The Dragon's Gaze

Are you ready to create your own enchanted dragon from a simple sheet of paper? Something strange will happen when you look at it out of one eye and move your head from side to side. The creature will seem to be following you! This illusion was the inspiration for the large and impressive sculpture at the entrance to the Science Museum.

What to do

• Download and print out the drawing of the dragon (a PDF file).
• Cut, fold, and tape or glue it according to the instructions.
• Place the dragon on a table or windowsill.

Now, close one eye, keep looking at the dragon with the other eye, and move your head from side to side. Is the dragon following you?

Note: Be sure to stare at the dragon for several seconds with your open eye, and try consciously to see its face as three-dimensional.

Where's the science here?
When we close one eye, we get false hints from the environment. We get the mistaken impression that the dragon's nose juts out (even though its face is hollow). This illusion demonstrates how much we're affected by past experience. We've learned that faces are three-dimensional and not flat, and that's the interpretation we prefer. Our tendency to see a facial feature as jutting out is stronger than any hint we get about its depth, from shadows for instance.

As we travel through our world, the picture of stationary objects reaching our eyes changes all the time. Yet we know it's not the objects that are moving; it's our perspective that's changing. Our brains build a model of a change that's likely to take place, and when conditions are exactly in line with that model, no illusion is created. When the change does not coincide with our brain's model, we sense that the object is moving. In both the Spinning Head illusion [link] and the Dragon's Gaze illusion, the change that takes place is the opposite of what we expect. Our sense, then, is that the object turns in our direction. The dragon follows us as we turn our heads left and right. If we nod our heads up and down, the dragon's head will appear to be imitating that movement as well.