When you woke up this morning and opened your eyes, the world appeared before you without your having to think about it, call it into being or work out the complex physiology of vision. You didn’t have to consciously interpret the wavelengths of light being reflected off your walls to see the colors and shapes in the wallpaper, your brain busily interprets the signals from your eyes to create the world around you. You take for granted that these perceptions are the real world.

But what happens when we consciously switch visual perception? Ambiguous illusions are pictures or objects that elicit a perceptual “switch” between alternative interpretations. Perhaps the most famous ambiguous illusion is Rubin’s Vase.

When something surrounds another thing, the object surrounded becomes the figure and that surrounding it becomes the ground. The brain shapes the incoming information in one recognizable pattern, but with an ambiguous illusion, there are two possible visual interpretations. Note how your visual perception of the inverted vase differs.

What is your intial interpretation of the image below? Do you see a face? If you study the image, does an alternative interpretation appear? Look again. Do you see an eskimo? Now consciously switch your visual perception by thinking about the alternate interpretations as you look at the image.

Often, the alternate interpretation of an image is only realized after prompting or a period of studying the image. Once realized, it is then difficult for the viewer to see anything but the second interpretation.

For humans, “seeing” the world is not just a function of eyesight, it is influenced by the way the brain interprets the data sent to it by the eyes. Take another look at that wallpaper pattern, you may see something you never noticed before.