Angry and calm faces

If you look at this image, the face on the left looks like an angry old man, while the one on the right looks like a calm woman.

Step back from your computer five or ten feet, and you will see that the images seem to change places!

The thing is that coarse features and fine features are distinguished differently at different distances.When both sets of features are blended into one image, the mind sees the different feature sets, depending on the distance of the viewer.

Here is the original post. There is also some real research done on this.

Thanks to Valera Yundin for the link.