up and to the left. If you make this square smaller, the depth cue of relative size helps it appear farther away. How does that affect your seeing the cube in the two different ways?
Size: adjust the size of the two squares of interest.
Line Thickness: adjust the thickness of the lines making up the cube.
Dashed Lines: select to make the lines dashed.

Reset

Pressing this button restores the settings to their default values.