The Eye Trix

Scream out what color each of the words are! You'll be shocked at what you say.

Is the picture an old woman or young lady? You decide.

You should be able to see the faces between the vases. Or maybe you see the the vases between the faces.

What's Going On?

     The Rubin vase/profile illusion is an ambiguous figure/ground illusion. This is because it can be perceived either as white faces looking at each other, in front of a black background, or as a black vase on a white background.

     In the case of a figure/ground reversal one line can have two shapes. The shape of the contour formed depends on which side of the line is regarded as part of the figure. This is important, because the visual system represents or encodes objects primarily in terms of their contours.  Also, elements that are close to one another or alike or homogeneous in certain respects tend to be grouped together. This is called grouping. The sudden reversal that you perceive may be due to your shift of attention on the shape of the contour. The observer's "perceptual set" and individual interests can also bias the situation. Biasing the shapes or contours can make one interpretation stronger than the other one. As one can see in the three-dimensional model of the vase, which biases the vase.

     There is no doubt that this particular illusion occurs involves more than just your eyes, but also your memory and higher brain functions. This is because you have stored information in your brain that contains knowledge about vases and the profile of human faces.    

     Your brain needs to be able to interpret the patterns in your eye in terms of external objects. To do this your visual system needs to be able to distinguish objects (figure) from their background (ground). Most of the time this is relatively easy, but sometimes, as in the case of camouflage, it can be made much more difficult.

     The vase/profile illusion is important because it shows that perception is not solely determined by an image formed on the retina. The spontaneous reversal that you observe illustrates the dynamic nature of subtle perceptual processes. These processes underscore how your brain organizes its visual environment.

There are small, dark spots at the intersections of the white lines.   Why is this?

This page was created by J.T. Schemm of Newton North High School

Comments and suggestions can be sent by e-mail to J.T. Schemm

This page last updated on 06/12/07.