Multistable images

Multistable images are images that can be viewed in two different ways depending what one is looking for. The first image shows a woman looking into a vanity mirror, but seen differently the woman and mirror assume the shape of a skull. (The image, I think, works better in black-and-white, so you can just desaturate the pix in Paint or another image editor, making it black and white.)

The second iamge here shows a duck read from left to right but a rabbit read from right to left (the duck's beak becomes the rabbit's ears).

The third multstable image shows a vase in white against a black background but two men talkiing in black against a white background.

These multistable images are used in Gestalt psychology tests.